Light-emitting device and method for driving the light-emitting device

Abstract

To reduce fluctuations in the wavelength of light emitted from light-emitting elements due to heat generation. [Solution] The light-emitting device comprises a support substrate, a light-emitting element having a plurality of light-emitting layers arranged on the support substrate at mutually different distances from the support substrate, and a drive unit that switches the light emission of the plurality of light-emitting layers individually, wherein the plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located further from the support substrate than the first light-emitting layer, and the drive unit drives the light-emitting element such that the period during which the first light-emitting layer emits light continuously over time is longer than the period during which the second light-emitting layer emits light continuously over time.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting device and a driving method for the light-emitting device. Background Art

[0002] Conventionally, light-emitting elements such as LEDs (Light Emitting Diodes) have been widely used (see, for example, Patent Document 1). Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese National Publication of International Patent Application No. 2009-510762 Summary of the Invention Problem to be Solved by the Invention

[0004] However, in a light-emitting device using LEDs, heat generation may cause fluctuation in the peak wavelength of light emitted from the light-emitting element.

[0005] An object of an embodiment according to the present disclosure is to reduce fluctuation in the peak wavelength of light emitted from a light-emitting element caused by heat generation of the light-emitting element. Means for Solving the Problem

[0006] A light-emitting device according to an embodiment of the present disclosure includes: a support substrate; a light-emitting element which is disposed on the support substrate and has a plurality of light-emitting layers disposed such that distances thereof from the support substrate are different from each other; and a driving unit that individually switches light emission of the plurality of light-emitting layers, wherein the plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located farther from the support substrate than the first light-emitting layer, and the driving unit drives the light-emitting element such that a period in which the first light-emitting layer is caused to continuously emit light over time is longer than a period in which the second light-emitting layer is caused to continuously emit light over time. Effects of the Invention

[0007] According to the embodiments of this disclosure, it is possible to reduce fluctuations in the peak wavelength of light emitted from the light-emitting element due to heat generation from the light-emitting element. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the overall configuration of the light-emitting device according to the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the configuration of a light-emitting element and a support substrate in a light-emitting device according to the first embodiment. [Figure 3] This is a schematic cross-sectional view showing how a power supply is connected to the light-emitting element of the light-emitting device according to the first embodiment. [Figure 4] This is a timing diagram showing an example of a driving method by the drive unit of the light-emitting device according to the first embodiment. [Figure 5] This is a schematic top view showing the light-emitting element of a light-emitting device according to Modification 1 of the First Embodiment. [Figure 6] This is a schematic cross-sectional view showing the cross-section along the VV line in Figure 5. [Figure 7A] This is a schematic cross-sectional view showing the current path in the first light-emitting state of the light-emitting element of the light-emitting device according to Modification 1 of the first embodiment. [Figure 7B] This is a schematic cross-sectional view showing the current path in the second light-emitting state of the light-emitting element of the light-emitting device according to Modification 1 of the first embodiment. [Figure 7C] This is a schematic cross-sectional view showing the current path in the third light-emitting state of the light-emitting element of the light-emitting device according to Modification 1 of the first embodiment. [Figure 8] This is a schematic cross-sectional view showing the configuration of the light-emitting element and support substrate of a light-emitting device according to a modified example 2 of the first embodiment. [Figure 9] This is a block diagram showing the overall configuration of the light-emitting device according to the second embodiment. [Figure 10] This is a schematic cross-sectional view showing how a power supply is connected to the light-emitting element of the light-emitting device according to the second embodiment. [Figure 11]This is a timing diagram showing an example of a driving method by the drive unit of the light-emitting device according to the second embodiment. [Modes for carrying out the invention]

[0009] A light-emitting device according to the embodiments of this disclosure will be described in detail with reference to the drawings. However, the embodiments shown below are illustrative of light-emitting devices that embody the technical concept of this disclosure and are not limited thereto. Furthermore, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of this disclosure to those described therein, unless otherwise specified, but are merely illustrative examples. Note that the size, positional relationships, etc. of the members shown in each drawing may be exaggerated for clarity of explanation. In addition, in the following description, the same name and reference numeral indicate the same or similar members, and detailed explanations will be omitted as appropriate. In some cases, end view diagrams showing only the cut surface will be used as cross-sectional views.

[0010] In the diagrams shown below, directions may be indicated by the X, Y, and Z axes. The X, Y, and Z axes are mutually orthogonal. In the Z-axis direction, the direction indicated by the arrow may be labeled as upward, and the opposite direction may be labeled as downward.

[0011] [First Embodiment] <Configuration of the light-emitting device 100> Figure 1 is a block diagram showing an example of the overall configuration of the light-emitting device 100 according to the first embodiment. Figure 2 is a schematic cross-sectional view showing the configuration of the light-emitting element 110 and the support substrate 18 of the light-emitting device 100 according to the first embodiment. Figure 3 is a schematic cross-sectional view showing the light-emitting element 110 of the light-emitting device 100 connected to a power supply.

[0012] As shown in FIGS. 1 to 3, the light-emitting device 100 includes a light-emitting element 110 including a support substrate 18, and a plurality of light-emitting layers 2 disposed on the support substrate 18 at different distances from the support substrate 18, and a driving unit 120 that individually switches light emission of the plurality of light-emitting layers 2. The plurality of light-emitting layers 2 include a first light-emitting layer 21 and a second light-emitting layer 22 located farther from the support substrate 18 than the first light-emitting layer 21. In FIGS. 1 to 3, in order to show that the plurality of light-emitting layers 2 include the first light-emitting layer 21 and the second light-emitting layer 22, reference numerals for each of the first light-emitting layer 21, the second light-emitting layer 22, and the plurality of light-emitting layers 2 are given together. In the drawings shown hereinafter, reference numerals may be given together for the same purpose.

[0013] In a light-emitting device, when a light-emitting element is driven, the light-emitting element emits light and generates heat. When the light-emitting element generates heat and the temperature of the light-emitting element rises, the peak wavelength of light emitted from the light-emitting element may shift to the longer wavelength side.

[0014] In the light-emitting device 100, the driving unit 120 drives the light-emitting element 110 such that a period in which the first light-emitting layer 21 continuously emits light is longer than a period in which the second light-emitting layer 22 continuously emits light. Compared with the second light-emitting layer 22 located farther from the support substrate 18 than the first light-emitting layer 21, the first light-emitting layer 21 dissipates heat more easily toward the support substrate 18. Accordingly, in the light-emitting device 100, heat generation of the second light-emitting layer 22 can be reduced, and a temperature increase of the light-emitting element 110 can be reduced. As a result, fluctuation in the peak wavelength of light emitted from the light-emitting element 110 can be reduced. The period during which the first light-emitting layer 21 emits light and the period during which the second light-emitting layer 22 emits light in the light-emitting device 100 will be described later with reference to FIG. 4.

