Display device

Abstract

Provided is a display device having a plurality of light-emitting elements arranged on a substrate, wherein each of the light-emitting elements is provided with: a photonic crystal structure including a light-emitting layer comprising a high-refractive-index layer formed from a compound semiconductor, a periodic structure comprising a plurality of columnar bodies provided in the light-emitting layer, and a resonator formed by a defect that disturbs the periodic structure; and a pair of low-refractive-index layers sandwiching the light-emitting layer from above and below, and the film thickness of the light-emitting layer is 0.4-1.6 times the period length of the periodic structure.

Description

Display device

[0001] The present disclosure relates to a display device.

[0002] In recent years, development of display devices using self-emitting elements such as electroluminescence (EL) elements as light-emitting elements has been progressing. In such a display device, for example, a plurality of light-emitting elements having a stacked structure composed of a lower electrode, a light-emitting layer stacked on the lower electrode, and an upper electrode stacked on the light-emitting layer are arranged on a substrate. Then, when a predetermined voltage is applied to the lower electrode and the upper electrode, the light-emitting layer sandwiched between the lower electrode and the upper electrode emits light.

[0003] Japanese Patent Application Laid-Open No. 2004-289096

[0004] Since the above-described display device can display a high-quality and high-definition image, it can be used not only for direct-view display devices such as monitors but also for small display devices such as electronic viewfinders (EVFs) and head-mounted displays (HMDs). In particular, in order to use the display device for applications such as virtual reality (VR) and augmented reality (AR), it is preferable to further increase the forward emission intensity of light. Therefore, in the light-emitting elements mounted on such a display device, it is required to further increase the utilization efficiency of light emission.

[0005] Therefore, the present disclosure proposes a technique capable of further increasing the utilization efficiency of light emission.

[0006] According to the present disclosure, there is provided a display device having a plurality of light-emitting elements arranged on a substrate, each of the light-emitting elements including a photonic crystal structure including a light-emitting layer made of a high refractive index layer formed from a compound semiconductor, a periodic structure formed by a plurality of columnar bodies provided in the light-emitting layer, and a resonator formed by a defect that disturbs the periodic structure, and a pair of low refractive index layers sandwiching the light-emitting layer from above and below, wherein the film thickness of the light-emitting layer is 0.4 times or more and 1.6 times or less the period length of the periodic structure.

[0007] This is a schematic diagram showing an example of the overall configuration of a display device according to an embodiment of this disclosure. This is a circuit diagram showing an example of a subpixel of a display device according to an embodiment of this disclosure. This is a schematic diagram showing an example of the cross-sectional configuration of a light-emitting element according to the first embodiment of this disclosure. This is a schematic diagram (part 1) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the first embodiment of this disclosure. This is a schematic diagram (part 2) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the first embodiment of this disclosure. This is a schematic diagram (part 1) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the second embodiment of this disclosure. This is a schematic diagram (part 2) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the second embodiment of this disclosure. This is a schematic diagram (part 1) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the third embodiment of this disclosure. This is a schematic diagram (part 2) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the third embodiment of this disclosure. This is a schematic diagram (part 3) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the third embodiment of this disclosure. This is a schematic diagram (part 1) showing an example of the cross-sectional configuration of the main part of a light-emitting element according to the fourth embodiment of this disclosure. This is a schematic diagram (part 2) showing an example of the cross-sectional configuration of the main part of the light-emitting element according to the fourth embodiment of this disclosure. This is a schematic diagram (part 3) showing an example of the cross-sectional configuration of the main part of the light-emitting element according to the fourth embodiment of this disclosure. This is a schematic diagram (part 5) showing an example of the cross-sectional configuration of the main part of the light-emitting element according to the fifth embodiment of this disclosure. This is a schematic diagram (part 1) showing an example of the cross-sectional configuration of the main part of the light-emitting element according to the sixth embodiment of this disclosure. This is a schematic diagram (part 2) showing an example of the cross-sectional configuration of the main part of the light-emitting element according to the seventh embodiment of this disclosure. This is a schematic diagram (part 1) showing the manufacturing process of the light-emitting element according to the first embodiment of this disclosure. This is a schematic diagram (part 2) showing the manufacturing process of the light-emitting element according to the first embodiment of this disclosure. This is an explanatory diagram (part 1) for explaining the embodiment. This is an explanatory diagram (part 2) for explaining the embodiment. This is an explanatory diagram (part 3) for explaining the embodiment. This is an explanatory diagram (part 4) for explaining the embodiment. This is an explanatory diagram (part 5) for explaining the embodiment. This is a conceptual diagram (part 1) for explaining the relationship between the normal LN passing through the center of the light-emitting part, the normal LN' passing through the center of the lens member, and the normal LN'' passing through the center of the wavelength selection part.This is a conceptual diagram (part 2) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN" passing through the center of the wavelength-selecting part. This is a conceptual diagram (part 3) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN" passing through the center of the wavelength-selecting part. This is a conceptual diagram (part 4) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN" passing through the center of the wavelength-selecting part. This is a conceptual diagram (part 5) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN" passing through the center of the wavelength-selecting part. This is a conceptual diagram (6) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN'' passing through the center of the wavelength-selecting part. This is a conceptual diagram (7) illustrating the relationship between the normal vector LN passing through the center of the light-emitting part, the normal vector LN' passing through the center of the lens member, and the normal vector LN'' passing through the center of the wavelength-selecting part. This is a schematic cross-sectional view illustrating the first example of a resonator structure. This is a schematic cross-sectional view illustrating the second example of a resonator structure. This is a schematic cross-sectional view illustrating the third example of a resonator structure. This is a schematic cross-sectional view illustrating the fourth example of a resonator structure. This is a schematic cross-sectional view illustrating the fifth example of a resonator structure. This is a schematic cross-sectional view illustrating the sixth example of a resonator structure. This is a schematic cross-sectional view illustrating the seventh example of a resonator structure. This is a front view showing an example of the appearance of a digital still camera. This is a rear view showing an example of the appearance of a digital still camera. This is an external view of a head-mounted display. This is an external view of a see-through head-mounted display. This is an external view of a television system. This is an external view of a smartphone. This is a diagram (part 1) showing the internal structure of a car. This is a diagram (part 2) showing the internal structure of a car.

[0008] Preferred embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configuration will be denoted by the same reference numeral to avoid redundant explanation. In addition, in this specification and drawings, multiple components having substantially the same or similar functional configurations may be distinguished by adding a different alphabet after the same reference numeral. However, if there is no particular need to distinguish each of multiple components having substantially the same or similar functional configurations, only the same reference numeral will be used.

[0009] Furthermore, the drawings referenced in the following description are intended to illustrate and facilitate understanding of one embodiment of this disclosure, and for the sake of clarity, the shapes, dimensions, ratios, etc. shown in the drawings may differ from those of the actual product. In addition, the apparatus shown in the drawings may be modified in design as appropriate, taking into consideration the following description and known technology.

[0010] Furthermore, in the following descriptions of circuits (electrical connections), unless otherwise specified, "electrically connected" means connecting multiple elements in such a way that electricity (signals) can conduct through them. In addition, "electrically connected" in the following descriptions includes not only cases where multiple elements are directly and electrically connected, but also cases where they are indirectly and electrically connected through other elements.

[0011] The explanation will proceed in the following order: 1. Display device according to the embodiment of the present disclosure 1.1 Display device 1.2 Pixel 2. Background 3. First embodiment 4. Second embodiment 5. Third embodiment 6. Fourth embodiment 7. Fifth embodiment 8. Sixth embodiment 9. Seventh embodiment 10. Manufacturing method 11. Examples 12. Summary 13. Modifications 13.1 Modification 1 13.2 Modification 2 14. Application examples 15. Supplement

[0012] <<1. Display Device According to the Embodiment of the Present Disclosure>> <1.1 Display Device> First, with reference to Figure 1, an example of the overall configuration of a display device 10 according to the embodiment of the present disclosure, which is used as a display device or lighting device, will be described. Figure 1 is a schematic diagram showing an example of the overall configuration of a display device 10 according to the embodiment of the present disclosure.

[0013] The display device 10 is, for example, a device in which light-emitting elements such as LEDs (Light Emitting Diodes) or μLEDs are formed in an array. Such a display device 10 can be applied to, for example, display devices for VR (Virtual Reality), MR (Mixed Reality), or AR (Augmented Reality), electronic viewfinders (EVFs), or small projectors. The display device 10 can also be applied to various lighting devices.

[0014] Furthermore, in the embodiments of this disclosure, the light-emitting element may be a self-emitting element or a current-driven electro-optic element. For example, in addition to LEDs, current-driven electro-optic elements include Micro(μ)-LEDs, semiconductor laser elements, and the like.

[0015] Here, we will explain using the example of an active-matrix EL display device that uses μLEDs as light-emitting elements. Hereafter, "active-matrix EL display device" will simply be referred to as "display device."

[0016] As shown in Figure 1, the display device 10 has a configuration comprising a pixel array section 20 in which a plurality of subpixels 400, including light-emitting elements, are arranged in a matrix-like (two-dimensional) arrangement on a semiconductor substrate (not shown), and a drive circuit section arranged around the pixel array section 20. The drive circuit section includes, for example, a horizontal drive circuit 11 and a vertical drive circuit 12 mounted on the same display panel 40 as the pixel array section 20, and drives each subpixel 400 of the pixel array section 20.

[0017] Here, if the display device 10 is color-compatible, one pixel (unit pixel) that forms a color image is composed of multiple subpixels 400. More specifically, in a color-compatible display device 10, one pixel may be composed of three subpixels 400, for example, a subpixel 400R that emits red light, a subpixel 400G that emits green light, and a subpixel 400B that emits blue light. Furthermore, a pixel may be composed of, for example, one, two, or more subpixels 400, and is not particularly limited. Also, one pixel is not limited to a combination of three primary color subpixels 400, such as red, green, and blue, but may also be composed of three primary color subpixels 400 with one or more additional subpixels 400 of different colors added to form one pixel. More specifically, the display device 10 may, for example, add a sub-pixel 400 that emits white light to improve brightness, or add at least one sub-pixel 400 that emits complementary light to expand the color reproduction range, thereby forming a single pixel.

[0018] Furthermore, in this embodiment, a single pixel is not limited to being composed of multiple subpixels 400 that emit different light, as described above, but may be composed of multiple subpixels 400 that emit light of the same color. Here, a pixel means the smallest unit (pixel) that is controlled when controlling the light emission of the display device 10, and is composed of multiple subpixels 400 that are treated as a single unit during control. In other words, in this embodiment, the display device 10 has multiple pixels arranged in a matrix on the display panel 40.

[0019] In detail, the horizontal drive circuit 11 scans each sub-pixel 400 row by row (in Figure 1, the direction extending along the X direction is called the row direction) when writing a signal to each sub-pixel 400, and can sequentially supply a scan signal to each scan line SCLm. The horizontal drive circuit 11 can be configured, for example, by a shift register that sequentially shifts (transfers) start pulses in synchronization with the input clock pulse.

