Light emitting device, image forming apparatus, imaging apparatus, display, electronic apparatus, illumination device, movable body, and wearable device

Abstract

To provide a light emitting device having an advantageous configuration to prevent a reduction in light emission quality, and an image forming apparatus, an imaging apparatus, a display, an electronic apparatus, an illumination device, a movable body, and a wearable device to which the light emitting device is applied.SOLUTION: In a light emitting device in which a plurality of pixels are arranged in matrix on a semiconductor substrate 400, each of the plurality of pixels comprises a light emitting element, a drive transistor 202 that supplies current to the light emitting element, and a switching transistor 204 that controls the light emitting element. A gate electrode 307 of the switching transistor is provided on at least two surfaces of four surfaces surrounding a cross section of an area 404 to be a channel.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device, for example, a light-emitting device having an organic light-emitting element, and to an image forming apparatus, an imaging apparatus, a display device, an electronic device, a lighting apparatus, a mobile object, and a wearable device to which the light-emitting device is applied. [Background technology]

[0002] For example, an organic light-emitting element is used as the light-emitting element. In Patent Document 1, a switching transistor is provided between two terminals of the light-emitting element, an anode and a cathode, to control whether the light-emitting element emits light or not. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-85287 Summary of the Invention [Problem to be solved by the invention]

[0004] When the source-drain voltage or well voltage fluctuates, the on / off of the switching transistor becomes incomplete, which can lead to incomplete control of the light-emitting element's light emission and non-light-emission. This can cause variations in the amount of light emitted, resulting in a deterioration in light emission quality. The present invention aims to provide a light-emitting device with a configuration that is advantageous for suppressing the deterioration in light emission quality. [Means for solving the problem]

[0005] A light-emitting device according to one aspect of the present invention is a light-emitting device in which a plurality of pixels are arranged in a matrix on a semiconductor substrate, and each of the plurality of pixels comprises a light-emitting element, a drive transistor that supplies current to the light-emitting element, and a switching transistor that controls the light-emitting element, and the gate electrode of the switching transistor is provided on at least two of the four sides surrounding the cross section of a region that becomes a channel. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a light emitting device having a configuration that is advantageous in suppressing deterioration in light emission quality. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram of a light-emitting device. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a pixel. [Figure 3] FIG. 2 is a plan view of a pixel according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a pixel according to the first embodiment. [Figure 5] FIG. 2 is a diagram for explaining the creation of a circuit according to the first embodiment. [Figure 6] FIG. 2 is a diagram for explaining the creation of a circuit according to the first embodiment. [Figure 7] FIG. 2 is a diagram for explaining the creation of a circuit according to the first embodiment. [Figure 8] FIG. 10 is a plan view of a pixel according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a pixel according to a second embodiment. [Figure 10] FIG. 10 is a diagram for explaining the creation of pixels according to the second embodiment. [Figure 11] FIG. 10 is a diagram for explaining the creation of pixels according to the second embodiment. [Figure 12] FIG. 10 is a diagram for explaining the creation of pixels according to the second embodiment. [Figure 13] 1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 14] 1 is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention. [Figure 15] 1A is a schematic diagram showing an example of an imaging device according to an embodiment of the present invention; FIG. 1B is a schematic diagram showing an example of an electronic device according to an embodiment of the present invention; [Figure 16] 1A is a schematic diagram showing an example of a display device according to an embodiment of the present invention; FIG. 1B is a schematic diagram showing an example of a foldable display device; [Figure 17]1A is a schematic diagram showing an example of a lighting device according to an embodiment of the present invention; FIG. 1B is a schematic diagram showing an example of a vehicle having a vehicle lamp according to an embodiment of the present invention; [Figure 18] 1A and 1B are schematic diagrams showing an example of a wearable device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0009] (Embodiment 1) Fig. 1 is a block diagram of a light-emitting device 101 according to the present embodiment. This embodiment will be described here using an active matrix display device as an example. As shown in Fig. 1, the light-emitting device 101 has a pixel array section 103 and a drive section arranged around the pixel array section 103. The pixel array section 103 has a plurality of pixels 102 arranged two-dimensionally in a matrix, and each pixel 102 has a light-emitting element 201 shown in Fig. 2 and a circuit including a transistor arranged around the light-emitting element.

[0010] The light-emitting element 201 may be a current-driven electro-optical element whose luminance changes according to the value of the current flowing through the device, such as an organic light-emitting diode (OLED). The following describes a case where the electro-optical element is an OLED. The light-emitting element 201 has an organic layer including a light-emitting layer between an anode and a cathode. In addition to the light-emitting layer, the organic layer may have at least one of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

[0011] The light emitting device 101 includes a driver that drives each pixel. The driver includes a vertical scanning circuit 104 and a signal output circuit 105. The driver is controlled by a controller to operate the light emitting device as a display device. In FIG. 1, in a pixel array section 103 in which pixels 102 are arranged in a matrix, a first scanning line 106 and a second scanning line 107 are arranged for each pixel row along the row direction. Furthermore, a signal line 108 is arranged for each pixel column along the column direction.

[0012] The first scanning line 106 and the second scanning line 107 are connected to output terminals of corresponding rows in the vertical scanning circuit 104. Furthermore, the signal line 108 is connected to output terminals of corresponding columns in the signal output circuit 105.

[0013] The vertical scanning circuit 104 can be configured with a shift register or the like that shifts a start pulse in sequence in synchronization with a clock pulse. The vertical scanning circuit 104 supplies a write control signal to a first scanning line 106 when writing a video signal to each pixel 102 of the pixel array unit 103. In addition, the vertical scanning circuit 104 supplies a reset signal to a second scanning line 107 during a non-light emitting period.

[0014] The signal output circuit 105 outputs a signal voltage (luminance signal) according to luminance information supplied from the outside. The output signal voltage is supplied to the corresponding pixel 102 via a signal line 108.