[0015] In the example shown in Figure 2, the light-emitting element 110 includes an element substrate 1 and a semiconductor laminate 1000 disposed on the element substrate 1. The semiconductor laminate 1000 is arranged in the following order from the element substrate 1 side: a first n-type semiconductor layer 20, a first p-type semiconductor layer 30, a superlattice layer 40 containing p-type impurities, a first light-emitting layer 21, a second n-type semiconductor layer 60, a second light-emitting layer 22, and a second p-type semiconductor layer 80. The second light-emitting layer 22 is located further from the support substrate 18 than the first light-emitting layer 21. In the example shown in Figure 2, the second light-emitting layer 22 is located above the first light-emitting layer 21 and is laminated on the first light-emitting layer 21 via the second n-type semiconductor layer 60. The first n-type semiconductor layer 20 is tunnel-junctioned with the first p-type semiconductor layer 30. In this specification, the p-type semiconductor layers (i.e., the first p-type semiconductor layer 30, the second p-type semiconductor layer 80 described later, and the third p-type semiconductor layer 92 described later) contain p-type impurities (e.g., Mg). The n-type semiconductor layers (i.e., the first n-type semiconductor layer 20, the second n-type semiconductor layer 60, the third n-type semiconductor layer 91 described later, and the fourth n-type semiconductor layer 93 described later) contain n-type impurities (e.g., Si).

[0016] The light-emitting element 110 is positioned on the support substrate 18 with its element substrate 1 facing the support substrate 18. The light-emitting element 110 is positioned on the support substrate 18, for example, via an adhesive member 95. The support substrate 18 has a base material 181 and a plurality of wiring layers 182 positioned on the base material 181. The first electrode 11, second electrode 12, and third electrode 13 of the light-emitting element 110 are each electrically connected to the wiring layer 182 via wires 96. The material of the base material 181 may be a ceramic material such as aluminum nitride or aluminum oxide, or a metallic material such as copper. If the base material 181 is made of a metallic material, an insulating layer can be placed between the base material 181 and the wiring layer 182.

[0017] Each layer of the semiconductor stack 1000 is composed of a nitride semiconductor. In this specification, a nitride semiconductor refers to a binary to quaternary semiconductor containing at least one of Al, Ga, and In and N, and In x Al y Ga 1-x-yThe chemical formula N (0≦x≦1, 0≦y≦1, x+y≦1) may contain semiconductors of all compositions obtained by varying the composition ratios x and y within their respective ranges.

[0018] The first light-emitting layer 21 and the second light-emitting layer 22 emit light with an emission peak wavelength of 200 nm to 760 nm. That is, the first light-emitting layer 21 and the second light-emitting layer 22 emit ultraviolet light or visible light such as blue, green, or yellow. Both the first light-emitting layer 21 and the second light-emitting layer 22 can emit ultraviolet light. However, it is not limited to this, one of the first light-emitting layer 21 and the second light-emitting layer 22 can emit ultraviolet light and the other can emit visible light. Also, both the first light-emitting layer 21 and the second light-emitting layer 22 can emit visible light. When both the first light-emitting layer 21 and the second light-emitting layer 22 emit ultraviolet light, or when both emit visible light, the emission peak wavelengths emitted from the first light-emitting layer 21 and the emission peak wavelengths emitted from the second light-emitting layer 22 may be the same or different.

[0019] When the emission peak wavelengths emitted by the first light-emitting layer 21 and the second light-emitting layer 22 are different, the emission peak wavelength emitted by the first light-emitting layer 21 can be made shorter than that emitted by the second light-emitting layer 22 in terms of the amount of light extracted. Since the first light-emitting layer 21, with its shorter emission peak wavelength, has lower luminescence efficiency than the second light-emitting layer 22, with its longer emission peak wavelength, the amount of light extracted from the first light-emitting layer 21 can be increased by extending the duration for which the first light-emitting layer 21 emits light.

[0020] The first light-emitting layer 21 and the second light-emitting layer 22 may be a multiple quantum well structure having a plurality of well layers and a plurality of barrier layers, or they may be a single quantum well structure including one well layer and barrier layers on both sides thereof. When the first light-emitting layer 21 and the second light-emitting layer 22 are single or multiple quantum wells, the well layers are made of, for example, GaN, InGaN, or AlGaN. The barrier layers are made of, for example, AlGaN or GaN.

[0021] The element substrate 1 is made of, for example, sapphire, Si, SiC, or GaN. The element substrate 1 can be used as a substrate for arranging the first n-type semiconductor layer 20 included in the semiconductor stack 1000.

[0022] The light-emitting element 110 further includes a first electrode 11 disposed on a first n-type semiconductor layer 20, a second electrode 12 disposed on a second n-type semiconductor layer 60, and a third electrode 13 disposed on a second p-type semiconductor layer 80. The first electrode 11 is electrically connected to the first n-type semiconductor layer 20. The second electrode 12 is electrically connected to the second n-type semiconductor layer 60. The third electrode 13 is electrically connected to the second p-type semiconductor layer 80.

[0023] The first electrode 11 and the second electrode 12 can be made of metals such as Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, Al, Cu, or alloys containing these metals. The first electrode 11 and the second electrode 12 may be single-layer structures or laminated structures with multiple layers stacked on top of each other. For example, the first electrode 11 and the second electrode 12 can be laminated structures in which a Ti layer, an Al-Si-Cu alloy layer, a Ti layer, a Pt layer, an Au layer, and a Ti layer are stacked in this order.

[0024] In the example shown in Figure 2, the third electrode 13 includes a pad electrode 13a and an electrode layer 13b positioned in contact with the second p-type semiconductor layer 80. The electrode layer 13b can be made of a translucent metal oxide such as ITO, ZnO, IZO, or In2O3, or a light-reflective material such as silver. By using a translucent material as the electrode layer 13b, light can be emitted from the second p-type semiconductor layer 80 side. The pad electrode 13a can be made of a metal such as Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, Al, or Cu, or an alloy containing these metals.

[0025] In the example shown in Figure 3, the first electrode 11 and the second electrode 12 are electrically connected to the first power supply 25-1, respectively. The second electrode 12 and the third electrode 13 are electrically connected to the second power supply 25-2, respectively. The first electrode 11 and the third electrode 13 are anode electrodes. The second electrode 12 is a cathode electrode. When a voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, current flows from the first electrode 11 through the first light-emitting layer 21 to the second electrode 12, causing the first light-emitting layer 21 to emit light. When a voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, current flows from the third electrode 13 through the second light-emitting layer 22 to the second electrode 12, causing the second light-emitting layer 22 to emit light. The first power supply 25-1 and the second power supply 25-2 are components included in the drive unit 120.