[0020] Furthermore, the vertical drive circuit 12 can supply a signal voltage corresponding to the brightness information supplied from a signal source (not shown) to selected sub-pixels 400 in column units (in Figure 1, the direction extending along the Y direction is called the column direction) via the signal line DTLn.

[0021] In the embodiments of this disclosure, the configuration of the display device 10 is not limited to the configuration shown in Figure 1. That is, the configuration shown in Figure 1 is merely an example, and the display device 10 according to the embodiments of this disclosure can take various configurations.

[0022] <1.2 Pixels> Next, the circuit configuration of the sub-pixel 400 of the display device 10 according to the embodiment of the present disclosure shown in Figure 1 will be described. Figure 2 is a circuit diagram showing an example of the sub-pixel 400 of the display device 10 according to the embodiment of the present disclosure, and more specifically, it is a schematic circuit diagram for explaining the wiring relationship in the sub-pixel 400 of the mth row and nth column.

[0023] In the display device 10, as previously described, the subpixels 400 including the light-emitting element 100 have scan lines SCLs that extend in the row direction (X direction in Figure 1). ｍ and the signal line DTL extending in the column direction (Y direction in Figure 1) ｎ They are arranged in a two-dimensional matrix while connected to each other.

[0024] Furthermore, as shown in Figure 2, the display device 10 has a power supply line PS1 that supplies a drive voltage to the subpixels 400. ｍ It also has a common power supply line PS2 that is connected to all sub-pixels 400 in common. And power supply line PS1 ｍ A predetermined drive voltage VCC etc. is supplied from the power supply unit (not shown), and a common voltage V is supplied to the common power supply line PS2. Ｃａｔ (For example, ground potential) is supplied.

[0025] Here, let M be the number of scan lines SCL and power lines PS1. Subpixel 400 of the mth row (where m = 1, 2..., P) is the mth scan line SCL ｍ , the mth power supply line PS1 ｍ It is connected to and constitutes one row of display elements. Note that in Figure 2, the scan line SCL ｍand the power supply line PS1 ｍ Only is shown. Also, let the number of signal lines DTL be N. The sub-pixel 400 in the n-th column (where n = 1, 2,..., N) is connected to the n-th signal line DTL ｎ In FIG. 2, only the signal line DTL ｎ is shown. Hereinafter, the sub-pixel 400 located at the m-th row and n-th column may be referred to as the (n, m)-th sub-pixel 400

[0026] And, as described above, the display device 10 is sequentially scanned row by row by the scanning signal from the horizontal drive circuit 11. Specifically, in the display device 10, M sub-pixels 400 arranged in the m-th row are simultaneously driven. In other words, in the M sub-pixels 400 arranged along the row direction, the timing of their light emission / non-light emission is controlled in units of the rows to which they belong. For example, when the display frame rate of the display device 10 is FR (times / second), the scanning period per row (so-called horizontal scanning period) when the display device 10 is sequentially scanned row by row is less than (1 / FR)×(1 / P) seconds

[0027] Also, as shown in FIG. 2, the sub-pixel 400 is composed of a light-emitting element 100 and a drive circuit for driving this. The light-emitting element 100 is an inorganic electroluminescence light-emitting element. The drive circuit is composed of a writing transistor TR Ｗ , and a drive transistor TR Ｄ , and a capacitance portion C １ . When current flows through the drive transistor TR Ｄ to the light-emitting element 100, the light-emitting element 100 can emit light. Each transistor is composed of, for example, a p-channel type field effect transistor

[0028] As shown in FIG. 2, in the sub-pixel 400, one source / drain region of the drive transistor TR Ｄ is electrically connected to one end of the capacitance portion C １ and the power supply line PS1 ｍ , and the other source / drain region is electrically connected to one end (specifically, the anode electrode) of the light-emitting element 100. The drive transistor TRＤ The gate electrode is the writing transistor TR Ｗ It is connected to the other source / drain region, and the capacitance section C １ It is electrically connected to the other end.

[0029] Also, as shown in Figure 2, the writing transistor TR Ｗ One of the source / drain regions is the signal line DTL ｎ It is electrically connected to the writing transistor TR Ｗ The gate electrode is the scan line SCL ｍ It is electrically connected to it.

[0030] Furthermore, as shown in Figure 2, the other end of the light-emitting element 100 (specifically, the cathode electrode) is electrically connected to the common power supply line PS2. In addition, a predetermined cathode voltage V is supplied to the common power supply line PS2. Ｃａｔ This is supplied. In Figure 2, the capacitance of the light-emitting element 100 is indicated by the code C. ＥＬ It is represented as follows.

[0031] The overview of the driving of the sub-pixel 400 will be described. In the sub-pixel 400, the signal line DTL is transmitted from the vertical drive circuit 12. ｎ With a voltage corresponding to the brightness of the image to be displayed supplied, the writing transistor TR is activated by a scanning signal from the horizontal drive circuit 11. Ｗ When it is in a conductive state, capacitance part C １ A voltage corresponding to the brightness is written to it. (Writing transistor TR) Ｗ After the capacitor is de-conducted, the capacitance part C １ The drive transistor TR operates according to the voltage held in Ｄ When an electric current flows through it, the light-emitting element 100 emits light.

[0032] In the embodiments of this disclosure, the configuration of the drive circuit that controls the light emission of the light-emitting element 100 is not limited to the configuration shown in Figure 2. Therefore, the configuration shown in Figure 2 is merely an example, and various configurations can be taken in the display device 10 according to the embodiments of this disclosure.

[0033] <<2. Background>> Next, before describing the details of the embodiments of this disclosure, the background to the inventors' creation of the embodiments of this disclosure will be explained.

[0034] As explained earlier, the light-emitting element 100 is required to have a higher efficiency in utilizing light emission. Therefore, in conventional light-emitting elements, the structure of the light-emitting element is optimized so that the efficiency of light extraction is improved for each color of light emitted from the light-emitting layer of the light-emitting element. Specifically, in conventional light-emitting elements, since the light emitted from the light-emitting layer is emitted in all directions, a reflector or the like is used to control the light so that it travels upwards towards the light-emitting element. However, since most of the light emitted from the light-emitting layer does not travel upwards towards the light-emitting element, conventional light-emitting elements could not be said to have high light emission utilization efficiency.

[0035] Therefore, the inventors devised a method of providing a photonic crystal structure within the light-emitting layer. A photonic crystal structure is an artificial crystal with a nanoperiodic structure in which materials with different refractive indices are arranged periodically at intervals approximately the same as the wavelength of light. Due to the band gap effect of this periodic structure, light of a predetermined wavelength can be confined within it. In other words, the inventors considered that by providing a photonic crystal structure within the light-emitting layer, they could confine and resonate light within the photonic crystal structure in the planar direction of the photonic crystal structure, thereby increasing the intensity of the light (brightness, color purity).

[0036] However, it was found that using the photonic crystal structure described above does not allow for the Purcell effect to be obtained, and there are limitations to efficiently increasing the intensity of light (brightness, color purity). Therefore, the inventors devised a method to introduce disordered periodic structures (tiny defects) into the photonic crystal structure. Light with wavelengths corresponding to the periodic structure of the photonic crystal structure is confined and resonates in the defects and the regions surrounding the defects, so the defects and the regions surrounding the defects function as optical resonators. Furthermore, by reducing the mode volume (V) of the resonator due to the defects and increasing the Q value of the resonator, the speed and intensity of light emission can be increased by the Purcell effect. In detail, since the photon density in the optical resonator is proportional to Q / V, by reducing the mode volume of the resonator and increasing the Q value, light can be confined in a small region at an extremely high density for a long time. As a result, the speed and intensity of light emission can be increased by the Purcell effect. Therefore, the inventors conceived the idea of ​​using a photonic crystal structure with introduced defects to further increase the brightness and color purity of light.

[0037] In the planar direction of the photonic crystal structure, light of a predetermined wavelength is confined to the defects and the regions surrounding the defects due to the bandgap effect caused by the periodic structure. On the other hand, in the film thickness direction of the photonic crystal structure (emissive layer), by sandwiching the emissive layer made of a high refractive index material between low refractive index layers, the light is confined within the photonic crystal structure (emissive layer) due to the reflection effect at the interface between the emissive layer and the low refractive index layer.

[0038] However, when a light-emitting layer made of compound semiconductor material is used, the refractive index difference between the light-emitting layer and the low refractive index layer is small, making it difficult to obtain a total internal reflection effect or reflection effect at these interfaces. Therefore, in the film thickness direction of the photonic crystal structure (light-emitting layer), it is difficult to suitably confine a large amount of light within the photonic crystal structure (light-emitting layer), and there were limitations in efficiently making the resonator due to the defect 128 function.

[0039] Therefore, in light of these circumstances, the inventors have diligently studied the structure of the light-emitting element 100 and have come up with the embodiments of the present disclosure described below. According to the embodiments of the present disclosure, it is possible to more efficiently increase the intensity of light (luminance, color purity) and to more easily control the direction of light propagation in the direction of the film thickness of the light-emitting layer (control of the radiation angle). In other words, according to these embodiments, the utilization efficiency of light emission in the light-emitting element 100 can be further increased. The details of the embodiments of the present disclosure created by the inventors will be described in order below.

[0040] <<3. First Embodiment>> First, the detailed configuration of the light-emitting element 100 according to the first embodiment of the present disclosure will be described with reference to Figures 3, 4A, and 4B. Figure 3 is a schematic diagram showing an example of the cross-sectional configuration of the light-emitting element 100 according to the present embodiment. Figure 4A is a schematic diagram showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to the present embodiment, and in detail is an enlarged view of the area enclosed by the dashed line in Figure 3. Figure 4B is a schematic diagram showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to the present embodiment, and in detail is a cross-sectional view obtained by cutting the light-emitting element 100 along the line B-B' in Figure 3.

[0041] In the display device 10 according to this embodiment, a plurality of light-emitting elements 100 that emit light upward are arranged in a matrix in a predetermined area on the substrate 150 (see Figure 3). Each of the light-emitting elements 100 can be, for example, a light-emitting element 100 that emits red light, a light-emitting element 100 that emits green light, or a light-emitting element 100 that emits blue light.

[0042] As shown in Figure 3, the light-emitting element 100 according to this embodiment has a laminated structure in which a reflector (reflective layer) 140, a low refractive index layer 130, a lower electrode (first transparent conductive layer) 110, a light-emitting layer 102, an upper electrode (second transparent conductive layer) 112, a low refractive index layer 132, and an on-chip lens 152 are sequentially stacked on a substrate 150 in this order. Furthermore, in this embodiment, a photonic crystal structure 104 is provided within the light-emitting layer 102. The details of each element of the light-emitting element 100 according to this embodiment will be described sequentially below.