[0015] In a pixel where a write signal from the first scanning line 106 is activated, the light emitting element 201 can emit light in response to a signal voltage supplied from the signal line 108. In a pixel where a reset signal from the second scanning line is supplied, the light emitting element can be controlled to not emit light. The vertical scanning circuit 104 can output a write control signal and a reset signal sequentially for each row.

[0016] The driving unit does not need to be arranged on the same substrate as the pixel array unit 103. The pixel array unit 103 may be arranged on a first substrate, and at least a part of the driving unit may be arranged on a second substrate, with the first substrate and the second substrate being stacked.

[0017] In this specification, when the light emitting device 101 is a display device capable of black and white display, one pixel serving as a unit for forming a black and white image corresponds to the pixel 102. On the other hand, when the light emitting device 101 is a display device capable of color display, one pixel serving as a unit for forming a color image may be composed of a plurality of sub-pixels, and the sub-pixels may correspond to the pixel 102. More specifically, in a display device capable of color display, one pixel may be composed of three sub-pixels: a sub-pixel that emits red (R) light, a sub-pixel that emits green (G) light, and a sub-pixel that emits blue (B) light.

[0018] A pixel is not limited to a combination of sub-pixels of the three primary colors of RGB. That is, it is also possible to configure a pixel by adding sub-pixels of one or more colors to the sub-pixels of the three primary colors. More specifically, it is also possible to configure a pixel by adding a sub-pixel that emits white (W) light to improve brightness, or by adding at least one sub-pixel that emits complementary color light to expand the color reproduction range.

[0019] 2 is a circuit diagram showing an example of the configuration of a pixel 102 included in the light-emitting device 101 of FIG. 2. As shown in FIG. 2, the pixel 102 may include an OLED element that functions as a light-emitting element 201, and a drive circuit that drives the light-emitting element 201. The pixel 102 includes the light-emitting element 201, a drive transistor 202, and a write transistor 203. One of the drain or source of the drive transistor 202 is connected to a power supply potential Vdd, and the other is connected to one of the main terminals of the light-emitting element 201.

[0020] In this example, the driving transistor 202 is connected to the anode electrode of the light emitting element 201. The pixel 102 further includes a switching transistor 204 and a first capacitor element 205.

[0021] In this embodiment, one of the drain or source of the switching transistor 204 is connected to the point where the drive transistor 202 and the light emitting element 201 are connected. In this example, the other of the drain or source of the switching transistor 204 is connected to a reference power supply potential Vss. In this embodiment, the power supply potential Vdd is higher than the power supply potential Vss.

[0022] Here, the total number of transistors and capacitors and the combination of the conductivity types of the transistors are merely examples and are not limited to this configuration. In addition, the total number of transistors and capacitors may be the same for multiple pixels, or the light-emitting device may include pixels with different total numbers of transistors and capacitors.

[0023] When the light-emitting device is used as a display device capable of displaying colors, the configuration may be changed depending on the color. The capacitance value of the first capacitance element 205 in the subpixel that emits blue may be larger than the capacitance value of the first capacitance element 205 in the subpixel that emits green. In the following description, when a transistor is said to be connected between element A and element B, one terminal (source region or drain region) of the transistor is connected to element A, and the other terminal of the transistor is connected to element B.

[0024] A description will be given of the circuit operation of the pixel 102. In this embodiment, one end of a current path including the light emitting element 201, the driving transistor 202, and the switching transistor 204 is connected to the power supply potential Vss, and the other end is connected to the power supply potential Vdd.

[0025] More specifically, one of the main terminals of the light-emitting element 201 (cathode in the example of FIG. 2) and one of the drain or source of the switching transistor 204 (drain region in the example of FIG. 2) are connected to the power supply potential Vss. The other of the main terminals of the light-emitting element 201 (anode) and the other of the drain or source of the switching transistor 204 (source region in FIG. 2) are connected to the power supply potential Vdd via the drive transistor 202.

[0026] One of the drain or source of the write transistor 203 (the drain region in the example of FIG. 2) is connected to the gate of the drive transistor 202, and the other of the drain or source of the write transistor 203 (the source region in FIG. 2) is connected to the signal line 108. The gate of the write transistor 203 is connected to the first scan line 106.

[0027] One of the drain or source of the switching transistor 204 (the drain region in the example of FIG. 2 ) is connected to the power supply potential Vss 207. The gate of the switching transistor 204 is connected to the second scan line 107. Since the cathode electrode of the light-emitting element 201 is also connected to the power supply voltage Vss, when the switching transistor 204 is controlled to be conductive, the two main terminals (anode and cathode) of the light-emitting element 201 are short-circuited. In order to control the light-emitting element 201 to not emit light, the anode of the light-emitting element 201 is connected to the power supply potential Vss 207 by turning on the switching transistor 204 during the non-light-emitting period, thereby putting the light-emitting element 201 into a non-light-emitting state. The other terminal of the drain or source of the switching transistor may be connected to a predetermined potential (preferably a potential more negative than Vss when Vdd is a positive potential) that can make the light-emitting element 201 not emit light when the switching transistor is controlled to be conductive.

[0028] The first capacitance element 205 is connected between a node to which the gate of the driving transistor 202 is connected and a node to which either the drain or the source (the source in the example of FIG. 2) is connected. The first capacitance element 205 can be selected from a parasitic capacitance, an MIM (Metal-Insulator-Metal) structure, a MOS (Metal-Oxide-Semiconductor) structure, etc.

[0029] The driving transistor 202 supplies a current from the power supply potential Vdd 206 to the light emitting element 201 to cause it to emit light. More specifically, the driving transistor 202 supplies a current according to the signal voltage of the signal line 108 to the light emitting element 201. This causes the light emitting element 201 to emit light by current driving.