[0026] The drive unit 120 can individually switch the light emission of the first light-emitting layer 21 and the second light-emitting layer 22 by switching between a state in which current flows from the first electrode 11 to the second electrode 12, or a state in which current flows from the third electrode 13 to the second electrode 12.

[0027] <Driving method using the drive unit 120> Figure 4 is a timing diagram showing an example of a driving method by the drive unit 120 of the light-emitting device 100. The upper part of Figure 4 shows the change in signal intensity of the first drive signal Dr1, which causes the first light-emitting layer 21 to emit light, according to time t. The graph shown by the thick solid line corresponds to the first drive signal Dr1. When the signal intensity of the first drive signal Dr1 is High (H), a voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, causing the first light-emitting layer 21 to emit light, i.e., to light up. On the other hand, when the signal intensity of the first drive signal Dr1 is Low (L), no voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, and the first light-emitting layer 21 does not emit light, i.e., it turns off.

[0028] Furthermore, the lower part of Figure 4 shows the change in signal intensity of the second drive signal Dr2, which causes the second light-emitting layer 22 to emit light, with respect to time t. The graph shown by the thick solid line corresponds to the second drive signal Dr2. When the signal intensity of the second drive signal Dr2 is High (H), a voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, causing the second light-emitting layer 22 to emit light, i.e., to light up. On the other hand, when the signal intensity of the second drive signal Dr2 is Low (L), no voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, and the second light-emitting layer 22 does not emit light, i.e., it turns off.

[0029] As shown in Figure 4, in the light-emitting device 100, the drive unit 120 drives the light-emitting element 110 such that the period T1 during which the first light-emitting layer 21 continuously emits light is longer than the period T2 during which the second light-emitting layer 22 continuously emits light. From the viewpoint of heat dissipation, it is preferable for the drive unit 120 to emit light from the first light-emitting layer 21 first. By having the first light-emitting layer 21 emit light first, followed by the second light-emitting layer 22, the heat generated when the first light-emitting layer 21 emits light is transferred to the element substrate 1 when the second light-emitting layer 22 emits light. Conversely, if the second light-emitting layer emits light first, the heat generated when the second light-emitting layer 22 emits light during the emission of the first light-emitting layer is blocked by the first light-emitting layer 21 and is not easily dissipated.

[0030] In the light-emitting device 100, the first light-emitting layer 21 and the second light-emitting layer 22 are driven such that the period T1 during which the first light-emitting layer 21, which dissipates heat more easily through the support substrate 18 compared to the second light-emitting layer 22, emits light is longer than the period T2 during which the second light-emitting layer 22 emits light. As a result, the light-emitting device 100 can reduce the heat generated by the second light-emitting layer 22 and reduce the temperature rise of the light-emitting element 110. By reducing the temperature rise of the light-emitting element 110, the light-emitting device 100 can reduce fluctuations in the peak wavelength of the light emitted from the light-emitting element 110.

[0031] In light-emitting elements that emit ultraviolet light, the fluctuation in the peak wavelength of the emitted light becomes more pronounced due to the heat generated by the light-emitting element compared to light-emitting elements that emit visible light. In the light-emitting device 100, a significant effect can be obtained in reducing the fluctuation in the peak wavelength of the light emitted from such an ultraviolet light-emitting element 110.

[0032] The drive unit 120 can switch the light emission of the first light-emitting layer 21 and the second light-emitting layer 22 throughout the entire period of continuous operation, thereby enabling continuous light emission from the light-emitting element 110. As a result, the light-emitting device 100 can emit light continuously without interruption.

[0033] The drive unit 120 sequentially performs a first control to drive the light-emitting element 110 so that the first light-emitting layer 21 emits light but the second light-emitting layer 22 does not emit light, and a second control to drive the light-emitting element 110 so that the second light-emitting layer 22 emits light but the first light-emitting layer 21 does not emit light. Specifically, in Figure 4, the drive unit 120 performs the first control during the period from time t10 to time t11 and from time t12 to time t13. The drive unit 120 also performs the second control during the period from time t11 to time t12 and from time t13 to time t14. Through these controls, the light-emitting device 100 can emit light continuously without interruption.

[0034] The drive unit 120 can exclusively switch the light emission of the first light-emitting layer 21 and the second light-emitting layer 22. As a result, the light-emitting device 100 can emit light continuously without interruption.

[0035] In the light-emitting device 100, a single light-emitting element having two light-emitting layers (a first light-emitting layer 21 and a second light-emitting layer 22) is arranged on a support substrate. Therefore, compared to a light-emitting device having a configuration in which a light-emitting element having a first light-emitting layer and a light-emitting element having a second light-emitting layer are arranged side by side on a support substrate, miniaturization is possible. Miniaturizing the light-emitting device 100 increases the flexibility of arranging the light-emitting device 100 in various devices, and also makes it easier to design optical elements such as lenses used in combination with the light-emitting device 100.

[0036] The drive unit 120 drives the light-emitting element 110 such that the period during which the first light-emitting layer 21 continuously emits light is longer than the period during which the second light-emitting layer 22 continuously emits light. In this case, the current supplied to the first light-emitting layer 21 can be the same as the current supplied to the second light-emitting layer 22. However, it is not limited to this, and for example, the drive unit 120 can drive the light-emitting element 110 such that the period during which the first light-emitting layer 21 continuously emits light is the same as or longer than the period during which the second light-emitting layer 22 continuously emits light, and the current supplied to the first light-emitting layer 21 is greater than the current supplied to the second light-emitting layer 22.

[0037] The support substrate 18 does not necessarily have to have a wiring layer 182. If the support substrate 18 does not have a wiring layer 182, the light-emitting device 100 may have, for example, a second support substrate having a wiring layer, which is positioned below the support substrate 18 (first support substrate). The wiring layer of the second support substrate is electrically connected to the electrodes of the light-emitting element 110.

[0038] The drive unit 120 may not only continuously emit light from the first light-emitting layer 21 during the period in which the first light-emitting layer 21 is emitted, but may also emit light intermittently. Similarly, the drive unit 120 may not only continuously emit light from the second light-emitting layer 22 during the period in which the second light-emitting layer 22 is emitted, but may also emit light intermittently.

[0039] In the example shown in Figure 4, the drive unit 120 switches the emission of light from the first light-emitting layer 21 and the second light-emitting layer 22 multiple times. However, the drive unit 120 is not limited to this, and may switch the emission of light from the first light-emitting layer 21 and the second light-emitting layer 22 only once.

[0040] <Modification 1 of the first embodiment> (Configuration of the light-emitting element of the light-emitting device according to a modified example of the first embodiment) Figure 5 is a schematic top view showing the light-emitting element 110a of the light-emitting device according to Modification 1 of the First Embodiment. Figure 6 is a schematic cross-sectional view showing the cross-section along the VV line in Figure 5.