[0043] (Substrate 150) The substrate 150 can be formed from a transparent material such as glass or a semiconductor material such as silicon. For example, the drive circuit for driving the light-emitting element 100 may be constructed by appropriately forming transistors, wiring, etc., within the various substrates 150 described above.

[0044] (Reflector 140) The reflector 140 can reflect the light emitted from the light-emitting layer 102 upward toward the light-emitting element 100. The reflector 140 can be made of, for example, aluminum (Al), silver (Ag), copper (Cu), or an alloy thereof. In this embodiment, the reflector 140 can be provided below the light-emitting layer 102, which will be described later, for example, on the side of the low refractive index layer 130 opposite to the light-emitting layer 102.

[0045] (Low refractive index layer 130) The low refractive index layer 130 is made of a low refractive index material having a refractive index of 2 or less, and by sandwiching the light-emitting layer 102, which is made of a high refractive index material, together with the low refractive index layer 132 described later, light can be confined in the light-emitting layer 102. The low refractive index layer 130 is made of, for example, silicon nitride (SiN ｘ ), silicon oxide (SiO ｘ ), silicon oxynitride (SiO ｘ N ｙ It can be formed from inorganic insulating materials such as ), or organic resin materials such as acrylic resins or polyimide resins. The low refractive index layer 130 may also be a single layer or a laminate of the above-mentioned material.

[0046] (Lower electrode 110) In this embodiment, the lower electrode 110 may be formed from a transparent conductive material that has good light transmittance to visible light (for example, visible light with a wavelength of about 360 nm to 780 nm). For example, the lower electrode 110 can be formed from a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO). Alternatively, the lower electrode 110 can be formed from a metal film containing at least one of the elements and alloys of metals such as aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), and silver (Ag). Specific examples of alloys include aluminum (Al) alloys such as MgAg alloy or AlLi alloy, and silver (Ag) alloys.

[0047] (Light-emitting layer 102) The light-emitting layer 102 is a layer that emits light and is made of a high refractive index material (high refractive index layer) formed from a compound semiconductor having a refractive index greater than 2. More specifically, in this embodiment, as shown in Figure 4A, the light-emitting layer 102 has a laminated light-emitting structure consisting of, for example, a compound semiconductor layer (first compound semiconductor layer) 122, an active layer 120, and a compound semiconductor layer (second compound semiconductor layer) 124. The laminated light-emitting structure in which the compound semiconductor layer 122, the active layer 120, and the compound semiconductor layer 124 are laminated can be made of, for example, a GaN-based compound semiconductor (including AlGaN mixed crystal, AlInGaN mixed crystal, or GaInN mixed crystal), an AlGaInAs-based compound semiconductor, an AlGaInP-based compound semiconductor, a ZnSe-based compound semiconductor (for example, including ZnS, ZnSSe, and ZnMgSSe), or a ZnO-based compound semiconductor. More specifically, AlInGaN-based compound semiconductors include GaN, AlGaN, InGaN, and AlInGaN. Furthermore, these compound semiconductors may optionally contain boron (B) atoms, thallium (Tl) atoms, arsenic (As) atoms, phosphorus (P) atoms, antimony (Sb) atoms, and the like.

[0048] The active layer 120 preferably has a quantum well structure. Specifically, the active layer 120 may have a single quantum well structure (SQW structure) or a multiple quantum well structure (MQW structure). More specifically, the single quantum well structure has a structure in which a semiconductor layer with a thickness of several tens of nanometers or less is sandwiched on both sides by layers with a larger band gap than the semiconductor layer. Since the potential of the layer with the smaller band gap is lower than that of the layer with the larger band gap, a potential well (quantum well) is created. Furthermore, stacking several to tens of such quantum well structures results in a multiple quantum well structure.

[0049] The active layer 120 having a quantum well structure has a structure in which at least one well layer and a barrier layer are stacked, and the combination of (compound semiconductor constituting the well layer, compound semiconductor constituting the barrier layer) is, for example, (In ｙ Ga （１－ｙ） N, GaN), (In ｙ Ga （１－ｙ） N, In ｚ Ga （１－ｚ） N) [However, y > z], (In ｙ Ga （１－ｙ） Examples include N, AlGaN, etc. Furthermore, the compound semiconductor layer 122 may be composed of a compound semiconductor of a first conductivity type (e.g., n-type), and the compound semiconductor layer 124 may be composed of a compound semiconductor of a second conductivity type (e.g., p-type) different from the first conductivity type. Moreover, the compound semiconductor layers 122 and 124 may be single-structure layers, multilayer layers, or superlattice layers. In addition, the compound semiconductor layers 122 and 124 may be composition-graded layers or concentration-graded layers.

[0050] Furthermore, the quantum well structure may be, for example, a one-dimensional quantum well structure (quantum wire), a zero-dimensional quantum well structure (quantum dot), or the like.

[0051] (Upper electrode 112) In this embodiment, the upper electrode 112 may be formed from a transparent conductive material that has good light transmittance to visible light, for example. For example, the upper electrode 112 can be formed from a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO). Alternatively, the upper electrode 112 can be formed from a metal film containing at least one of the elements and alloys of metals such as aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), and silver (Ag). Specific examples of alloys include aluminum (Al) alloys such as MgAg alloy or AlLi alloy, and silver (Ag) alloys.

[0052] (Low refractive index layer 132) The low refractive index layer 132 is made of a low refractive index material having a refractive index of 2 or less, and as explained above, by sandwiching the light-emitting layer 102, which is made of a high refractive index material, together with the low refractive index layer 130, light can be confined in the light-emitting layer 102. The low refractive index layer 132 is made of, for example, silicon nitride (SiN ｘ ), silicon oxide (SiO ｘ ), silicon oxynitride (SiO ｘ N ｙ It can be formed from inorganic insulating materials such as ), or organic resin materials such as acrylic resins or polyimide resins. The low refractive index layer 132 may also be a single layer or a laminate of the above-mentioned material.

[0053] (On-chip lens 152) The on-chip lens 152 can be formed from, for example, a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin. The on-chip lens 152 can emit light as collimated light towards the upper front of the light-emitting element 100 or diagonally upward of the light-emitting element 100, that is, in a desired direction.

[0054] In this embodiment, the lens structure is not limited to the on-chip lens 152, and a lens structure capable of guiding light in a desired direction may be used. Examples of such lens structures include metasurfaces and waveguides. Here, a metasurface refers to a structure in which structures smaller than the wavelength of light are periodically arranged in two dimensions, and can be formed from, for example, metal or dielectric material. Furthermore, when using a metasurface, the metasurface is not limited to being provided for each light-emitting element 100 (sub-pixel 400), but may be provided so as to span multiple light-emitting elements 100.

[0055] (Photonic crystal structure 104) As explained above, the photonic crystal structure 104 is an artificial crystal with a nanoperiodic structure in which materials with different refractive indices are arranged periodically at intervals approximately the same as the wavelength of light. Due to the band gap effect of this periodic structure, light of a predetermined wavelength can be confined inside. Furthermore, by introducing local periodic disturbances (in this specification, the locations of periodic disturbances are also referred to as "defects") into the photonic crystal structure 104, light in the band gap range due to the periodic structure is confined in the region around the defect, and this region can function as an optical resonator.

[0056] In detail, in this embodiment, as shown in Figure 4A, a photonic crystal structure 104 is provided within the light-emitting layer 102. The photonic crystal structure 104 consists of a plurality of columnar bodies 126 having nanoscale diameters arranged periodically. Furthermore, each columnar body 126 penetrates the entire light-emitting layer 102 along the thickness of the light-emitting layer 102. The columnar bodies 126 can be made of a material with a different refractive index from the surrounding material, or they can be voids. For example, hydrogen silsesquioxane (HSQ) can be used as a material with a different refractive index from the surrounding material. In this embodiment, it is preferable that the columnar bodies 126 are formed from a material with a different refractive index from the surrounding material, as this makes deformation of the photonic crystal structure 104 less likely to occur compared to when they are voids, and reduces variations in the various characteristics of the optical resonator.

[0057] Furthermore, in this embodiment, as shown in Figure 4B, the multiple columnar bodies 126 are regularly arranged in a point-symmetric manner with respect to the center of the photonic crystal structure 104. In the following description, as shown in Figure 4B, the period length of the columnar bodies 126 (the distance between the centers of two adjacent columnar bodies 126) will be denoted as a.

[0058] Furthermore, in this embodiment, as shown in Figures 4A and 4B, a minute defect 128 is introduced in the center of the photonic crystal structure 104 where the periodic arrangement of columnar bodies 126 is disrupted, that is, where columnar bodies 126 are absent. In this embodiment, light having a wavelength corresponding to the periodic structure of the photonic crystal structure 104 is confined and resonates in the defect 128 and the surrounding region of the defect 128. Specifically, in the planar direction of the photonic crystal structure 104 (the plane parallel to the surface of the substrate 150), the light is confined to the region of the defect 128 due to the bandgap effect caused by the periodic structure. Furthermore, in this embodiment, in the film thickness direction of the photonic crystal structure 104 (light-emitting layer 102), the light is confined to the photonic crystal structure 104 (light-emitting layer 102) due to the reflection effect at the interface between the light-emitting layer 102 and the low refractive index layer 130, and at the interface between the light-emitting layer 102 and the low refractive index layer 132. In this embodiment, a resonance mode localized in the region of defect 128 is generated. Therefore, in this embodiment, the region around defect 128 functions as an optical resonator, and the intensity of light (brightness, color purity) can be efficiently increased.

[0059] In this embodiment, the photonic crystal structure 104 is not limited to being a photonic crystal structure 104 having the defects described above. In this embodiment, for example, the photonic crystal structure 104 may include periodic structural disorder by changing the size, spacing, and shape of some of the unit structures within the photonic crystal structure 104. Furthermore, in this embodiment, the periodic structural disorder (defect 128) is not limited to being located in the center of the photonic crystal structure 104. Also, in this embodiment, the photonic crystal structure 104 may include multiple periodic structural disorderes.

[0060] Furthermore, in this embodiment, since the volume of the defect 128 and the surrounding region of the defect 128 are extremely small, the mode volume (V) of the resonator due to the defect 128 is very small. Therefore, according to this embodiment, by using a resonator due to the defect 128, the intensity of light (luminance, color purity) can be efficiently increased by the Purcell effect. In detail, since the photon density in the optical resonator is proportional to Q / V (where Q is the Q value of the resonator), by making the mode volume small and the Q value high, light can be confined in a small region at an extremely high density for a long time. Therefore, with such an optical resonator, the speed and intensity of light emission can be increased by the Purcell effect.

[0061] In addition, in this embodiment, much of the light emitted from the light-emitting layer 102 is extracted from minute defects 128 and the surrounding regions of the defects 128 in the photonic crystal structure 104, in the direction of the film thickness of the photonic crystal structure 104 (light-emitting layer 102). Therefore, in this embodiment, it becomes easy to control the direction of light propagation in the direction of the film thickness of the light-emitting layer 102 (control of the radiation angle).