[0030] A write control signal is supplied from the vertical scanning circuit 104 to the gate of the write transistor 203 through the first scanning line 106. The write transistor 203 is controlled between a conductive state and a non-conductive state in response to the write control signal. The write transistor 203 can transmit a luminance signal to the light-emitting element 201. By turning the write transistor 203 into a conductive state, the write transistor 203 samples a signal voltage of a luminance signal corresponding to luminance information supplied from the signal output circuit 105 via the signal line 108 and writes the signal voltage to the pixel 102. This written signal voltage is applied to the gate of the drive transistor 202.

[0031] In this embodiment, the explanation will continue with an example in which an OLED element is used as the light-emitting element 201. When the light-emitting element 201 emits light, the amount of current flowing through the drive transistor 202 changes in accordance with the signal voltage applied to the gate of the drive transistor 202 from the signal line 108 via the write transistor 203. This charges the capacitance between the anode and cathode of the light-emitting element 201 to a predetermined potential, and a current corresponding to this potential difference flows. This causes the light-emitting element 201 to emit light at a predetermined brightness.

[0032] 3 is a schematic plan view of a portion of a pixel array 103 in which a plurality of pixels 102 are arranged. Here, P-channel MOSFETs are used as transistors, but N-channel MOSFETs may also be used. Furthermore, a configuration in which P-channel and N-channel MOSFETs are mixed may also be used.

[0033] The driving transistor 202 is composed of a gate electrode 301, a P-type diffusion region 302 that functions as one of the source region and the drain region, and a P-type diffusion region 303 that functions as the other of the source region and the drain region. In Fig. 3, the gate electrode 301 is connected to one terminal of the first capacitance element 205 in Fig. 2, and the diffusion region 303 is connected to the other terminal of the first capacitance element 205. Furthermore, the diffusion region 303 is connected to a power supply potential Vdd 206. The diffusion region 302 is connected to the anode of the light-emitting element 201.

[0034] The write transistor 203 is composed of a gate electrode 304, a P-type diffusion region 305 that functions as either the source region or the drain region, and a P-type diffusion region 306 that functions as the other of the source region or the drain region. In the example of FIG. 3, the diffusion region 305 functions as the drain region, and the diffusion region 306 functions as the source region. The diffusion region 305 is connected to the gate electrode 301 of the drive transistor 202 and holds a signal voltage. When the write transistor 203 is in the OFF state, the potential of the diffusion region 305 that functions as the drain region of the write transistor 203 and the potential of the gate electrode of the drive transistor 202 are floating.

[0035] The potential of the gate electrode 301 of the driving transistor 202 is equal to the potential of the diffusion region 305 that functions as the drain region of the writing transistor 203. The potential of the gate electrode 301 of the driving transistor 202 determines the drain current of the driving transistor 202 and the luminance of the light-emitting element 201. The diffusion region 306 is connected to the signal line 108, and the gate electrode 304 is connected to the first scanning line 106.

[0036] The switching transistor 204 is composed of a gate electrode 307, a P-type diffusion region 302 that functions as either a source region or a drain region, and a P-type diffusion region 308 that functions as the other of the source region or the drain region. The gate electrode 307 is connected to the second scan line 107. The diffusion region 302 is shared by the driving transistor 202 and the switching transistor 204. However, this is not limited to this, and the diffusion regions of the driving transistor 202 and the switching transistor 204 may be independent from each other. The diffusion region 308 is connected to a power supply potential Vss 207. In addition, the diffusion region closest to the diffusion region 308 in a plan view is the diffusion region 305.

[0037] Each source region and drain region is connected to a contact plug 309. Each source region and drain region may have an LDD structure, which is expected to suppress leakage current.

[0038] The region to which the contact plug 309 is connected may have a higher impurity concentration than the surrounding source and drain regions. In the source and drain regions, the impurity concentration of the portion to which the contact plug is connected may be higher than the impurity concentration of the portion that forms the interface with the well 402. Furthermore, forming a silicide containing W, Co, or the like in the region to which the contact plug 309 is connected can reduce electrical resistance.

[0039] The structures of the switching transistor 204 and the drive transistor 202 will be described with reference to Figures 4(a) and 4(b). Figure 4(a) is a cross-sectional view taken along line X1-X1' shown in Figure 3, and is a diagram illustrating the cross-sectional structure of the switching transistor 204. Regarding Figure 4 in relation to Figure 3, the cut surfaces along lines X1-X1' and X2-X2' are cross sections perpendicular to the current flowing between the drain and source.

[0040] The substrate 400 is a semiconductor substrate, and in this embodiment, a single crystal silicon substrate will be described as an example. An N-type well 402 is formed on a P-type substrate 401. An element isolation portion 403 is formed in a part of the N-type well 402. The element isolation portion 403 is formed by STI (Shallow Trench Isolation) or LOCOS (Local Oxidation of Silicon), and is made of an insulator such as silicon oxide. A channel region 404 is a part of the N-type well 402, and is arranged between the multiple element isolation portions 403.

[0041] A gate electrode 307 is disposed above the channel region 404. In this example, the gate electrode 307 is made of polysilicon, but it may be made of other conductive materials. An interlayer film 601 is disposed above the gate electrode 307. The interlayer film 601 is made of an insulator such as silicon oxide.

[0042] A gate insulating film 405 is disposed between the gate electrode 307 and the channel region 404. Silicon oxide can be used for the gate insulating film 405. To ensure a high breakdown voltage, the film thickness should be selected according to the voltage used in the circuit. In the case of the switching transistor 204, it is necessary to use a relatively high voltage to drive the light emitting element 201. A specific example is about 5 to 20 V. When used at such a voltage, the breakdown voltage can be ensured by setting the film thickness of the gate insulating film 405 to about 10 to 40 nm. For the same reason, the gate length must also be a distance that ensures a high breakdown voltage, and a specific example is 0.5 um or more.