[0041] As shown in Figures 5 and 6, the light-emitting element 110a comprises a semiconductor laminate 10-1, a first electrode 21-1, a second electrode 22-1, a third electrode 23-1, a first wiring 31-1, a second wiring 32-1, and a third wiring 33-1. As shown in Figure 5, the shape of the light-emitting element 110a in a top view is rectangular.

[0042] In the example shown in Figure 6, the semiconductor stack 10-1 includes a first p-type semiconductor layer 11a, a first light-emitting layer 21, a first n-type semiconductor layer 11c, an intermediate layer 13-1, a second p-type semiconductor layer 12a, a second light-emitting layer 22, and a second n-type semiconductor layer 12c.

[0043] The first p-type semiconductor layer 11a is located at the bottom of the semiconductor stack 10-1. The first light-emitting layer 21 is located on top of the first p-type semiconductor layer 11a. The first n-type semiconductor layer 11c is located on top of the first light-emitting layer 21. The intermediate layer 13-1 is located on top of the first n-type semiconductor layer 11c. The second p-type semiconductor layer 12a is located on top of the intermediate layer 13-1. The second light-emitting layer 22 is located on top of the second p-type semiconductor layer 12a. The second n-type semiconductor layer 12c is located on top of the second light-emitting layer 22.

[0044] Each layer of the semiconductor stack 10-1 is made of, for example, a nitride semiconductor. The intermediate layer 13-1 includes at least one of a p-type semiconductor layer having a higher p-type impurity concentration than the second p-type semiconductor layer 12a and an n-type semiconductor layer having a higher n-type impurity concentration than the first n-type semiconductor layer 11c. The intermediate layer 13-1 functions, for example, as a tunnel junction layer.

[0045] The semiconductor laminate 10-1 has a plurality of first apertures 16 and a plurality of second apertures 17. The plurality of first apertures 16 are arranged continuously in the first p-type semiconductor layer 11a, the first light-emitting layer 21, and the first n-type semiconductor layer 11c. The plurality of first apertures 16 are holes that penetrate the first p-type semiconductor layer 11a and the first light-emitting layer 21 in the Z-axis direction and reach the first n-type semiconductor layer 11c. The plurality of first apertures 16 do not penetrate the first n-type semiconductor layer 11c. The plurality of second apertures 17 are arranged continuously in the first p-type semiconductor layer 11a, the first light-emitting layer 21, the first n-type semiconductor layer 11c, the intermediate layer 13-1, the second p-type semiconductor layer 12a, the second light-emitting layer 22, and the second n-type semiconductor layer 12c. The multiple second apertures 17 are holes that penetrate the first p-type semiconductor layer 11a, the first light-emitting layer 21, the first n-type semiconductor layer 11c, the intermediate layer 13-1, the second p-type semiconductor layer 12a, and the second light-emitting layer 22 in the Z-axis direction, and reach the second n-type semiconductor layer 12c. The multiple second apertures 17 do not penetrate the second n-type semiconductor layer 12c.

[0046] In the light-emitting element 110a, the top-view shapes of the multiple first apertures 16 and the multiple second apertures 17 are each perfectly circular. However, the top-view shapes of the multiple first apertures 16 and the multiple second apertures 17 may also be elliptical, polygonal, or the like.

[0047] The first electrode 21-1 is electrically connected to the first p-type semiconductor layer 11a. In a top view, the first electrode 21-1 is located away from the semiconductor stack 10-1. The first electrode 21-1 does not overlap with the semiconductor stack 10-1 in the Z-axis direction.

[0048] The second electrode 22-1 is electrically connected to the second n-type semiconductor layer 12c. In a top view, the second electrode 22-1 is positioned away from the semiconductor stack 10-1. In the Z-axis direction, the second electrode 22-1 does not overlap with the semiconductor stack 10-1. For example, in a top view, the second electrode 22-1 is positioned diagonally to the first electrode 21-1.

[0049] The third electrode 23-1 is electrically connected to the first n-type semiconductor layer 11c. The third electrode 23-1 is located, for example, below the semiconductor stack 10-1. In the light-emitting element 110a, the third electrode 23-1 is located at the bottom of the light-emitting element 110a. In the light-emitting element 110a, the third electrode 23-1 is located below the semiconductor stack 10-1, the first electrode 21-1, the second electrode 22-1, the first wiring 31-1, the second wiring 32-1, and the third wiring 33-1.

[0050] The first wiring 31-1 electrically connects the first electrode 21-1 and the first p-type semiconductor layer 11a. The first wiring 31-1 is located below the semiconductor stack 10-1 (first p-type semiconductor layer 11a). In the light-emitting element 110a, the first wiring 31-1 and the first p-type semiconductor layer 11a are electrically connected via a contact electrode 25 located between the first wiring 31-1 and the first p-type semiconductor layer 11a.

[0051] The second wiring 32-1 electrically connects the second electrode 22-1 and the second n-type semiconductor layer 12c. The second wiring 32-1 extends from the second electrode 22-1, passes under the semiconductor laminate 10-1, and reaches the second opening 17. Upon reaching the second opening 17, the second wiring 32-1 comes into contact with the second n-type semiconductor layer 12c. In the light-emitting element 110a, the second wiring 32-1 and the second n-type semiconductor layer 12c are electrically connected by the contact between the second wiring 32-1 and the second n-type semiconductor layer 12c.

[0052] The third wiring 33-1 electrically connects the third electrode 23-1 and the first n-type semiconductor layer 11c. The third wiring 33-1 is arranged in multiple first apertures 16. In the light-emitting element 110a, the third wiring 33-1 is located below the first n-type semiconductor layer 11c. In the light-emitting element 110a, the third wiring 33-1 and the first n-type semiconductor layer 11c are electrically connected by contact between them.

[0053] The light-emitting element 110a further comprises a conductive member 40-1. The conductive member 40-1 is positioned between the third wiring 33-1 and the third electrode 23-1. The conductive member 40-1 electrically connects the third wiring 33-1 and the third electrode 23-1. A portion 40a of the conductive member 40-1 is positioned in a plurality of first openings 16. In the plurality of first openings 16, the portion 40a of the conductive member 40-1 is in contact with the third wiring 33-1. Another portion 40b of the conductive member 40-1 is positioned, for example, in a plurality of second openings 17. In this case, the light-emitting element 110a further comprises a first insulating film 45. The first insulating film 45 is positioned between the other portion 40b of the conductive member 40-1 and the second wiring 32-1. The first insulating film 45 insulates the conductive member 40-1 from the second wiring 32-1.