[0062] However, as explained above, in the light-emitting devices that the inventors had been studying until now, the refractive index difference between the light-emitting layer 102 and the low refractive index layers 130 and 132 was small, making it difficult to obtain total internal reflection and reflection effects at these interfaces. Therefore, in the above light-emitting devices, it was difficult to suitably confine a large amount of light within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102, and there were limitations in efficiently making the resonator due to the defect 128 function.

[0063] Therefore, in this embodiment, based on the simulation results by the inventors (details will be described later), the film thickness t of the light-emitting layer 102 on which the photonic crystal structure 104 is provided (see Figure 4A) is set to 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. In this way, according to this embodiment, light can be suitably confined in the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102. As a result, according to this embodiment, more light can be confined in the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102, so that the resonator due to the defect 128 can function efficiently. As a result, according to this embodiment, the intensity of light (brightness, color purity) can be increased more efficiently, and it becomes easier to control the direction in which light propagates in the direction of the film thickness of the light-emitting layer 102 (control of the radiation angle).

[0064] As described above, in this embodiment, a photonic crystal structure 104 with defects 128 introduced is provided in the light-emitting layer 102. Furthermore, in this embodiment, the film thickness t of the high refractive index light-emitting layer 102 sandwiched between the low refractive index layers 130 and 132 is set to 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, more light can be confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102, thereby enabling the resonator formed by the defects 128 to function efficiently. As a result, according to this embodiment, the intensity of light (brightness, color purity) can be increased more efficiently, and the direction of light propagation can be controlled in the direction of the film thickness of the light-emitting layer 102 (control of the radiation angle) more easily. In other words, according to this embodiment, the utilization efficiency of light emission in the light-emitting element 100 can be increased.

[0065] In this embodiment, the light-emitting element 100 is not limited to the form shown in Figures 3, 4A, and 4B, but can take on various forms.

[0066] <<4. Second Embodiment>> Next, the detailed configuration of the light-emitting element 100 according to the second embodiment of the present disclosure will be described with reference to Figures 5A and 5B. Figures 5A and 5B are schematic diagrams showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail correspond to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0067] In this embodiment, as shown in Figure 5A, unlike the first embodiment described above, the lower electrode 110 may not be provided. Compared with transparent conductive materials (e.g., ITO), silicon oxide (SiO ｘ ) etc. can achieve a high etching selectivity ratio for compound semiconductor materials. Therefore, in this embodiment, instead of the lower electrode 110 being made of a transparent conductive material (for example, ITO, etc.), silicon oxide (SiO ｘ A light-emitting layer 102 made of a compound semiconductor material is provided so as to be in contact with a low refractive index layer 130 made of ) etc. In this embodiment, the difficulty of processing the trench 170 for the columnar body 126 (see Figure 11B) can be reduced. The transparent conductive material is silicon oxide (SiO ｘ It has a higher refractive index compared to other materials, and a lower refractive index compared to compound semiconductor materials. Therefore, in this embodiment, by providing only the upper electrode 112 made of a transparent conductive material, much of the light from the light-emitting layer 102 can be extracted to the upper part of the light-emitting layer 102.

[0068] Furthermore, compound semiconductor layers with a p-type conductivity tend to have higher resistance than compound semiconductor layers with an n-type conductivity. Therefore, in this embodiment, the resistance can be reduced by providing an upper electrode 112 on the compound semiconductor layer 124 side with a p-type conductivity.

[0069] In this embodiment, the configuration is not limited to the configuration shown in Figure 5A, and as shown in Figure 5B, the upper electrode 112 may not be provided. In other words, in this embodiment, only the lower electrode 110 made of a transparent conductive material may be provided.

[0070] In this embodiment as well, the film thickness of the light-emitting layer 102, which is provided with the photonic crystal structure 104, is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102. In this embodiment, it is preferable to increase the film thickness of the compound semiconductor layers 122 and 124 within the above range to lower their resistance.

[0071] In this embodiment, the light-emitting element 100 is not limited to the form shown in Figures 5A and 5B, but can take on various forms.

[0072] <<5. Third Embodiment>> Next, the detailed configuration of the light-emitting element 100 according to the third embodiment of the present disclosure will be described with reference to Figures 6A, 6B, and 6C. Figures 6A, 6B, and 6C are schematic diagrams showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail correspond to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0073] In this embodiment, unlike the first embodiment described above, the lower electrode 110 and the upper electrode 112 may have a structure such that they do not overlap with the region of the resonator caused by the defect 128, as shown in Figure 6A. Specifically, for example, the lower electrode 110 and the upper electrode 112 may have openings 110a and 112a, respectively, at the locations that overlap with the region of the resonator caused by the defect 128. In this embodiment, this makes it easier to extract light from the region of the resonator caused by the defect 128 in the direction of the film thickness of the light-emitting layer 102.

[0074] Furthermore, in this embodiment, as shown in Figure 6B, unlike the embodiment in Figure 6A described above, the lower electrode 110 may have a structure such that it does not overlap with the region of the resonator caused by the defect 128. Specifically, for example, the lower electrode 110 may have an opening 110a at the location where it overlaps with the region of the resonator caused by the defect 128. In this embodiment, this makes it easier to extract light from the region of the resonator caused by the defect 128 in the direction of the film thickness of the light-emitting layer 102. Note that this embodiment is not limited to the form shown in Figure 6B, and for example, the upper electrode 112 may have a structure such that it does not overlap with the region of the resonator caused by the defect 128.

[0075] Furthermore, in this embodiment, as shown in Figure 6C, unlike the first embodiment described above, the lower electrode 110 has a structure that does not overlap with the region of the resonator caused by the defect 128, and the upper electrode 112 has a recess 112b in the area that overlaps with the region of the resonator. In detail, the film thickness of the recess 112b is thinner than the film thickness of the area of ​​the upper electrode 112 that does not overlap with the region of the resonator. In this embodiment, this makes it easier to extract light from the region of the resonator caused by the defect 128 in the direction of the film thickness of the light-emitting layer 102. Note that this embodiment is not limited to the form shown in Figure 6C, and for example, the lower electrode 110 may have a recess in the area that overlaps with the region of the resonator, and the upper electrode 112 may have a structure that does not overlap with the region of the resonator caused by the defect 128.

[0076] In this embodiment as well, the film thickness of the light-emitting layer 102, which is provided with the photonic crystal structure 104, is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102.

[0077] In this embodiment, the light-emitting element 100 is not limited to the form shown in Figures 6A, 6B, and 6C, but can take on various forms.

[0078] <<6. Fourth Embodiment>> Next, the detailed configuration of the light-emitting element 100 according to the fourth embodiment of the present disclosure will be described with reference to Figures 7A, 7B, and 7C. Figures 7A, 7B, and 7C are schematic diagrams showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail correspond to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0079] In this embodiment, unlike the first embodiment described above, as shown in Figure 7A, the multiple columnar bodies 126 may penetrate not only the light-emitting layer 102 but also the lower electrode 110 and the upper electrode 112 along the direction of their film thickness. In this embodiment, this allows for better light confinement and reduces the mode volume (V) of the resonator due to the defect 128. As a result, according to this embodiment, the intensity of light from the resonator can be increased due to the Parcell effect described above.

[0080] Normally, in a minute light-emitting element 100, the area of ​​the light-emitting layer 102 is small, which reduces the brightness of the light-emitting element 100. However, in this embodiment, by using a resonator with a very small mode volume (V), the intensity of light can be increased by the Purcell effect, thus suppressing the reduction in brightness even in a minute light-emitting element 100.

[0081] Furthermore, compared to the embodiment shown in Figure 5B above, in which the upper electrode 112 is not provided, in this embodiment, as shown in Figure 7B, the multiple columnar bodies 126 may penetrate not only the light-emitting layer 102 but also the lower electrode 110 along the film thickness direction. In this embodiment, this allows for better light confinement and reduces the mode volume (V) of the resonator due to the defect 128. As a result, according to this embodiment, the intensity of light from the resonator can be increased due to the Parcell effect described above.

[0082] Furthermore, this embodiment is not limited to the embodiment shown in Figure 7A, and as shown in Figure 7C, the multiple columnar bodies 126 may penetrate the light-emitting layer 102 and the lower electrode 110. In this embodiment, this allows for better light confinement and reduces the mode volume (V) of the resonator due to the defects 128. As a result, according to this embodiment, the intensity of light from the resonator can be increased due to the Parcell effect described above. Note that in the embodiment shown in Figure 7C, the mode volume of the resonator is larger compared to the embodiment shown in Figure 7A. However, in the embodiment shown in Figure 7C, since the columnar bodies 126 do not penetrate the upper electrode 112, the aspect ratio of the trench 170 for the columnar bodies 126 (see Figure 11B) is increased, and the difficulty of processing the trench 170 can be reduced.

[0083] Furthermore, this embodiment is not limited to the embodiment shown in Figure 7C; for example, the multiple columnar bodies 126 may penetrate the light-emitting layer 102 and the upper electrode 112.

[0084] In this embodiment as well, the film thickness of the light-emitting layer 102, which is provided with the photonic crystal structure 104, is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102.

[0085] In this embodiment, the light-emitting element 100 is not limited to the form shown in Figures 7A, 7B, and 7C, but can take on various forms.

[0086] <<7. Fifth Embodiment>> Next, with reference to Figure 8, the detailed configuration of the light-emitting element 100 according to the fifth embodiment of the present disclosure will be described. Figure 8 is a schematic diagram showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail corresponds to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0087] In this embodiment, unlike the first embodiment described above, as shown in Figure 8, insulating layers 160 and 162 may be provided between the light-emitting layer 102 and the lower electrode 110, and between the light-emitting layer 102 and the upper electrode 112, respectively. The insulating layers 160 and 162 may be, for example, silicon nitride (SiN ｘ ), silicon oxide (SiO ｘ ), silicon oxynitride (SiO ｘ N ｙ It can be formed from an inorganic insulating material such as ). Furthermore, in this embodiment, the insulating layers 160 and 162 have a structure that does not overlap with the region of the resonator due to the defect 128. Specifically, for example, the insulating layers 160 and 162 have openings in the areas that overlap with the region of the resonator due to the defect 128.

[0088] In this embodiment, if the thickness of the compound semiconductor layers 122 and 124 is thin and their resistance is high, by providing insulating layers 160 and 162, a voltage (or current) is applied by the lower electrode 110 and the upper electrode 112 only to the region of the resonator caused by the defect 128. Therefore, in this embodiment, only the light-emitting layer 102 located in the region of the resonator caused by the defect 128 can be made to emit light. As a result, according to this embodiment, only the resonator and the vicinity of the resonator emit light, and the resonator causes the light to resonate, so that light can be efficiently emitted from the light-emitting element 100.

[0089] In this embodiment as well, the film thickness of the light-emitting layer 102 is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102.

[0090] Furthermore, in this embodiment, the light-emitting element 100 is not limited to the form shown in Figure 8, but can take on various forms. For example, in this embodiment, only one of the insulating layers 160 and 162 may be provided.