[0043] A feature of this embodiment is that the gate electrode 307 has a vertical gate electrode structure by having a portion buried in the substrate 400 as well as an upper portion thereof. The gate electrode 307 is composed of a portion 307a on the substrate 400 and a portion 307b buried in a groove in the substrate 400, and surrounds the channel region 404 from above the substrate 400 as well as from both sides. The shape of the gate electrode 307 can be an inverted U-shape or a U-shape with respect to the bottom surface of the substrate 400 when viewed in a cross section perpendicular to the direction of current flow. With respect to the channel region surrounded by the gate electrode 307, an element isolation portion 403 can be positioned adjacent to the gate electrode 307 on the outer side of the gate electrode 307.

[0044] With this trench gate (groove) structure, in which the gate electrode is located in the groove of the substrate, the electric field of the gate electrode 307 can affect the channel region 404 from more surfaces than with a conventional gate electrode with a planar structure. This makes it possible to improve the controllability of ON / OFF by forming a channel between the source and drain using gate voltage. Here, improved controllability refers to an increase in current when ON and a reduction in leakage current when OFF.

[0045] In the circuit configuration of the pixel 102, the switching transistor 204 has the role of controlling whether the light-emitting element 201 emits light or not. Therefore, it is required to reliably turn on / off the transistor even in situations where the source-drain voltage and well voltage fluctuate. If the switching transistor 204 is incompletely turned on / off, the control of whether the light-emitting element 201 emits light or not will be incomplete, and the amount of light emitted by the light-emitting element 201 will vary, which may lead to a deterioration in image quality. If the switching transistor 204 is structured as in this embodiment, it will be possible to improve the controllability of the on / off state using the gate voltage, and improvement in image quality can be expected.

[0046] In this embodiment, the gate electrode 307b is illustrated as being embedded in a part of the element isolation portion 403. However, the gate electrode may be embedded in a part of the channel region 404, or may be embedded across a part of the element isolation portion 403 and a part of the channel region 404.

[0047] Furthermore, in this embodiment, when a channel 404 through which a current flows between the source and drain is viewed in a cross section perpendicular to the direction of current flow, the gate electrodes 307a and 307b are arranged on three of the four sides surrounding the cross section. Specifically, the gate electrodes are arranged on a total of three sides along the direction of current flow: one side on the surface side of the substrate and two sides on both sides of the region that will become the channel. However, the gate electrodes may also be provided on two sides: one on the surface side of the substrate and one on one side of the region surrounding the channel. Alternatively, the gate electrode in the groove may be configured to be embedded in the center of the channel 404.

[0048] By making the depth of the gate electrode 307b shallower than the depth of the element isolation portion 403, it becomes easier to process a trench for embedding the gate electrode 307b when fabricating a transistor. Also, it is preferable that the depth of the gate electrode 307b is more than twice the film thickness of the gate insulating film 405. In this case, the gate electrode 307b faces the side surface of the channel region 404, and it is expected that the electric field from the gate electrode 307b will more effectively affect the side surface of the channel region 404. This makes it possible to further improve the controllability of ON / OFF (channel formation) by the gate voltage.

[0049] Figure 4(b) is a cross-sectional view of the driving transistor 202 taken along the line X2-X2' in Figure 3. The difference from Figure 4(a) is that the gate electrode 301 is disposed only on the top of the substrate 401 and is a planar structure that is not embedded in the substrate 401.

[0050] When the light emitting element 201 emits light, the amount of current flowing through the drive transistor 202 changes depending on the signal voltage applied to the gate of the drive transistor 202 from the signal line 108 via the write transistor 203. Therefore, if the characteristics of the drive transistor 202 vary from pixel to pixel, the image may become grainy, degrading the image quality.

[0051] 4(a) is applied to the driving transistor 202, a groove for embedding the gate electrode 301 needs to be formed in the element isolation part 403, which may cause processing variations in the shape of the gate electrode 301. The processing variations may ultimately become a factor in the characteristics variations of the driving transistor 202.

[0052] On the other hand, with a planar structure as shown in Figure 4(b), it is easy to suppress variations in characteristics caused by variations in the shape of the gate electrode 301, making it possible to minimize deterioration in image quality. If variations in the characteristics of the drive transistor 202 are acceptable, a transistor with a trench gate structure as shown in Figure 4(a) may be used. The write transistor 203 may have either a trench gate structure or a planar structure, and can be selected appropriately depending on the circuit design, pixel circuit layout, etc.

[0053] 5 to 7 are diagrams illustrating the process of fabricating each transistor while comparing the cross-sectional structures of the switching transistor 204 and the driving transistor 202. The method of fabricating the transistor of this embodiment will be described below with reference to FIGS. 5 to 7. The upper diagrams of FIGS. 5 to 7 indicated by 204 are cross-sectional views of the switching transistor 204 shown in FIG. 3 taken along the X1-X1' line. The lower diagrams of FIGS. 5 to 7 indicated by 202 are cross-sectional views of the driving transistor 202 taken along the X2-X2' line.

[0054] 5(a): An element isolation region 403 is formed in a substrate 400 consisting of a P-type substrate 401 and an N-type well 402. The element isolation region 403 can be made of silicon oxide or the like. The element isolation region 403 can have a structure such as STI or LOCOS. The region of the N-type well 402 sandwiched between the element isolation regions 403 becomes a channel region 404.

[0055] FIG. 5(b): Next, a resist mask 501 is formed on the substrate 400 of the switching transistor 204, and a portion of the element isolation portion 403 is removed by dry etching or the like to form a groove 502. In this embodiment, the groove 502 is formed between the N-type well 402, which becomes the channel region 404, and the element isolation portion 403. The groove 502 is the location where the gate electrode 307 will be formed. Here, the drive transistor 202 has a planar structure, so no groove is formed. Since the gate electrode of the switching transistor 204 has a trench gate structure, the groove 502 is formed only in the region of the switching transistor 204. The groove 502 may also be formed by wet etching. The width of the groove 502 is approximately 100 to 400 nm.

[0056] After the trench 502 is formed, the resist mask 501 is removed. Thereafter, sacrificial oxidation may be performed to remove layers damaged by etching the trench 502. Also, isotropic etching may be performed to round the bottom shape of the trench 502 and ensure embedding of the polysilicon film. Channel doping may be performed by ion implantation or the like to adjust the threshold value of the transistor.