[0054] The light-emitting element 110a further comprises a second insulating film 50-1. The second insulating film 50-1 is located between the semiconductor stack 10-1 and the first wiring 31-1, between the semiconductor stack 10-1 and the second wiring 32-1, and between the semiconductor stack 10-1 and the third wiring 33-1. A portion of the second insulating film 50-1 is located between the semiconductor stack 10-1 and the second wiring 32-1 in a plurality of second apertures 17. In a top view, a portion of the second insulating film 50-1 surrounds the second wiring 32-1. Another portion of the second insulating film 50-1 is located between the semiconductor stack 10-1 and the third wiring 33-1 in a plurality of first apertures 16. In a top view, another portion of the second insulating film 50-1 surrounds the third wiring 33-1. Furthermore, another portion of the second insulating film 50-1 is positioned between the first wiring 31-1 and the third wiring 33-1, insulating the first wiring 31-1 from the third wiring 33-1. Also, yet another portion of the second insulating film 50-1 is positioned between the second wiring 32-1 and the third wiring 33-1, insulating the second wiring 32-1 from the third wiring 33-1.

[0055] The light-emitting element 110a further comprises a protective film 55. The protective film 55 is placed on the semiconductor laminate 10-1. The protective film 55 protects the semiconductor laminate 10-1.

[0056] The light-emitting device according to Modification 1 of the First Embodiment may include a support substrate having a base material and a wiring layer, similar to the light-emitting device 100. The light-emitting element 110a may be arranged on the support substrate with its third electrode 23-1 facing the support substrate. In this case, the third electrode 23-1 is electrically connected to the wiring layer of the support substrate via a conductive member.

[0057] (Current path) Referring to Figures 7A to 7C, the current paths for each light-emitting state of the light-emitting element 110a will be explained. Figure 7A is a schematic cross-sectional view showing the current path in the first light-emitting state of the light-emitting element 110a. Figure 7B is a schematic cross-sectional view showing the current path in the second light-emitting state of the light-emitting element 110a. Figure 7C is a schematic cross-sectional view showing the current path in the third light-emitting state of the light-emitting element 110a. Note that the current paths shown in Figures 7A to 7C represent typical current paths for each light-emitting state. In each light-emitting state, when current flows through the first light-emitting layer 21 of the light-emitting element 110a, the entire first light-emitting layer 21 can emit light when viewed from above. Similarly, when current flows through the second light-emitting layer 22 of the light-emitting element 110a, the entire second light-emitting layer 22 can emit light when viewed from above.

[0058] The first light-emitting state shown in Figure 7A is a state in which the first light-emitting layer 21 emits light while the second light-emitting layer 22 does not emit light. The first current path IP1 in Figure 7A represents the current path in the first light-emitting state.

[0059] In the first light-emitting state, the first electrode 21-1 functions as the anode electrode and the third electrode 23-1 functions as the cathode electrode. Current flows from the first electrode 21-1 through the first wiring 31-1, contact electrode 25, first p-type semiconductor layer 11a, first light-emitting layer 21, first n-type semiconductor layer 11c, third wiring 33-1, and conductive member 40-1 (partially 40a) to the third electrode 23-1. As a result, the first light-emitting layer 21 emits light without the second light-emitting layer 22 emitting light.

[0060] The second light-emitting state shown in Figure 7B is a state in which the first light-emitting layer 21 does not emit light, while the second light-emitting layer 22 emits light. The second current path IP2 in Figure 7B represents the current path in the second light-emitting state.

[0061] In the second light-emitting state, the third electrode 23-1 functions as the anode electrode and the second electrode 22-1 functions as the cathode electrode. Current flows from the third electrode 23-1 through the conductive member 40-1 (partially 40a), the third wiring 33-1, the first n-type semiconductor layer 11c, the intermediate layer 13-1, the second p-type semiconductor layer 12a, the second light-emitting layer 22, the second n-type semiconductor layer 12c, and the second wiring 32-1 to the second electrode 22-1. As a result, the first light-emitting layer 21 does not emit light, while the second light-emitting layer 22 emits light.

[0062] In the light-emitting device according to Modification 1 of the First Embodiment, similar to the light-emitting device 100 according to the First Embodiment, the light emission of the first light-emitting layer 21 and the light emission of the second light-emitting layer 22 of the light-emitting element 110a can be controlled individually, and the first light-emitting layer 21 and the second light-emitting layer 22 can be switched to emit light. This reduces the heat generated by the semiconductor laminate 10-1 and reduces the fluctuation of the peak wavelength of light caused by the heat generated by the semiconductor laminate 10-1.

[0063] The third light-emitting state shown in Figure 7C is a state in which both the first light-emitting layer 21 and the second light-emitting layer 22 are emitting light. The third current path IP3 in Figure 7C represents the current path in the third light-emitting state.

[0064] In the third light-emitting state, the first electrode 21-1 functions as the anode electrode and the second electrode 22-1 functions as the cathode electrode. Current flows from the first electrode 21-1 through the first wiring 31-1, contact electrode 25, first p-type semiconductor layer 11a, first light-emitting layer 21, first n-type semiconductor layer 11c, intermediate layer 13-1, second p-type semiconductor layer 12a, second light-emitting layer 22, second n-type semiconductor layer 12c, and second wiring 32-1 to the second electrode 22-1. As a result, both the first light-emitting layer 21 and the second light-emitting layer 22 emit light.

[0065] In the light-emitting device according to Modification 1 of the First Embodiment, there may or may not be a period in which the first light-emitting layer 21 and the second light-emitting layer 22 emit light simultaneously (i.e., a period in a third light-emitting state) between the period in which the first light-emitting layer 21 emits light (i.e., a period in a first light-emitting state) and the period in which the second light-emitting layer 22 emits light (i.e., a period in a second light-emitting state).

[0066] <Modification 2 of the first embodiment> (Configuration of the light-emitting element of the light-emitting device according to Modification 2 of the First Embodiment) Figure 8 is a schematic cross-sectional view showing the configuration of the light-emitting element 110b and the support substrate 18 of the light-emitting device 100b according to Modification 2 of the First Embodiment.

[0067] In the light-emitting device 100b, as shown in Figure 8, the light-emitting element 110b is placed on the support substrate 18 with the surface on which the first electrode 11, second electrode 12, and third electrode 13 of the light-emitting element 110b are arranged facing the support substrate 18. The support substrate 18 has a base material 181 and a wiring layer 182. Each of the first electrode 11, second electrode 12, and third electrode 13 of the light-emitting element 110b is electrically connected to the wiring layer 182 of the support substrate 18 via a conductive member 97. The light-emitting element 110b is an inverted version of the light-emitting element 110, and has the same configuration as the light-emitting element 110 except that among the multiple light-emitting layers 2, the light-emitting layer located closer to the support substrate 18 is the first light-emitting layer 21, and the light-emitting layer located further away from the support substrate 18 is the second light-emitting layer 22. The light-emitting element 110b may or may not have an element substrate 1. The light-emitting device 100b having the light-emitting element 110b can obtain the same effects as the light-emitting device 100.