[0091] <<8. Sixth Embodiment>> Next, with reference to Figure 9, the detailed configuration of the light-emitting element 100 according to the sixth embodiment of the present disclosure will be described. Figure 9 is a schematic diagram showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail corresponds to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0092] In this embodiment, unlike the first embodiment described above, as shown in Figure 9, the plurality of columnar bodies 126 may penetrate only a portion of the light-emitting layer 102, rather than the entire thickness of the light-emitting layer 102. Also in this embodiment, the thickness of the light-emitting layer 102 is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar bodies 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the thickness of the light-emitting layer 102.

[0093] In this embodiment, the light-emitting element 100 is not limited to the form shown in Figure 9, but can take on various forms.

[0094] <<9. Seventh Embodiment>> Next, with reference to Figure 10, the detailed configuration of the light-emitting element 100 according to the seventh embodiment of the present disclosure will be described. Figure 10 is a schematic diagram showing an example of the cross-sectional configuration of the main part of the light-emitting element 100 according to this embodiment, and in detail corresponds to an enlarged view of the area enclosed by the dashed line in Figure 3.

[0095] Compared to the embodiment in which the lower electrode 110 shown in Figure 5A above is not provided (second embodiment), in this embodiment, as shown in Figure 10, the low refractive index layer 130 may be composed of a laminate with a low refractive index layer 134 made of a different material. In this embodiment, for example, the low refractive index layer 130 may be made of silicon oxide (SiO ｘ ) is formed with, and a low refractive index layer 134 close to the light-emitting layer 102 is made of silicon nitride (SiN ｘ) is formed from this. In this embodiment, the low refractive index layer 134 can be used as an etching stopper when processing the trench 170 (see Figure 11B) for the columnar body 126. As a result, according to this embodiment, by using the etching stopper, it becomes easy to accurately shape the columnar body 126 into the desired shape and length.

[0096] In this embodiment as well, the film thickness of the light-emitting layer 102 is set to be 1.4 times or more and 1.6 times or less the period length a of the columnar body 126. By doing so, according to this embodiment, light can be suitably confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102.

[0097] Furthermore, in this embodiment, the light-emitting element 100 is not limited to the form shown in Figure 10, but can take on various forms.

[0098] <<10. Manufacturing Method>> Next, an example of a manufacturing method for the light-emitting element 100 according to the first embodiment described above will be explained with reference to Figures 11A and 11B. Figures 11A and 11B are schematic diagrams showing the manufacturing process of the light-emitting element 100 according to the first embodiment of this disclosure.

[0099] First, as shown in the upper part of Figure 11A, for example, an active layer 120 having an MQW structure and a compound semiconductor layer 122 made of n-type GaN are sequentially stacked on a compound semiconductor layer 124 made of p-type GaN. Next, as shown in the second row from the top of Figure 11A, for example, a lower electrode 110 made of ITO is stacked on the compound semiconductor layer 122. Then, as shown in the third row from the top of Figure 11A, for example, SiO is stacked on the lower electrode 110. ｘ A low refractive index layer 130 made of [material] is laminated. Furthermore, as shown in the lower part of Figure 11A, for example, a reflector 140 made of Al is formed on the low refractive index layer 130.

[0100] Next, as shown in the upper part of Figure 11B, the fabricated laminated structure is inverted. Then, as shown in the second part from the top of Figure 11B, the compound semiconductor layer 124 is thinned. Then, as shown in the third part from the top of Figure 11B, a trench 170 is formed that penetrates the compound semiconductor layer 124, the active layer 120, and the compound semiconductor layer 122. Furthermore, as shown in the fourth part from the top of Figure 11B, for example, HSQ is embedded in the trench 170 to form a columnar body 126. Then, as shown in the lower part of Figure 11B, for example, an upper electrode 112 made of ITO is laminated so as to cover the columnar body 126. In this way, the light-emitting element 100 according to the first embodiment shown in Figure 4A can be obtained.

[0101] As described above, the light-emitting element 100 according to the embodiment of this disclosure can be manufactured using methods, apparatus, and conditions commonly used in the manufacture of semiconductor devices. In other words, the light-emitting element 100 according to this embodiment can be manufactured using existing semiconductor device manufacturing methods.

[0102] Examples of the methods mentioned above include the PVD (Physical Vapor Deposition) method, the CVD (Chemical Vapor Deposition) method, and the ALD (Atomic Layer Deposition) method. Examples of PVD methods include vacuum deposition, electron beam (EB) deposition, various sputtering methods (magnetron sputtering, RF (Radio Frequency)-DC (Direct Current) coupled bias sputtering, ECR (Electron Cyclotron Resonance) sputtering, counter-target sputtering, high-frequency sputtering, etc.), ion plating, laser ablation, molecular beam epitaxy (MBE (Molecular Beam Epitaxy)), and laser transfer. Examples of CVD methods include plasma CVD, thermal CVD, metal-organic (MO) CVD, and optical CVD. Furthermore, other methods include electrolytic plating, electroless plating, spin coating, immersion, casting, microcontact printing, drop casting, various printing methods such as screen printing, inkjet printing, offset printing, gravure printing, and flexographic printing, as well as stamping, spraying, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, transfer roll coater, gravure coater, kiss coater, cast coater, spray coater, slit orifice coater, and calender coater. In addition, patterning methods include chemical etching such as shadow masks, laser transfer, and photolithography, as well as physical etching using ultraviolet light or lasers. Furthermore, planarization techniques include CMP (Chemical Mechanical Polishing), laser planarization, and reflow.

[0103] Furthermore, the method for manufacturing the light-emitting element 100 according to the first embodiment is not limited to the example shown in Figures 11A and 11B.

[0104] <<11. Examples>> Hereinafter, embodiments of the present disclosure will be described based on examples with reference to Figures 12A to 12E. Figures 12A to 12E are explanatory diagrams for illustrating the examples. The embodiments of the present disclosure are not limited to the following examples. In Figures 12A, 12B, 12C, 12D, 12E and Table 1, the numerical values ​​relating to the diameter of the columnar body 126, the slab thickness (corresponding to the film thickness of the light-emitting layer 102), and the position within the photonic crystal structure 104 are normalized by the period length a of the columnar body 126.

[0105] Optical simulations were performed on an emissive layer 102 containing a photonic crystal structure 104 with a defect 128 introduced, as shown in Figure 12A. Specifically, FDTD (Finite Difference Time Domain) simulations were performed using Luméric from Ansys. The model of the photonic crystal structure 104 used is provided within the emissive layer 102 having a refractive index of 2.54, and has columnar bodies 126 with a refractive index of 1.47 and diameters of 0.26a and 0.28a. Furthermore, a defect 128 is provided in the center of the photonic crystal structure 104. Specifically, the y-z cross-section (film thickness direction) of the photonic crystal structure 104 used is shown on the left side of Figure 12A, and the x-y plane (planar direction) of the photonic crystal structure 104 used is shown on the right side of Figure 12A. Furthermore, optical simulations were performed by changing the diameter of the columnar body 126 and the slab thickness (corresponding to the film thickness of the light-emitting layer 102). In addition, in the optical simulations, residual light was observed approximately 3.75E-13 [sec] after the central part of the photonic crystal structure 104 was excited and coupled with the resonator formed by the defect 128.

[0106] Through these optical simulations, we were able to obtain the electric field distribution shown in Figure 12B and the radiation characteristics shown in Figure 12C. The results shown in Figures 12B and 12C are based on the conditions of No. 6 (Example) in Table 1. The electric field distribution shown in Figure 12B indicates that resonance occurs in the center of the photonic crystal structure 104. Furthermore, the radiation characteristics shown in Figure 12C indicate that a large amount of light is emitted upwards and forwards from the center of the photonic crystal structure 104.

[0107] Based on the simulation results obtained under the above conditions, a mode volume (V) of 0.9 or less was considered acceptable (indicated by a circle in Table 1). Conversely, a mode volume greater than 0.9 was considered unacceptable (indicated by an X in Table 1). This is because a smaller mode volume allows for the Purcell effect of the resonator to be expected.

[0108] Furthermore, based on the simulation results obtained under the above conditions, a ratio of 0.650 or higher of the light emitted upward from the light-emitting element 100 that is captured within NA 0.7 (emission angle ±44.4 degrees) was judged as passing the emission characteristics test (indicated by a circle in Table 1). On the other hand, a ratio of less than 0.650 was judged as failing the emission characteristics test (indicated by an X in Table 1). This index indicates the ratio of light that travels upward from the light-emitting element 100. The reason for using the ratio of light within NA 0.7 (emission angle ±44.4 degrees) as the criterion is that if the light travels within this range, it will be incident on the on-chip lens 152 located above the light-emitting element 100, and the light can be emitted as collimated light in front of the light-emitting element 100.

[0109] Furthermore, if the photonic crystal structure 104 meets the requirements for both mode volume (V) and radiation characteristics, it can be said that it is easier to efficiently increase the light intensity (brightness, color purity) and to control the direction of light propagation in the direction of the film thickness of the light-emitting layer 102 (control of the radiation angle). Table 1 shows the simulation results.

[0110] Table 1 shows that when the slab thickness, i.e., the film thickness of the light-emitting layer 102, is between 0.4a and 1.6a, the mode volume (V) is small and the radiation characteristics are good.

[0111] In other words, it was found that by setting the film thickness of the high refractive index light-emitting layer 102 sandwiched between the low refractive index layers 130 and 132 to 1.4 times or more and 1.6 times or less the period length a of the columnar body 126, more light can be confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102. Therefore, it was found that by doing so, the resonator formed by the defect 128 can be made to function efficiently.

[0112] <<12. Summary>> As described above, in each embodiment of the present disclosure, a photonic crystal structure 104 consisting of a periodic structure of a plurality of columnar bodies 126 is provided in the light-emitting layer 102, and defects 128 are introduced into the photonic crystal structure 104, and the defects 128 and the region surrounding the defects 128 function as an optical resonator. Furthermore, in each embodiment of the present disclosure, the film thickness t of the light-emitting layer 102 having a high refractive index sandwiched between the low refractive index layers 130 and 132 is set to 1.4 times or more and 1.6 times or less the period length a of the columnar bodies 126. By doing so, according to each embodiment of the present disclosure, more light can be confined within the light-emitting layer 102 in the direction of the film thickness of the light-emitting layer 102, so that the resonator due to the defects 128 can function efficiently. As a result, according to this embodiment, the intensity of light (brightness, color purity) can be increased more efficiently, and it is easier to control the direction in which light propagates in the direction of the film thickness of the light-emitting layer 102 (control of the radiation angle). In other words, according to each embodiment of the present disclosure, the utilization efficiency of light emission in the light-emitting element 100 can be further increased.

[0113] Furthermore, the display device 10 according to the embodiment of this disclosure can be applied to, for example, VR, MR, or AR display devices, smartphones, television devices, electronic viewfinders (EVFs), or small projectors. In addition, the display device 10 can also be applied to various lighting devices.