[0057] FIG. 6(a): A gate insulating film 405 is formed on a substrate 400. The gate insulating film 405 can be made of silicon oxide. A silicon oxide film can be formed by thermal oxidation, ISSG (In situ steam generation) oxidation, or the like. The gate insulating film 405 can be formed on a portion including the sidewall of the region that will become the channel of the trench 502 and on the surface of the region that will become the channel of the substrate 400. The thickness of the gate insulating film 405 is about 10 to 40 nm, and the thickness can be selected appropriately depending on the voltage applied to the transistor.

[0058] FIG. 6(b): An electrode made of a polysilicon film 503 is formed on the surface of the substrate 400. At this time, an electrode is also formed in the trench 502 of the switching transistor 204. The material of the electrode is not limited to polysilicon. The film thickness of the polysilicon film 503 is approximately 100 to 400 nm. If the width of the aforementioned trench 502 is set to be no more than twice the film thickness of the polysilicon film 503, the polysilicon film 503 can be embedded well into the trench 502. Furthermore, if the width of the trench 502 is set to be no more than one time the film thickness of the polysilicon film 503, it is possible to suppress a step in the polysilicon film 503 that occurs above the trench 502.

[0059] FIG. 7(a): Next, a resist mask 504 is formed on the polysilicon film 503, and the gate electrodes 301 and 307 are formed by dry etching or the like.

[0060] 7(b): Next, the resist mask 504 is removed, and then an interlayer film 601 is formed. Before forming the interlayer film 601, it is possible to form a source region and a drain region by ion implantation or the like, or to appropriately form a silicide containing W, Co, or the like in the region to which the contact plug 309 is connected.

[0061] In this manner, a gate electrode having an inverted U-shaped or U-shaped electrode is formed on the X1-X1' cross section of the switching transistor 204. The channel region 404 can be formed inside the gate electrode having an inverted U-shaped or U-shaped cross section. A planar gate electrode is formed in the driving transistor 202. According to the above-described manufacturing method, it is possible to simultaneously form transistors having gate electrodes with a trench gate structure and a planar structure on the same substrate.

[0062] (Embodiment 2) A light emitting device 101 according to this embodiment will be described with reference to FIGS. The schematic configuration of the display device and the circuit configuration of the pixels 102 shown in Figures 1 and 2 of Embodiment 1 are the same as those of Embodiment 1. Figure 8 is a schematic plan view of a plurality of pixels 102 in this embodiment. Figure 9(a) is a cross-sectional view taken along line X3-X3' in Figure 8, and is a diagram illustrating the cross-sectional structure of the switching transistor 204. Figure 9(b) is a cross-sectional view taken along line X4-X4' in Figure 8, and is a diagram illustrating the cross-sectional structure of the driving transistor 202.

[0063] The difference from the first embodiment is that the switching transistor 204 has a fin-gate structure that protrudes from the base of the substrate 400. The switching transistor 204 is formed on the substrate 400, and most of the element isolation portion 403 around the channel 404 has been removed. The periphery of the channel 404 is covered with a gate insulating film 405, and a gate electrode 307 is disposed outside of the gate insulating film 405 so as to surround the channel 404. The structure is such that the gap between adjacent switching transistors 204 is filled with an interlayer film 601.

[0064] With the switching transistor 204 having such a structure, most of the channel 404 except for the lower part can be surrounded by the gate electrode 307, and it can be expected that the electric field of the gate electrode 307 will effectively act on the channel 404. This makes it possible to improve the controllability of ON / OFF (channel formation) by the gate voltage, and it can be expected that the image quality will be improved.

[0065] The driving transistor 202 has a planar structure, as in the first embodiment. When a fin-gate structure is used as the gate electrode of the driving transistor 202, it is necessary to form a void around the channel 404 for processing. If variations in the shape occur during processing of the void, this may result in variations in the characteristics of the driving transistor 202. A planar structure such as that shown in FIG. 9(b) can suppress variations in the shape caused by the formation of the void, thereby minimizing degradation in image quality. If variations in the characteristics are acceptable, the driving transistor 202 may have a fin-gate structure such as that shown in FIG. 9(a). The writing transistor 203 may have either a fin-gate structure or a planar structure, and can be selected appropriately depending on the circuit design, pixel circuit layout, etc.

[0066] A method for fabricating the transistor of this example will be described with reference to Figures 10 to 12. Figures 10 to 12 are cross-sectional views taken along lines X3-X3' and X4-X4' shown in Figure 8, and illustrate the cross-sectional structures of the switching transistor 204 and the driving transistor 202. The diagram indicated by 204 in the upper part of Figure 10(a) is a cross-sectional view of the switching transistor 204. The diagram indicated by 202 in the lower part of Figure 10(a) is a cross-sectional view of the driving transistor 202.

[0067] 10(a): An element isolation region 403 is formed in a substrate 400 consisting of a P-type substrate 401 and an N-type well 402. The element isolation region 403 can be made of silicon oxide or the like. The element isolation region 403 can have a structure such as STI or LOCOS. The region of the N-type well 402 sandwiched between the element isolation regions 403 becomes a channel region 404. Up to this point, the process is the same as in embodiment 1.

[0068] 10(b): Next, a resist mask 501 is formed on the substrate 400, and a portion of the element isolation portion 403 is removed by dry etching or the like to form a void 801. Here, the drive transistor 202 has a planar structure and the switching transistor 204 has a fin-gate structure, so the void 801 is formed only in the region of the switching transistor 204. A portion of the element isolation portion 403 is left below the void 801. The void 801 may also be formed by wet etching.

[0069] After forming the void 801, the resist mask 501 is removed. Thereafter, sacrificial oxidation may be performed to remove layers damaged by etching the void 801. Also, isotropic etching may be performed to round the bottom shape of the void 801 and ensure embedding of the polysilicon film. Channel doping may be performed by ion implantation or the like to adjust the threshold value of the transistor.