[0068] [Second Embodiment] Next, a light-emitting device and a method for driving the light-emitting device according to the second embodiment will be described. Note that names and reference numerals identical to those used in the embodiments and modified examples already described indicate the same or identical components or parts, and detailed explanations will be omitted as appropriate.

[0069] Figure 9 is a block diagram showing an example of the overall configuration of the light-emitting device 100c according to the second embodiment. As shown in Figure 9, the light-emitting device 100c has a light-emitting element 110c and a drive unit 120c. The light-emitting device 100c further has a support substrate.

[0070] In the light-emitting element 110c, the multiple light-emitting layers 2 further include a third light-emitting layer 23 located further from the support substrate than the second light-emitting layer 22. The drive unit 120c drives the light-emitting element 110c such that the period during which the third light-emitting layer 23 emits light is shorter than the period during which the second light-emitting layer 22 emits light. During the entire period of continuous operation, the drive unit 120c emits light in the order of the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23, or in the order of the third light-emitting layer 23, the second light-emitting layer 22, and the first light-emitting layer 21. The light-emitting device 100c according to the second embodiment differs from the light-emitting device 100 according to the first embodiment in these respects.

[0071] Figure 10 is a schematic cross-sectional view showing a power supply connected to the light-emitting element 110c of the light-emitting device 100c according to the second embodiment.

[0072] In the example shown in Figure 10, the light-emitting element 110c includes an element substrate 1 and a semiconductor laminate 1000c disposed on the element substrate 1. The semiconductor laminate 1000c is arranged in the following order from the element substrate 1 side: a first n-type semiconductor layer 20, a first p-type semiconductor layer 30, a first light-emitting layer 21, a third n-type semiconductor layer 91, a second light-emitting layer 22, a third p-type semiconductor layer 92, a fourth n-type semiconductor layer 93, an insulating layer 94, a second n-type semiconductor layer 60, a third light-emitting layer 23, and a second p-type semiconductor layer 80.

[0073] The first n-type semiconductor layer 20 is tunnel-junctioned with the first p-type semiconductor layer 30. The third p-type semiconductor layer 92 and the fourth n-type semiconductor layer 93 are tunnel-junctioned. Each layer of the semiconductor laminate 1000c is made of nitride semiconductor material. The insulating layer 94 is made of, for example, AlN.

[0074] The light-emitting device 100c may have a support substrate positioned on the element substrate 1 side of the light-emitting element 110c. In this case, the third light-emitting layer 23 is located further from the support substrate than the second light-emitting layer 22. The first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 correspond to a plurality of light-emitting layers 2 arranged at different distances from the support substrate. The first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 are more easily heated in order of proximity to the support substrate. The support substrate included in the light-emitting device 100c is not limited to being positioned on the element substrate 1 side of the light-emitting element 110c, but may also be positioned on the side where the electrodes (first electrode 11 to fifth electrode 15) of the light-emitting element 110c are located.

[0075] The fifth electrode 15 is the anode electrode. The fourth electrode 14 is the cathode electrode. The first electrode 11 and the second electrode 12 are electrically connected to the first power supply 25-1, respectively. The third electrode 13 and the second electrode 12 are electrically connected to the second power supply 25-2, respectively. The fifth electrode 15 and the fourth electrode 14 are electrically connected to the third power supply 25-3, respectively. The first power supply 25-1, the second power supply 25-2, and the third power supply 25-3 are components included in the drive unit 120c.

[0076] When a voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, a current flows from the first electrode 11 through the first light-emitting layer 21 to the second electrode 12, causing the first light-emitting layer 21 to emit light. Also, when a voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, a current flows from the third electrode 13 through the second light-emitting layer 22 to the second electrode 12, causing the second light-emitting layer 22 to emit light. Furthermore, when a voltage is applied from the third power supply 25-3 to the fifth electrode 15 and the fourth electrode 14, a current flows from the fifth electrode 15 through the third light-emitting layer 23 to the fourth electrode 14, causing the third light-emitting layer 23 to emit light.

[0077] The drive unit 120c can individually switch the light emission of the first light-emitting layer 21, the second light-emitting layer 22, or the third light-emitting layer 23 by switching between states in which current flows from the first electrode 11 to the second electrode 12, in which current flows from the third electrode 13 to the second electrode 12, or in which current flows from the fifth electrode 15 to the fourth electrode 14.

[0078] For example, the drive unit 120c causes the first light-emitting layer 21 to emit light by supplying a first drive signal Dr1 to the light-emitting element 110c. The drive unit 120c also causes the second light-emitting layer 22 to emit light by supplying a second drive signal Dr2 to the light-emitting element 110c. Furthermore, the drive unit 120c causes the third light-emitting layer 23 to emit light by supplying a third drive signal Dr3 to the light-emitting element 110c. The drive unit 120c can individually switch the emission of light from the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 by adjusting the supply timing of the first drive signal Dr1, the second drive signal Dr2, and the third drive signal Dr3 to the light-emitting element 110c.

[0079] <Driving method using drive unit 120c> Figure 11 is a timing diagram showing an example of a driving method by the drive unit 120c of the light-emitting device 100c. The upper part of Figure 11 shows the change in signal intensity of the first drive signal Dr1, which causes the first light-emitting layer 21 to emit light, according to time t. The graph shown by the thick solid line corresponds to the first drive signal Dr1. When the signal intensity of the first drive signal Dr1 is High (H), a voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, causing the first light-emitting layer 21 to emit light, i.e., to light up. On the other hand, when the signal intensity of the first drive signal Dr1 is Low (L), no voltage is applied from the first power supply 25-1 to the first electrode 11 and the second electrode 12, and the first light-emitting layer 21 does not emit light, i.e., it turns off. The middle part of Figure 11 shows the change in signal intensity of the second drive signal Dr2, which drives the second light-emitting layer 22, according to time t. The graph shown with a thick solid line corresponds to the second drive signal Dr2. When the signal strength of the second drive signal Dr2 is High (H), a voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, causing the second light-emitting layer 22 to emit light, i.e., to light up. On the other hand, when the signal strength of the second drive signal Dr2 is Low (L), no voltage is applied from the second power supply 25-2 to the third electrode 13 and the second electrode 12, and the second light-emitting layer 22 does not emit light, i.e., it is turned off. The lower part of Figure 11 shows the change in signal strength of the third drive signal Dr3 that drives the third light-emitting layer 23 with respect to time t. The graph shown with a thick solid line corresponds to the third drive signal Dr3. When the signal strength of the third drive signal Dr3 is High (H), a voltage is applied from the third power supply 25-3 to the fifth electrode 15 and the fourth electrode 14, causing the third light-emitting layer 23 to emit light, i.e., to light up. On the other hand, when the signal strength of the third drive signal Dr3 is Low (L), no voltage is applied from the third power supply 25-3 to the fifth electrode 15 and the fourth electrode 14, and the third light-emitting layer 23 does not emit light, i.e., it turns off.