[0114] <<13. Modifications>> <13.1 Modification 1> Next, as a modification of the embodiment of the present disclosure, a modification concerning the relationship between the normal LN passing through the center of the light-emitting element 100, the normal LN' passing through the center of the lens structure (for example, the on-chip lens 152 provided on the light-emitting element 100), and the normal LN" passing through the center of the wavelength selection unit (for example, the color filter provided on the light-emitting element 100) will be described with reference to Figures 13A to 13G. Figures 13A to 13G are conceptual diagrams for explaining the relationship between the normal LN passing through the center of the light-emitting unit, the normal LN' passing through the center of the lens member, and the normal LN" passing through the center of the wavelength selection unit. In the following description, the center of the light-emitting element 100 will be referred to as the center of the light-emitting unit.

[0115] In embodiments of this disclosure, the size of the wavelength selection area may be appropriately changed in accordance with the light emitted by the light-emitting element 100. Furthermore, if a light-absorbing layer (black matrix layer) is provided between the wavelength selection area of ​​an adjacent light-emitting element 100, the size of the light-absorbing layer (black matrix layer) may be appropriately changed in accordance with the light emitted by the light-emitting element 100. In addition, the size of the wavelength selection area may be determined by the distance (offset amount) d between the normal passing through the center of the light-emitting element 100 and the normal passing through the center of the wavelength selection area. ０ Depending on the circumstances, it may be changed as appropriate. The planar shape of the wavelength selection section may be the same as, similar to, or different from the planar shape of the lens element.

[0116] For example, as shown in Figure 13A, the normal vector LN passing through the center of the light-emitting part, the normal vector LN'' passing through the center of the wavelength selection part, and the normal vector LN' passing through the center of the lens member may be made to coincide. In other words, the distance (offset amount) D between the normal vector passing through the center of the light-emitting part and the normal vector passing through the center of the lens member. ０ The distance (offset amount) d between the normal vector passing through the center of the light-emitting part and the normal vector passing through the center of the wavelength-selecting part. ０ This is equivalent to 0 (zero).

[0117] Furthermore, for example, as shown in Figure 13B, the normal vector LN passing through the center of the light-emitting part and the normal vector LN'' passing through the center of the wavelength-selecting part coincide, but the normal vector LN passing through the center of the light-emitting part and the normal vector LN'' passing through the center of the wavelength-selecting part do not have to coincide with the normal vector LN' passing through the center of the lens member. In other words, D ０ ≠d ０ It may also be equal to 0.

[0118] Furthermore, for example, as shown in Figure 13C, the normal vector LN passing through the center of the light-emitting part, the normal vector LN'' passing through the center of the wavelength-selecting part, and the normal vector LN' passing through the center of the lens member do not coincide, but the normal vector LN'' passing through the center of the wavelength-selecting part and the normal vector LN' passing through the center of the lens member may coincide. In other words, D ０ = d ０ It can also be 0.

[0119] Furthermore, as shown in Figure 13D, for example, the normal vector LN passing through the center of the light-emitting part, the normal vector LN'' passing through the center of the wavelength-selecting part, and the normal vector LN' passing through the center of the lens member do not coincide, and the normal vector LN' passing through the center of the lens member does not coincide with the normal vector LN passing through the center of the surface of the light-emitting part and the normal vector LN'' passing through the center of the wavelength-selecting part. Here, it is preferable that the center of the wavelength-selecting part (shown as a black circle in Figure 13D) is located on a straight line LL connecting the center of the surface of the light-emitting part and the center of the lens member (shown as a black circle in Figure 13D). Specifically, the distance from the center of the surface of the light-emitting part in the thickness direction to the center of the wavelength-selecting part is LL. １ The distance from the center of the wavelength selection area in the thickness direction to the center of the lens material is LL ２ In that case, D ０ >d ０ > 0, and considering manufacturing variations, d ０ : D ０ =LL １ : (LL １ +LL ２ It is preferable that the following conditions be satisfied.

[0120] Furthermore, the stacking relationship between the wavelength selection unit and the lens member may be reversed. In such a case, for example, as shown in Figure 13E, the normal vector LN passing through the center of the light-emitting unit, the normal vector LN'' passing through the center of the wavelength selection unit, and the normal vector LN' passing through the center of the lens member may be made to coincide. In other words, D ０ = d ０ It may also be equal to 0.

[0121] Furthermore, for example, as shown in Figure 13F, the normal vector LN passing through the center of the light-emitting part, the normal vector LN'' passing through the center of the wavelength-selecting part, and the normal vector LN' passing through the center of the lens member do not coincide, but the normal vector LN'' passing through the center of the wavelength-selecting part and the normal vector LN' passing through the center of the lens member may coincide. In other words, D ０ = d ０ It can also be 0.

[0122] Furthermore, as shown in the conceptual diagram Figure 13G, the normal vector LN passing through the center of the surface of the light-emitting part, the normal vector LN'' passing through the center of the wavelength-selecting part, and the normal vector LN' passing through the center of the lens member do not coincide, and the normal vector LN' passing through the center of the lens member does not coincide with the normal vector LN passing through the center of the surface of the light-emitting part and the normal vector LN'' passing through the center of the wavelength-selecting part. Here, it is preferable that the center of the wavelength-selecting part is located on the straight line LL connecting the center of the surface of the light-emitting part and the center of the lens member. Specifically, the distance from the center of the surface of the light-emitting part in the thickness direction to the center of the wavelength-selecting part (shown as a black circle in Figure 13G) is LL. １ The distance from the center of the wavelength selection area in the thickness direction to the center of the lens member (shown as a black circle in Figure 13G) is LL ２ When that happens, d ０ >D ０ > 0, and considering manufacturing variations, D ０ :d ０ =LL ２ : (LL １ +LL ２ It is preferable that the following conditions be satisfied.

[0123] <13.2 Modification 2> The subpixel 1100 (more specifically, the light-emitting element 100) used in the display device 10 according to the embodiment of the present disclosure described above may be configured to include a resonator structure (microcavity structure) that resonates the light generated in the light-emitting layer 102. The above resonator structure will be described below with reference to Figures 14 to 20. Figure 14 is a schematic cross-sectional view illustrating a first example of the resonator structure, Figure 15 is a schematic cross-sectional view illustrating a second example of the resonator structure, and Figure 16 is a schematic cross-sectional view illustrating a third example of the resonator structure. Furthermore, Figure 17 is a schematic cross-sectional view illustrating a fourth example of the resonator structure, and Figure 18 is a schematic cross-sectional view illustrating a fifth example of the resonator structure. Furthermore, Figure 19 is a schematic cross-sectional view illustrating a sixth example of the resonator structure, and Figure 20 is a schematic cross-sectional view illustrating a seventh example of the resonator structure. In the following explanation, the letters attached to each symbol indicate the corresponding color; specifically, "B" indicates blue, "G" indicates green, and "R" indicates red.

[0124] (Resonator structure: First example) Figure 14 is a schematic cross-sectional view illustrating the first example of a resonator structure. In the first example, the first electrode (specifically, the lower electrode 110) 1202 is formed with a common film thickness in each subpixel 1100. The same applies to the second electrode (specifically, the upper electrode 112) 1206.

[0125] As shown in Figure 14, a reflector (specifically, reflector 140) 1401 is positioned below the first electrode 1202 of the subpixel 1100, with an optical adjustment layer (specifically, a low refractive index layer 130) 1402 sandwiched in between. A resonator structure is formed between the reflector 1401 and the second electrode 1206 to resonate the light generated by the light-emitting layer (specifically, light-emitting layer 102) 1204.

[0126] The reflector 1401 is formed with a common film thickness for each subpixel 1100. The film thickness of the optical adjustment layer 1402 differs depending on the color that the subpixel 1100 is to display. By having optical adjustment layers 1402R, 1402G, and 1402B with different film thicknesses, it is possible to set the optical distance that produces the optimal resonance for the wavelength of light corresponding to the color to be displayed.

[0127] In the example shown in Figure 14, the upper surfaces of the reflectors 1401 for subpixels 1100R, 1100G, and 1100B are aligned. As described above, the thickness of the optical adjustment layer 1402 differs depending on the color that the subpixel 1100 should display, so the position of the upper surface of the second electrode 1206 differs depending on the type of subpixel 1100R, 1100G, and 1100B.

[0128] The reflector 1401 can be formed using, for example, a metal such as aluminum (Al), silver (Ag), or copper (Cu), or an alloy mainly composed of these metals.

[0129] The optical adjustment layer 1402 can be constructed using inorganic insulating materials such as silicon nitride (SiNx), silicon oxide (SiOx), or silicon oxynitride (SiOxNy), or organic resin materials such as acrylic resin or polyimide resin. The optical adjustment layer 1402 may be a single layer or a laminated film of multiple materials. Furthermore, the number of layers may vary depending on the type of subpixel 1100.

[0130] The first electrode 1202 can be formed using a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO).

[0131] The second electrode 1206 preferably functions as a semi-transparent reflective film. The second electrode 1206 can be formed using magnesium (Mg), silver (Ag), or a magnesium-silver alloy (MgAg) mainly composed of these, or an alloy containing alkali metals or alkaline earth metals.

[0132] (Resonator structure: Second example) Figure 15 is a schematic cross-sectional view illustrating a second example of the resonator structure. In this second example as well, the first electrode 1202 and the second electrode 1206 are formed with a common film thickness in each subpixel 1100.

[0133] In the second example as well, a reflector 1401 is placed beneath the first electrode 1202 of the subpixel 1100, with an optical adjustment layer 1402 in between. A resonator structure is formed between the reflector 1401 and the second electrode 1206 to resonate the light generated by the light-emitting layer 1204. Similar to the first example, the reflector 1401 is formed with a common film thickness for each subpixel 1100, while the film thickness of the optical adjustment layer 1402 differs according to the color that the subpixel 1100 should display.

[0134] In the first example shown in Figure 14, the upper surfaces of the reflectors 1401 in the subpixels 1100R, 1100G, and 1100B were aligned, while the position of the upper surface of the second electrode 1206 differed depending on the type of subpixel 1100R, 1100G, and 1100B.

[0135] In contrast, in the second example shown in Figure 15, the upper surface of the second electrode 1206 is arranged to align with the subpixels 1100R, 1100G, and 1100B. In order to align the upper surfaces of the second electrode 1206, the upper surface of the reflector 1401 is arranged differently for the subpixels 1100R, 1100G, and 1100B, depending on the type of subpixel. As a result, the lower surface of the reflector 1401 has a stepped shape depending on the type of subpixel 1100R, 1100G, and 1100B.

[0136] The materials and other components constituting the reflector 1401, the optical adjustment layer 1402, the first electrode 1202, and the second electrode 1206 are the same as those described in the first example, so their explanation will be omitted.