[0070] FIG. 11(a): Next, a gate insulating film 405 is formed on the substrate 400. The gate insulating film 405 is preferably made of silicon oxide. A silicon oxide film can be formed by thermal oxidation, ISSG oxidation, or the like. Through the above steps, the gate insulating film 405 is formed on the surface of the substrate 400, including the void 801. The thickness of the gate insulating film 405 is about 10 to 40 nm, and can be selected appropriately depending on the voltage applied to the transistor.

[0071] 11(b): A polysilicon film 503 is formed on the surface of the substrate 400. The thickness of the polysilicon film 503 is approximately 100 to 400 nm. The thickness of the polysilicon film 503 is preferably ¼ or less of the spacing between the channels 404 of the switching transistors 204. With this structure, the voids 801 are not filled with the polysilicon film 503, and the formation of the gate electrodes 301 and 307, which will be described later, can be easily performed.

[0072] FIG. 12(a): Next, a resist mask 504 is formed on the polysilicon film 503, and the gate electrodes 301 and 307 are formed by dry etching or the like.

[0073] 12(b): After removing the resist mask 504, an interlayer film 601 is formed. Before forming the interlayer film 601, it is possible to form a source region and a drain region by ion implantation or the like, or to appropriately form a silicide containing W, Co, or the like in the region to which the contact plug 309 is connected.

[0074] This manufacturing method makes it possible to simultaneously form transistors having gate electrodes of both fin-gate and planar structures on the same substrate.

[0075] (Example of application of light emitting devices) An example in which the light-emitting devices according to the first and second embodiments are applied to equipment will be described below. It is preferable to use organic light-emitting elements as the light-emitting elements. FIG. 13 shows an image forming apparatus according to this embodiment. FIG. 13(a) is a schematic diagram of an image forming apparatus 926 according to this embodiment. The image forming apparatus has a photoconductor 927, an exposure light source 928, a developing unit 931, a charging unit 930, a transfer unit 932, a conveying unit 933, and a fixing unit 935.

[0076] Light 929 is emitted from an exposure light source 928, and an electrostatic latent image is formed on the surface of a photoconductor 927. This exposure light source has the light-emitting device according to embodiments 1 and 2. A developing unit 931 has a developing material such as toner, and applies the developer to the exposed photoconductor 927. A charging unit 930 charges the photoconductor 927. A transfer unit 932 transfers the developed image to a recording medium 934. A transport unit 933 transports the recording medium 934. The recording medium 934 is, for example, paper. A fixing unit 935 fixes the image formed on the recording medium.

[0077] 13(b) and 13(c) are schematic diagrams showing an exposure light source 928 in which multiple light-emitting units 936 are arranged on a long substrate. Arrow 937 indicates a direction parallel to the axis of the photoconductor, representing the row direction in which the light-emitting elements are arranged. Organic light-emitting elements can be used as the light-emitting elements. This row direction is the same as the axis direction about which the photoconductor 927 rotates. This direction can also be called the long axis direction of the photoconductor.

[0078] Figure 13(b) shows a configuration in which the light-emitting units are arranged along the longitudinal axis of the photoconductor. Figure 13(c) shows a different configuration from Figure 13(b), in which the light-emitting units are arranged alternately in the column direction in each of the first and second columns. The first and second columns are arranged at different positions in the row direction.

[0079] In the light-emitting section of Fig. 13(c), the first column has multiple light-emitting sections arranged at intervals. The second column has light-emitting sections at positions corresponding to the intervals between the light-emitting sections in the first column. That is, multiple light-emitting sections are also arranged at intervals in the row direction. The arrangement of Fig. 13(c) can also be described as, for example, a grid arrangement, a houndstooth arrangement, or a checkerboard pattern.

[0080] 14 is a schematic diagram illustrating an example of a display device that can use the light-emitting devices according to the first and second embodiments. The display device 1000 may have a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected by flexible printed circuits FPCs 1002 and 1004. A transistor is disposed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, and may be provided in a different position even if the display device is a portable device.

[0081] The display device according to this embodiment may have color filters having red, green, and blue colors, which may be arranged in a delta arrangement.

[0082] The display device according to the present embodiment may be used as a display unit of a mobile terminal. In this case, the display device may have both a display function and an operation function. Examples of the mobile terminal include a mobile phone such as a smartphone, a tablet, and a head-mounted display.

[0083] The display device according to this embodiment may be used as a display unit of an imaging device having an optical unit with a plurality of lenses and an imaging element that receives light that has passed through the optical unit. The imaging device may have a display unit that displays information acquired by the imaging element. The display unit may be a display unit exposed to the outside of the imaging device or a display unit disposed within a viewfinder. The imaging device may be a digital camera or a digital video camera.

[0084] 15(a) is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may have a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may have a display device using the light-emitting device according to the first or second embodiment. In this case, the display device may display not only an image to be captured, but also environmental information, imaging instructions, and the like. The environmental information may include the intensity of external light, the direction of external light, the speed at which the subject is moving, the possibility that the subject will be blocked by an obstruction, and the like.

[0085] Since the optimum timing for capturing an image is very short, it is better to display information as quickly as possible. Therefore, it is advisable to use organic light-emitting elements as the light-emitting elements, as organic light-emitting elements have a fast response speed. Display devices using organic light-emitting elements are more suitable than liquid crystal display devices, which require high display speed.

[0086] The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses, which form an image on an imaging element housed in a housing 1104. The focus of the multiple lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically. The imaging device may also be called a photoelectric conversion device. Instead of sequentially capturing images, the photoelectric conversion device can include an imaging method that detects the difference from the previous image, or a method of cutting out an image from a constantly recorded image, etc.

[0087] FIG. 15(b) is a schematic diagram showing an example of an electronic device according to this embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint to unlock the device, etc. An electronic device having a communication unit can also be called a communication device. The electronic device may further have a camera function by including a lens and an image sensor. An image captured by the camera function is displayed on the display unit. Examples of the electronic device include a smartphone and a laptop computer.