[0080] As shown in Figure 11, the drive unit 120c drives the light-emitting element 110c such that the period T3 during which the third light-emitting layer 23 is illuminated is shorter than the period T2 during which the second light-emitting layer 22 is illuminated. Furthermore, the drive unit 120c illuminates the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 in that order, or the third light-emitting layer 23, the second light-emitting layer 22, and the first light-emitting layer 21 in that order, for the entire duration of continuous operation. From the viewpoint of heat dissipation, it is preferable for the drive unit 120c to illuminate the first light-emitting layer 21 first.

[0081] In the light-emitting device 100c, the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 are made to emit light for a longer period of time as the distance from the element substrate 1 decreases, thereby reducing fluctuations in the peak wavelength of light emitted from the light-emitting element 110c due to heat generation. Furthermore, the light-emitting element 110c can continuously emit light without interruption due to the light from the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23. From the viewpoint of heat dissipation, it is preferable to emit light in the order of the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 rather than in the order of the third light-emitting layer 23, the second light-emitting layer 22, and the first light-emitting layer 21.

[0082] The drive unit 120c can drive the light-emitting element 110c so that one of the light-emitting layers 2 among the first light-emitting layer 21, the second light-emitting layer 22, and the third light-emitting layer 23 emits light, and so that the light-emitting layer 2 located adjacent to that light-emitting layer 2 in the stacking direction of the multiple light-emitting layers 2 does not emit light. This reduces the effect of heat generation from the adjacent light-emitting layer 2, and thus reduces fluctuations in the peak wavelength of the light emitted from the light-emitting element 110c. Here, "adjacent" means that the light-emitting layers are adjacent to each other, and parts other than the light-emitting layers located between the light-emitting layers are not considered adjacent. Also, "the stacking direction of the multiple light-emitting layers 2" refers to the Z-axis direction.

[0083] The drive unit 120c can execute the first control, the second control, and the third control in this order. The first control is a control that drives the light-emitting element 110c so that the first light-emitting layer 21 emits light, and the second light-emitting layer 22 and the third light-emitting layer 23 do not emit light. The second control is a control that drives the light-emitting element 110c so that the second light-emitting layer 22 emits light, and the first light-emitting layer 21 and the third light-emitting layer 23 do not emit light. The third control is a control that drives the light-emitting element 110c so that the third light-emitting layer 23 emits light, and the first light-emitting layer 21 and the second light-emitting layer 22 do not emit light.

[0084] Specifically, in Figure 11, the drive unit 120c performs a first control during the period from time t20 to time t21 and from time t23 to time t24. The drive unit 120c also performs a second control during the period from time t21 to time t22 and from time t24 to time t25. Furthermore, the drive unit 120c performs a third control during the period from time t22 to time t23 and from time t25 to time t26. In the second embodiment, by performing these controls, the light-emitting device 100c can emit light continuously without interruption.

[0085] In the light-emitting device 100c according to the second embodiment, the same effects as in the light-emitting device 100 according to the first embodiment can be obtained.

[0086] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0087] Multiple light-emitting layers may include four or more light-emitting layers.

[0088] The ordinal numbers, quantities, and other figures used in the description of the embodiments are all illustrative to specifically illustrate the technology of this disclosure, and this disclosure is not limited to the illustrative figures. Furthermore, the connection relationships between the components are illustrative to specifically illustrate the technology of this disclosure, and are not limited to the connection relationships that realize the functions of this disclosure.

[0089] The light-emitting device of this disclosure can reduce fluctuations in the wavelength of light emitted from the light-emitting element due to heat generation by the light-emitting element, and is therefore suitable for use in, for example, exposure equipment using ultraviolet light, printing equipment such as inkjet printers, sterilization equipment, paint curing equipment, or bonding equipment. However, the light-emitting device of this disclosure is not limited to these applications.

[0090] The aspects of this disclosure are, for example, as follows: <Item 1> A light-emitting device comprising a support substrate, a light-emitting element having a plurality of light-emitting layers disposed on the support substrate and arranged at mutually different distances from the support substrate, and a drive unit that individually switches the light emission of the plurality of light-emitting layers, wherein the plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located further from the support substrate than the first light-emitting layer, and the drive unit drives the light-emitting element such that the period during which the first light-emitting layer emits light continuously over time is longer than the period during which the second light-emitting layer emits light continuously over time. <Item 2> The drive unit is the light-emitting device described in <Item 1>, which switches the light emission of the plurality of light-emitting layers to make the light emission of the light-emitting element continuous for the entire period of continuous operation over time. <Item 3> The plurality of light-emitting layers further include a third light-emitting layer located further away from the support substrate than the second light-emitting layer, and the drive unit drives the light-emitting element such that the period during which the third light-emitting layer emits light is shorter than the period during which the second light-emitting layer emits light, and during a period of continuous driving in time, the first light-emitting layer, the second light-emitting layer and the third light-emitting layer, or the third light-emitting layer, the second light-emitting layer and the first light-emitting layer, emit light in that order, as described in <Item 1> or <Item 2>. <Clause 4> The drive unit is the light-emitting device according to <Clause 3>, which drives the light-emitting element to emit light from one of the plurality of light-emitting layers, and to prevent the light-emitting layer located next to the one light-emitting layer in the stacking direction of the plurality of light-emitting layers from emitting light. <Clause 5> The drive unit is the light-emitting device described in <Clause 3>, which sequentially executes: a first control that drives the light-emitting element to cause the first light-emitting layer to emit light and the second and third light-emitting layers to not emit light; a second control that drives the light-emitting element to cause the second light-emitting layer to emit light and the first and third light-emitting layers to not emit light; and a third control that drives the light-emitting element to cause the third light-emitting layer to emit light and the first and second light-emitting layers to not emit light. <Item 6> The drive unit is a light-emitting device according to any one of <Item 1> to <Item 5> that exclusively switches the light emission of the plurality of light-emitting layers. <Clause 7> The light-emitting element is a light-emitting device according to any one of <Clause 1> to <Clause 6> above, which is a light-emitting element that emits ultraviolet light. <Clause 8> A method for driving a light-emitting device, wherein the light-emitting device comprises a support substrate, a light-emitting element having a plurality of light-emitting layers disposed on the support substrate and arranged at mutually different distances from the support substrate, and a drive unit for individually switching the light emission of the plurality of light-emitting layers, wherein the plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located further from the support substrate than the first light-emitting layer, and the drive unit drives the light-emitting element such that the period during which the first light-emitting layer emits light is longer than the period during which the second light-emitting layer emits light. <Clause 9> The drive unit is a driving method for the light-emitting device described in <Clause 8>, which switches the light emission of the plurality of light-emitting layers to make the light emission of the light-emitting element continuous for the entire duration of continuous driving over time. <Clause 10> The plurality of light-emitting layers further include a third light-emitting layer located further away from the support substrate than the second light-emitting layer, and the drive unit drives the light-emitting element such that the period for which the third light-emitting layer emits light is shorter than the period for which the second light-emitting layer emits light, and during the period for which the light-emitting element is driven, the first light-emitting layer, the second light-emitting layer and the third light-emitting layer, or the third light-emitting layer, the second light-emitting layer and the first light-emitting layer, emit light continuously, this is the driving method for the light-emitting device according to <Clause 8> or <Clause 9>. <Clause 11> The drive unit is a driving method for the light-emitting device described in <Clause 10>, which sequentially executes: a first control that drives the light-emitting element to cause the first light-emitting layer to emit light and the second and third light-emitting layers to not emit light; a second control that drives the light-emitting element to cause the second light-emitting layer to emit light and the first and third light-emitting layers to not emit light; and a third control that drives the light-emitting element to cause the third light-emitting layer to emit light and the first and second light-emitting layers to not emit light. <Clause 12> The drive unit is a drive method for a light-emitting device according to any one of <Clause 8> to <Clause 11>, which exclusively switches the light emission of the plurality of light-emitting layers. <Clause 13> The light-emitting element is a light-emitting element that emits ultraviolet light, and the method for driving the light-emitting device described in any one of <Clause 8> to <Clause 12> is described in the above. [Explanation of Symbols]