[0137] (Resonator structure: Third example) Figure 16 is a schematic cross-sectional view illustrating the third example of the resonator structure. In the third example as well, the first electrode 1202 and the second electrode 1206 are formed with a common film thickness in each subpixel 1100.

[0138] In the third example, the reflector 1401 is positioned below the first electrode 1202 of the subpixel 1100, with the optical adjustment layer 1402 in between. A resonator structure is formed between the reflector 1401 and the second electrode 1206 to resonate the light generated by the light-emitting layer 1204. Similar to the first and second examples, the thickness of the optical adjustment layer 1402 varies depending on the color that the subpixel 1100 should display. And, similar to the second example, the upper surface of the second electrode 1206 is positioned so that it aligns with the subpixels 1100R, 1100G, and 1100B.

[0139] In the second example shown in Figure 15, the lower surface of the reflector 1401 had a stepped shape corresponding to the type of sub-pixel 1100R, 1100G, and 1100B in order to align the upper surface of the second electrode 1206.

[0140] In contrast, in the third example shown in Figure 16, the film thickness of the reflector 1401 is set to differ depending on the type of sub-pixel 1100R, 1100G, and 1100B. More specifically, the film thickness is set so that the lower surfaces of the reflectors 1401R, 1401G, and 1401B are aligned.

[0141] The materials constituting the reflector 1401, the optical adjustment layer 1402, the first electrode 1202, and the second electrode 1206 are the same as those described in the first example, so their explanation will be omitted.

[0142] (Resonator structure: 4th example) Figure 17 is a schematic cross-sectional view illustrating the 4th example of a resonator structure.

[0143] In the first example shown in Figure 14, the first electrode 1202 and the second electrode 1206 of the subpixel 1100 are formed with a common film thickness. A reflector 1401 is placed below the first electrode 1202 of the subpixel 1100, with an optical adjustment layer 1402 in between.

[0144] In contrast, in the fourth example shown in Figure 17, the optical adjustment layer 1402 is omitted, and the film thickness of the first electrode 1202 is set to differ depending on the type of subpixel 1100R, 1100G, and 1100B.

[0145] The reflector 1401 is formed with a common film thickness for each subpixel 1100. The film thickness of the first electrode 1202 differs depending on the color that the subpixel 1100 is to display. By having the first electrodes 1202R, 1202G, and 1202B have different film thicknesses, it is possible to set the optical distance that produces the optimal resonance for the wavelength of light corresponding to the color to be displayed.

[0146] The materials constituting the reflector 1401, the first electrode 1202, and the second electrode 1206 are the same as those described in the first example, so their explanation will be omitted.

[0147] (Resonator structure: Fifth example) Figure 18 is a schematic cross-sectional view illustrating the fifth example of a resonator structure.

[0148] In the first example shown in Figure 14, the first electrode 1202 and the second electrode 1206 are formed with a common film thickness in each subpixel 1100. A reflector 1401 is placed below the first electrode 1202 of the subpixel 1100, with an optical adjustment layer 1402 in between.

[0149] In contrast, in the fifth example shown in Figure 18, the optical adjustment layer 1402 was omitted, and instead, an oxide film 1404 was formed on the surface of the reflector 1401. The thickness of the oxide film 1404 was set to differ depending on the type of subpixel 1100R, 1100G, and 1100B.

[0150] The thickness of the oxide film 1404 varies depending on the color that the subpixel 1100 is to display. By having oxide films 1404R, 1404G, and 1404B with different thicknesses, it is possible to set the optical distance that produces the optimal resonance for the wavelength of light corresponding to the color to be displayed.

[0151] The oxide film 1404 is a film obtained by oxidizing the surface of the reflector 1401, and is composed of, for example, aluminum oxide, tantalum oxide, titanium oxide, magnesium oxide, zirconium oxide, etc. The oxide film 1404 functions as an insulating film for adjusting the optical path length (optical distance) between the reflector 1401 and the second electrode 1206.

[0152] The oxide film 1404, which has a different thickness depending on the type of subpixel 1100R, 1100G, and 1100B, can be formed, for example, as follows.

[0153] First, the container is filled with electrolyte, and the substrate on which the reflector 1401 is formed is immersed in the electrolyte. Then, electrodes are positioned opposite the reflector 1401.

[0154] Then, a positive voltage is applied to the reflector 1401 with the electrode as the reference, and the reflector 1401 is anodized. The thickness of the oxide film formed by anodization is proportional to the voltage value applied to the electrode. Therefore, anodization is performed on each of the reflectors 1401R, 1401G, and 1401B with a voltage corresponding to the type of sub-pixel 1100R, 1100G, and 1100B applied. This makes it possible to form oxide films 1404 of different thicknesses all at once.

[0155] The materials constituting the reflector 1401, the first electrode 1202, and the second electrode 1206 are the same as those described in the first example, so their explanation will be omitted.

[0156] (Resonator Structure: Sixth Example) Figure 19 is a schematic cross-sectional view illustrating the sixth example of a resonator structure. In the sixth example, the subpixel 1100 is constructed by stacking a first electrode 1202, a light-emitting layer 1204, and a second electrode 1206. However, in the sixth example, the first electrode 1202 is formed to serve both as an electrode and a reflector. The first electrode (and reflector) 1202 is made of a material having optical constants selected according to the type of subpixel 1100R, 1100G, and 1100B. By different phase shifts caused by the first electrode (and reflector) 1202, it is possible to set an optical distance that produces optimal resonance for the wavelength of light corresponding to the color to be displayed.

[0157] The first electrode (and reflector) 1202 can be made from a single metal such as aluminum (Al), silver (Ag), gold (Au), or copper (Cu), or from an alloy mainly composed of these metals. For example, the first electrode (and reflector) 1202R of the subpixel 1100R can be made of copper (Cu), and the first electrode (and reflector) 1202G of the subpixel 1100G and the first electrode (and reflector) 1202B of the subpixel 1100B can be made of aluminum.

[0158] The materials and other components constituting the second electrode 1206 are the same as those described in the first example, so we will omit further explanation.

[0159] (Resonator Structure: Seventh Example) Figure 20 is a schematic cross-sectional view illustrating the seventh example of the resonator structure. The seventh example basically applies the sixth example to subpixels 1100R and 1100G, and the first example to subpixel 1100B. In this configuration as well, it is possible to set the optical distance that produces optimal resonance for the wavelength of light corresponding to the color to be displayed.

[0160] The first electrodes (which also serve as reflectors) 1202R and 1202G used in the sub-pixels 1100R and 1100G can be made from elemental metals such as aluminum (Al), silver (Ag), gold (Au), and copper (Cu), or alloys in which these metals are the main components.

[0161] The materials constituting the reflector 1401B, optical adjustment layer 1402B, and first electrode 1202B used in the subpixel 1100B are the same as those described in the first example, so their explanation will be omitted.

[0162] <<14. Examples of Application>> For example, the technology relating to this disclosure may be applied to the display units of various electronic devices. Therefore, examples of electronic devices to which this technology can be applied will be described below.

[0163] (Specific Example 1) Figure 21A is a front view showing an example of the external appearance of the digital still camera 500, and Figure 21B is a rear view showing an example of the external appearance of the digital still camera 500. This digital still camera 500 is a single-lens reflex type with interchangeable lenses, and has an interchangeable shooting lens unit (interchangeable lens) 512 located approximately in the center of the front of the camera body 511, and a grip portion 513 for the photographer to hold on the left side of the front.

[0164] A monitor 514 is provided on the back of the camera body 511, slightly to the left of the center. An electronic viewfinder (eyepiece) 515 is provided above the monitor 514. The photographer can determine the composition by looking through the electronic viewfinder 515 and visually confirming the light image of the subject guided by the shooting lens unit 512. The display device 10 according to the embodiment of this disclosure can be used as the monitor 514 and the electronic viewfinder 515.

[0165] (Specific Example 2) Figure 22 is an external view of a head-mounted display 600. The head-mounted display 600 has, for example, an eyeglass-shaped display unit 611 and ear hooks 612 on both sides for being attached to the user's head. In this head-mounted display 600, the display device 10 according to the embodiment of this disclosure can be used as the display unit 611.

[0166] (Specific Example 3) Figure 23 is an external view of the see-through head-mounted display 634. The see-through head-mounted display 634 consists of a main body 632, an arm 633, and a lens barrel 631.

[0167] The main body 632 is connected to the arm 633 and the eyeglasses 630. Specifically, the long end of the main body 632 is connected to the arm 633, and one side of the main body 632 is connected to the eyeglasses 630 via a connecting member. The main body 632 may also be directly attached to the head of a person.

[0168] The main body 632 houses a control board for controlling the operation of the see-through head-mounted display 634 and a display unit. The arm 633 connects the main body 632 to the lens barrel 631 and supports the lens barrel 631. Specifically, the arm 633 is connected to the end of the main body 632 and the end of the lens barrel 631, respectively, and fixes the lens barrel 631 in place. The arm 633 also houses signal lines for communicating image-related data provided from the main body 632 to the lens barrel 631.

[0169] The lens barrel 631 projects image light, provided from the main body 632 via the arm 633, through the eyepiece lens towards the eyes of the user wearing the see-through head-mounted display 634. In this see-through head-mounted display 634, the display device 10 according to the embodiment of this disclosure can be used in the display section of the main body 632.

[0170] (Specific Example 4) Figure 24 shows an example of the appearance of a television device 710. This television device 710 has, for example, a video display screen section 711 including a front panel 712 and a filter glass 713, and this video display screen section 711 is configured with a display device 10 according to the embodiment of this disclosure.

[0171] (Specific Example 5) Figure 25 shows an example of the appearance of a smartphone 800. The smartphone 800 has a display unit 802 that displays various information, and an operation unit consisting of buttons, etc. that accept user input. The display unit 802 may be the display device 10 according to this embodiment.

[0172] (Specific Example 6) Figures 26A and 26B show the internal configuration of an automobile having a display device 10 according to the embodiment of this disclosure as a display device. More specifically, Figure 26A shows the interior of the automobile from the rear to the front, and Figure 26B shows the interior of the automobile from the diagonally rear to the diagonally front.

[0173] The automobile shown in Figures 26A and 26B includes a center display 911, a console display 912, a head-up display 913, a digital rear mirror 914, a steering wheel display 915, and a rear entertainment display 916. Some or all of these displays can be fitted with the display device 10 according to the embodiment of this disclosure.

[0174] The center display 911 is positioned on the center console 907, facing the driver's seat 901 and the passenger seat 902. Figures 26A and 26B show an example of a horizontally elongated center display 911 extending from the driver's seat 901 to the passenger seat 902, but the screen size and placement of the center display 911 are arbitrary. The center display 911 can display information detected by various sensors (not shown). As a specific example, the center display 911 can display images captured by an image sensor, distance images to obstacles in front of or to the side of the vehicle measured by a ToF (Time of Flight) sensor, and the body temperature of passengers detected by an infrared sensor. The center display 911 can be used to display, for example, at least one of safety-related information, operation-related information, life logs, health-related information, authentication / identification-related information, and entertainment-related information.