[0088] 16(a) and 16(b) are schematic diagrams showing an example of a display device using the light-emitting device according to the first and second embodiments. FIG. 16(a) shows a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. When the light-emitting device according to the first and second embodiments is used in the display unit 1302, degradation of the displayed image can be suppressed.

[0089] It has a frame 1301 and a base 1303 that supports a display unit 1302. The base 1303 is not limited to the form shown in Fig. 11(a). The bottom side of the frame 1301 may also serve as the base.

[0090] The frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

[0091] FIG. 16(b) is a schematic diagram illustrating another example of a display device. The display device 1310 in FIG. 16(b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may include the light-emitting devices according to the first and second embodiments. The first display unit 1311 and the second display unit 1312 may be a single, seamless display unit. The first display unit 1311 and the second display unit 1312 can be separated by the bending point. The first display unit 1311 and the second display unit 1312 may display different images, or the first and second display units may display a single image.

[0092] FIG. 17(a) is a schematic diagram illustrating an example of an illumination device using the light-emitting device according to the first or second embodiment. The illumination device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion unit 1405. The light source may include the light-emitting device according to the first or second embodiment. The light-emitting element may be an organic light-emitting element. The optical film 1404 may be a filter that transmits light and improves the color rendering of the light source. The light diffusion unit can effectively diffuse light from the light source for illumination purposes, etc., and deliver the light over a wide area. The optical film 1404 and the light diffusion unit 1405 may be provided on the light-emitting side of the illumination device. If necessary, a cover may be provided on the outermost surface.

[0093] The lighting device is, for example, a device for illuminating a room. The lighting device may emit white, daylight white, or any other color from blue to red. It may have a dimming circuit for dimming these colors. The lighting device may have the light-emitting device according to embodiments 1 and 2 and a power supply circuit connected thereto. An organic light-emitting element can be used as the light-emitting element of the light-emitting device. The power supply circuit is a circuit that converts AC voltage into DC voltage. Furthermore, white has a color temperature of 4200K, and daylight white has a color temperature of 5000K. The lighting device may have a color filter.

[0094] The lighting device according to this embodiment may also include a heat dissipation unit, which dissipates heat from within the device to the outside, and may be made of a material such as a metal with a high specific heat capacity or liquid silicon.

[0095] 17(b) is a schematic diagram of an automobile, which is an example of a moving body according to this embodiment, using the light emitting device according to Embodiments 1 and 2. The automobile has tail lamps, which are an example of a lighting fixture. The automobile 1500 has tail lamps 1501, and may be configured to turn on the tail lamps when braking or the like is performed.

[0096] The tail lamp 1501 may include the light emitting device according to the first or second embodiment. The tail lamp may include a protective member for protecting the light emitting device. The protective member may be made of any material as long as it has a certain degree of strength and is transparent, but it is preferably made of polycarbonate or the like. Polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.

[0097] An automobile 1500 may have a body 1503 and a window 1502 attached thereto. The window may be a transparent display as long as it is not a window for checking the front and rear of the automobile. The transparent display may have a light-emitting device according to Embodiments 1 and 2. In this case, the constituent materials of the electrodes and the like of the light-emitting device are made of transparent materials.

[0098] The moving body according to this embodiment may be a ship, an aircraft, a drone, or the like. The moving body may have a body and a lighting device provided on the body. The lighting device may emit light to indicate the position of the body. The lighting device has the light-emitting device according to the first or second embodiment.

[0099] 18(a) and 18(b), application examples of a display device using the light-emitting devices according to the first and second embodiments will be described. The display device can be applied to systems that can be worn as a wearable device, such as smart glasses, HMDs, and smart contact lenses. The display device used in such application examples includes an imaging device capable of photoelectrically converting visible light, and a display device capable of emitting visible light.

[0100] 18(a) illustrates glasses 1600 (smart glasses) according to one application example. An imaging device 1602 such as a CMOS sensor or SPAD is provided on the front side of a lens 1601 of the glasses 1600. Furthermore, a display device according to any of the above-described embodiments is provided on the back side of the lens 1601.

[0101] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the image capture device 1602 and the display device according to each embodiment. The control device 1603 also controls the operations of the image capture device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light onto the image capture device 1602.

[0102] FIG. 18(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612. The control device 1612 is equipped with an imaging device corresponding to the imaging device 1602 and a display device. An optical system for projecting light emitted by the display device in the control device 1612 is formed in the lens 1611, and an image is projected onto the lens 1611. The control device 1612 functions as a power source that supplies power to the imaging device and the display device, and also controls the operations of the imaging device and the display device.

[0103] The control device may have a gaze detection unit that detects the gaze of the wearer. The gaze detection may use infrared rays. The infrared light emitting unit emits infrared light toward the eyeball of the user who is gazing at the displayed image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By having a reduction means that reduces light from the infrared light emitting unit to the display unit in a planar view, degradation of image quality is reduced.

[0104] The gaze of the user relative to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be used for gaze detection using an image of the eyeball. One example is a gaze detection method based on the Purkinje image formed by reflection of irradiated light on the cornea.

[0105] More specifically, gaze detection processing is performed based on the pupil-corneal reflex method, which calculates a gaze vector representing the direction (rotation angle) of the eyeball based on the pupil image and Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0106] The display device according to this embodiment may have an imaging device having a light receiving element, and may control the image displayed on the display device based on information about the user's line of sight from the imaging device.

[0107] Specifically, the display device determines a first display area where the user gazes and a second display area other than the first display area based on the line-of-sight information. The first display area and the second display area may be determined by a control device of the display device, or may be determined by an external control device and received. In the display area of ​​the display device, the display resolution of the first display area may be controlled to be higher than the display resolution of the second display area. In other words, the resolution of the second display area may be lower than that of the first field of view area.