[0091] 1 Element substrate 2. Emitting layer 11 1st electrode 12 2nd electrode 13 Third electrode 14 4th electrode 15 5th electrode 18 Support substrate 19 Joining members 20 First n-type semiconductor layer 21 First light-emitting layer 22 Second light-emitting layer 23 Third light-emitting layer 25-1 1st power supply 25-2 2nd power supply 25-3 Third power supply 30. First p-type semiconductor layer 40 superlattice layers 60 2nd n-type semiconductor layer 80 Second p-type semiconductor layer 91. Third-type semiconductor layer 92 Third p-type semiconductor layer 93. Fourth n-type semiconductor layer 94 Insulating layer 100, 100b, 100c Light-emitting devices 110, 110a, 110b, 110c light-emitting element 120, 120b, 120c drive unit 181 Base material 182 Wiring layer Dr1 First drive signal Dr2 Second drive signal Dr3 Third drive signal IP1 First current path IP2 Second current path IP3 Third Current Path T1, T2, T3 periods t10, t11, t12, t13, t14, t20, t21, t22, t23, t24, t25, t26 time

Claims

1. Support substrate and A light-emitting element having a plurality of light-emitting layers arranged on the support substrate and having different distances from the support substrate, The unit includes a drive unit that individually switches the light emission of the plurality of light-emitting layers, The plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located further from the support substrate than the first light-emitting layer. The drive unit is a light-emitting device that drives the light-emitting element such that the period during which the first light-emitting layer emits light continuously over time is longer than the period during which the second light-emitting layer emits light continuously over time.

2. The light-emitting device according to claim 1, wherein the drive unit switches the emission of light from the plurality of light-emitting layers for the entire duration of continuous operation in time, thereby causing continuous emission from the light-emitting element.

3. The plurality of light-emitting layers further include a third light-emitting layer located further away from the support substrate than the second light-emitting layer, The drive unit drives the light-emitting element such that the period during which the third light-emitting layer emits light is shorter than the period during which the second light-emitting layer emits light. The light-emitting device according to claim 1 or claim 2, wherein the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are emitted in that order, or the third light-emitting layer, the second light-emitting layer, and the first light-emitting layer are emitted in that order, during a period of continuous operation over time.

4. The aforementioned drive unit is The light-emitting device according to claim 3, wherein the light-emitting element is driven so that one of the plurality of light-emitting layers emits light, and the light-emitting layer located adjacent to the one light-emitting layer in the stacking direction of the plurality of light-emitting layers does not emit light.

5. The aforementioned drive unit is A first control that drives the light-emitting element to cause the first light-emitting layer to emit light, and the second and third light-emitting layers to not emit light; A second control that drives the light-emitting element to cause the second light-emitting layer to emit light, and the first light-emitting layer and the third light-emitting layer to not emit light, A third control that drives the light-emitting element to cause the third light-emitting layer to emit light, and the first and second light-emitting layers to not emit light, The light-emitting device according to claim 3, which performs the following steps in order.

6. The drive unit exclusively switches the emission of light from the plurality of light-emitting layers, as described in claim 1.

7. The light-emitting device according to claim 1, wherein the light-emitting element is a light-emitting element that emits ultraviolet light.

8. A method for driving a light-emitting device, wherein the light-emitting device is Support substrate and A light-emitting element having a plurality of light-emitting layers arranged on the support substrate and having different distances from the support substrate, The unit includes a drive unit that individually switches the light emission of the plurality of light-emitting layers, The plurality of light-emitting layers include a first light-emitting layer and a second light-emitting layer located further from the support substrate than the first light-emitting layer. A method for driving a light-emitting device, comprising: driving the light-emitting element with a drive unit such that the period during which the first light-emitting layer emits light is longer than the period during which the second light-emitting layer emits light.

9. The driving method for a light-emitting device according to claim 8, wherein the driving unit switches the emission of light from the plurality of light-emitting layers for the entire duration of continuous driving in time, thereby causing continuous emission of light from the light-emitting element.

10. The plurality of light-emitting layers further include a third light-emitting layer located further away from the support substrate than the second light-emitting layer, The drive unit drives the light-emitting element such that the period during which the third light-emitting layer emits light is shorter than the period during which the second light-emitting layer emits light. A method for driving a light-emitting device according to claim 8 or 9, wherein during the period for driving the light-emitting element, the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are continuously illuminated in that order, or the third light-emitting layer, the second light-emitting layer, and the first light-emitting layer are continuously illuminated in that order.

11. The aforementioned drive unit is A first control that drives the light-emitting element to cause the first light-emitting layer to emit light, and the second and third light-emitting layers to not emit light; A second control that drives the light-emitting element to cause the second light-emitting layer to emit light, and the first light-emitting layer and the third light-emitting layer to not emit light, A third control that drives the light-emitting element to cause the third light-emitting layer to emit light, and the first and second light-emitting layers to not emit light, A method for driving a light-emitting device according to claim 10, wherein the following steps are performed in order.

12. The driving unit exclusively switches the emission of light from the plurality of light-emitting layers, as described in claim 11.

13. The method for driving a light-emitting device according to claim 8 or claim 9, wherein the light-emitting element is a light-emitting element that emits ultraviolet light.

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