[0175] Safety-related information includes information such as drowsiness detection, distraction detection, detection of mischief by a passenger, seatbelt fastening status, and detection of an unattended occupant. This information is detected, for example, by a sensor (not shown) placed on top of the back of the center display 1911. Operation-related information is detected by sensing occupant gestures using sensors. The detected gestures may include the operation of various equipment in the vehicle. For example, the sensor detects the operation of air conditioning equipment, navigation systems, AV (Audio / Visual) systems, lighting systems, etc. Life logs include the life logs of all occupants. For example, life logs include records of each occupant's actions while riding in the vehicle. By acquiring and saving life logs, it is possible to confirm the state of the occupants at the time of an accident. Health-related information is detected by sensing the occupant's body temperature using a temperature sensor and inferring the occupant's health status based on the detected body temperature. Alternatively, the occupant's face may be captured using an image sensor, and the occupant's health status may be inferred from the facial expression captured. Furthermore, the system may engage in automated voice conversations with the occupants and infer their health status based on their responses. Authentication / identification-related information includes keyless entry functions that use sensors for facial recognition and functions that automatically adjust seat height and position based on facial recognition. Entertainment-related information includes functions that use sensors to detect information on how the occupants operate the AV equipment and functions that use sensors to recognize the occupants' faces and provide content suitable for the occupants through the AV equipment.

[0176] The console display 912 can be used, for example, to display life log information. The console display 912 is located near the shift lever 908 on the center console 907 between the driver's seat 901 and the passenger seat 902. The console display 912 can also display information detected by various sensors (not shown). In addition, the console display 912 may display an image of the area around the vehicle captured by an image sensor, or it may display an image showing the distance to obstacles around the vehicle.

[0177] The head-up display 913 is virtually displayed behind the windshield 904 in front of the driver's seat 901. The head-up display 913 can be used to display at least one of the following: safety-related information, operation-related information, life logs, health-related information, authentication / identification-related information, and entertainment-related information. Because the head-up display 913 is often virtually positioned in front of the driver's seat 901, it is suitable for displaying information directly related to the operation of the vehicle, such as the vehicle's speed and fuel (battery) level.

[0178] The digital rearview mirror 914 can not only display what is behind the vehicle, but also what is happening to the passengers in the rear seat. By placing a sensor (not shown) on top of the back of the digital rearview mirror 914, it can be used, for example, to display life log information.

[0179] The steering wheel display 915 is positioned near the center of the steering wheel 906 of the automobile. The steering wheel display 915 can be used to display at least one of the following: safety-related information, operation-related information, life log, health-related information, authentication / identification-related information, and entertainment-related information. In particular, because the steering wheel display 915 is located near the driver's hands, it is suitable for displaying life log information such as the driver's body temperature, or information related to the operation of AV equipment, air conditioning equipment, etc.

[0180] The rear entertainment display 916 is mounted on the back of the driver's seat 901 and the passenger seat 902, and is intended for viewing by rear-seat passengers. The rear entertainment display 916 can be used to display at least one of the following: safety-related information, operation-related information, life logs, health-related information, authentication / identification-related information, and entertainment-related information. In particular, because the rear entertainment display 916 is in front of the rear-seat passengers, it displays information relevant to the rear-seat passengers. For example, it may display information related to the operation of AV equipment or air conditioning equipment, or it may display the results of measurements of the rear-seat passengers' body temperature, etc., taken by a temperature sensor (not shown).

[0181] <<15. Supplement>> Although preferred embodiments of the present disclosure have been described in detail with reference to the attached drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person with ordinary skill in the art of the present disclosure may conceive of various modifications or alterations within the scope of the technical idea described in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure.

[0182] Furthermore, the effects described herein are merely descriptive or illustrative and not limiting. In other words, the technology relating to this disclosure may produce other effects that will be apparent to those skilled in the art from the description herein, in addition to or in lieu of the effects described herein.

[0183] Furthermore, this technology can also take the following configurations: (1) A display device having a plurality of light-emitting elements arranged on a substrate, wherein each light-emitting element comprises: a light-emitting layer made of a high refractive index layer formed from a compound semiconductor; a photonic crystal structure including a periodic structure made of a plurality of columnar bodies provided in the light-emitting layer and a resonator made of defects that disrupt the periodic structure; and a pair of low refractive index layers sandwiching the light-emitting layer from above and below, wherein the thickness of the light-emitting layer is 0.4 times or more and 1.6 times or less the period length of the periodic structure. (2) The display device according to (1) above, wherein the refractive index of the high refractive index layer is greater than 2, and the refractive index of the low refractive index layer is 2 or less. (3) The display device according to (1) or (2) above, wherein each light-emitting element further comprises a first transparent conductive layer provided on one side of the light-emitting layer. (4) The display device according to (3) above, wherein the first transparent conductive layer is provided so as not to overlap with the resonator. (5) The display device according to (3), wherein the film thickness of the region of the first transparent conductive layer that overlaps with the resonator is thinner than the film thickness of the region of the first transparent conductive layer that does not overlap with the resonator. (6) The display device according to any one of (3) to (5), wherein the plurality of columnar bodies penetrate the first transparent conductive layer along the film thickness direction of the first transparent conductive layer. (7) The display device according to any one of (1) to (6), wherein each light-emitting element further comprises a second transparent conductive layer provided on the other side of the light-emitting layer. (8) The display device according to (7), wherein the second transparent conductive layer is provided so as not to overlap with the resonator. (9) The display device according to (7), wherein the film thickness of the region of the second transparent conductive layer that overlaps with the resonator is thinner than the film thickness of the region of the second transparent conductive layer that does not overlap with the resonator. (10) The display device according to any one of (7) to (9) above, wherein the plurality of columnar bodies penetrate the second transparent conductive layer along the film thickness direction of the second transparent conductive layer. (11) The display device according to (1) or (2) above, wherein each light-emitting element is provided on at least one of one of the surfaces of the light-emitting layer and further comprises an insulating layer that does not overlap with the resonator.(12) The display device according to any one of (1) to (11), wherein the plurality of columnar bodies penetrate the entire light-emitting layer along the thickness of the light-emitting layer. (13) The display device according to (1) or (2), wherein the plurality of columnar bodies penetrate a part of the light-emitting layer along the thickness of the light-emitting layer. (14) The display device according to any one of (1) to (13), wherein the low refractive index layer is made of a laminate of different materials. (15) The display device according to any one of (1) to (14), wherein the resonator is provided in the center of the photonic crystal structure. (16) The display device according to any one of (1) to (15), wherein each light-emitting element further comprises a reflective layer provided on the side of one of the pair of low refractive index layers opposite to the light-emitting layer. (17) The display device according to any one of (1) to (16), wherein the light-emitting layer consists of a first compound semiconductor layer, an active layer, and a second compound semiconductor layer. (18) The display device according to (17) above, wherein the active layer has a single quantum well structure or a multiple quantum well structure. (19) The display device according to any one of (1) to (18) above, wherein the light-emitting layer is made of a GaN-based compound semiconductor, an AlGaInAs-based compound semiconductor, an AlGaInP-based compound semiconductor, a ZnSe-based compound semiconductor, or a ZnO-based compound semiconductor.

[0184] 10 Display device 11 Horizontal drive circuit 12 Vertical drive circuit 20 Pixel array section 40 Display panel 100 Light-emitting element 102 Light-emitting layer 104 Photonic crystal structure 120 Active layer 122, 124 Compound semiconductor layer 126 Columnar body 128 Defect 110 Lower electrode 110a, 112a Aperture 112 Upper electrode 112b Recess 130, 132, 134 Low refractive index layer 140 Reflector 150 Substrate 152 On-chip lens 160, 162 Insulating layer 170 Trench 400, 400B, 400G, 400R Subpixel

Claims

1. A display device having a plurality of light-emitting elements arranged on a substrate, wherein each light-emitting element comprises: a light-emitting layer made of a high refractive index layer formed from a compound semiconductor; a photonic crystal structure including a periodic structure made of a plurality of columnar bodies provided in the light-emitting layer and a resonator made of defects that disrupt the periodic structure; and a pair of low refractive index layers sandwiching the light-emitting layer from above and below, wherein the thickness of the light-emitting layer is 0.4 times or more and 1.6 times or less the period length of the periodic structure.

2. The display device according to claim 1, wherein the refractive index of the high refractive index layer is greater than 2, and the refractive index of the low refractive index layer is 2 or less.

3. The display device according to claim 1, wherein each light-emitting element further comprises a first transparent conductive layer provided on one side of the light-emitting layer.

4. The display device according to claim 3, wherein the first transparent conductive layer is provided so as not to overlap with the resonator.

5. The display device according to claim 3, wherein the film thickness of the region of the first transparent conductive layer that overlaps with the resonator is thinner than the film thickness of the region of the first transparent conductive layer that does not overlap with the resonator.

6. The display device according to claim 3, wherein the plurality of columnar bodies penetrate the first transparent conductive layer along the thickness direction of the first transparent conductive layer.

7. The display device according to claim 1, wherein each light-emitting element further comprises a second transparent conductive layer provided on the other side of the light-emitting layer.

8. The display device according to claim 7, wherein the second transparent conductive layer is provided so as not to overlap with the resonator.

9. The display device according to claim 7, wherein the film thickness of the region of the second transparent conductive layer that overlaps with the resonator is thinner than the film thickness of the region of the second transparent conductive layer that does not overlap with the resonator.

10. The display device according to claim 7, wherein the plurality of columnar bodies penetrate the second transparent conductive layer along the film thickness direction of the second transparent conductive layer.

11. The display device according to claim 1, wherein each light-emitting element is provided on at least one of the one and the other surface of the light-emitting layer and further comprises an insulating layer that does not overlap with the resonator.

12. The display device according to claim 1, wherein the plurality of columnar bodies penetrate the entire light-emitting layer along the thickness of the light-emitting layer.

13. The display device according to claim 1, wherein the plurality of columnar bodies penetrate a portion of the light-emitting layer along the thickness of the light-emitting layer.

14. The display device according to claim 1, wherein the low refractive index layer is made of a lamination of different materials.

15. The display device according to claim 1, wherein the resonator is located in the center of the photonic crystal structure.

16. The display device according to claim 1, wherein each light-emitting element further comprises a reflective layer provided on the side of one of the pair of low refractive index layers opposite to the light-emitting layer.

17. The display device according to claim 1, wherein the light-emitting layer comprises a first compound semiconductor layer, an active layer, and a second compound semiconductor layer.

18. The display device according to claim 17, wherein the active layer has a single quantum well structure or a multiple quantum well structure.

19. The display device according to claim 1, wherein the light-emitting layer is made of a GaN-based compound semiconductor, an AlGaInAs-based compound semiconductor, an AlGaInP-based compound semiconductor, a ZnSe-based compound semiconductor, or a ZnO-based compound semiconductor.

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