[0108] The display area includes a first display area and a second display area different from the first display area, and a high-priority area is determined from the first display area and the second display area based on line-of-sight information. The first and second view areas may be determined by a control device of the display device, or may be determined by an external control device and received. The resolution of the high-priority area may be controlled to be higher than the resolution of areas other than the high-priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0109] Note that AI may be used to determine the first display area and the area with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from the image of the eyeball, using as training data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be included in the display device, the imaging device, or an external device. If included in the external device, it is transmitted to the display device via communication.

[0110] When display control is performed based on visual recognition detection, the smart glasses can be preferably applied to smart glasses that further include an imaging device for capturing images of the outside world. The smart glasses can display captured external information in real time.

[0111] As described above, by using the light emitting device according to this embodiment in an apparatus, it is possible to provide a stable display with good image quality even over a long period of time.

[0112] (Other embodiments) (Item 1) A light-emitting device in which a plurality of pixels are arranged in a matrix on a semiconductor substrate, each of the plurality of pixels includes a light emitting element, a driving transistor that supplies a current to the light emitting element, and a switching transistor that controls the light emitting element; A light emitting device characterized in that the gate electrode of the switching transistor is provided on at least two of four sides surrounding a cross section of a region that becomes a channel. (Item 2) 2. The light emitting device according to item 1, wherein a portion of the gate electrode is provided in a groove in the semiconductor substrate, and the depth of the groove is more than twice the thickness of the gate insulating film. (Item 3) 3. The light emitting device according to item 2, wherein the depth of the groove is shallower than the depth of the element isolation portion. (Item 4) 4. The light emitting device according to item 2 or 3, wherein the width of the groove is equal to or less than twice the thickness of the gate electrode on the surface of the semiconductor substrate. (Item 5) 5. The light emitting device according to any one of items 1 to 4, wherein the gate electrode includes two surfaces facing the region that becomes the channel and one surface between the two surfaces. (Item 6) 6. The light-emitting device according to any one of items 1 to 5, wherein the gate electrode of the switching transistor has an inverted U-shape with respect to the bottom surface of the semiconductor substrate in a cross section perpendicular to the direction in which current flows through the channel. (Item 7) A light-emitting device described in any one of items 1 to 6, characterized in that one of the source or drain of the switching transistor is connected to a point where the first main terminal of the light-emitting element and one of the source or drain of the drive transistor are connected, and the other of the source or drain of the switching transistor is connected to a predetermined potential. (Item 8) Item 8. The light-emitting device according to item 7, characterized in that the region functioning as either the source or drain of the switching transistor and the region functioning as either the source or drain of the driving transistor share a diffusion region of the semiconductor substrate. (Item 9) 9. The light emitting device according to any one of items 1 to 8, wherein the gate electrode of the driving transistor has a planar structure. (Item 10) 10. The light emitting device according to any one of items 1 to 9, wherein the driving transistor has an LDD structure. (Item 11) 11. The light emitting device according to any one of items 1 to 10, wherein at least one of the driving transistor and the switching transistor includes silicide in a region where at least one of the source and the drain is disposed. (Item 12) a photosensitive member, an exposure light source for exposing the photosensitive member, a developing device for applying a developer to the exposed photosensitive member, and a transfer device for transferring an image developed by the developing device onto a recording medium, 11. An image forming apparatus, characterized in that the exposure light source comprises the light emitting device according to any one of items 1 to 10. (Item 13) 11. An imaging device comprising: an optical unit having a plurality of lenses; an imaging element that receives light that has passed through the optical unit; and a display unit that displays an image captured by the imaging element, wherein the display unit comprises the light-emitting device according to any one of items 1 to 10. (Item 14) 11. A display device comprising: a display unit having the light-emitting device according to any one of items 1 to 10; and a housing in which the display unit is provided. (Item 15) 11. An electronic device comprising: a display unit having the light-emitting device according to any one of items 1 to 10; a housing in which the display unit is provided; and a communication unit provided in the housing for communicating with the outside. (Item 16) 11. A lighting device comprising: a light source having the light-emitting device according to any one of items 1 to 10; and a light diffusion section or optical film that transmits light emitted by the light source. (Item 17) A moving body comprising: a lighting fixture having the light-emitting device according to any one of items 1 to 10; and a body on which the lighting fixture is mounted. (Item 18) 1. A wearable device having a display device for displaying an image, A wearable device characterized in that the display device has the light-emitting device described in any one of items 1 to 10.

[0113] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0114] 202: Drive transistor 204: Switching transistor 301, 307: Gate electrode 400: Substrate 401: P-type substrate 402: N-type well 403: Element isolation portion 404: Channel region 405: Gate insulating film 601: Interlayer film

Claims

1. A light-emitting device in which a plurality of pixels are arranged in a matrix on a semiconductor substrate, each of the plurality of pixels includes a light emitting element, a driving transistor that supplies a current to the light emitting element, and a switching transistor that controls the light emitting element; A light emitting device characterized in that the gate electrode of the switching transistor is provided on at least two of four sides surrounding a cross section of a region that becomes a channel.

2. 2. The light emitting device according to claim 1, wherein a portion of the gate electrode is provided in a groove in the semiconductor substrate, and the depth of the groove is greater than twice the thickness of the gate insulating film.

3. 3. The light emitting device according to claim 2, wherein the depth of the groove is shallower than the depth of the element isolation portion.

4. 3. The light emitting device according to claim 2, wherein the width of the groove is equal to or less than twice the thickness of the gate electrode on the surface of the semiconductor substrate.

5. 2. The light emitting device according to claim 1, wherein the gate electrode includes two surfaces facing the region that becomes the channel, and one surface between the two surfaces.

6. 2. The light emitting device according to claim 1, wherein the gate electrode of the switching transistor has an inverted U-shape with respect to the bottom surface of the semiconductor substrate in a cross section perpendicular to the direction in which current flows through the channel.

7. The light-emitting device according to claim 1, characterized in that one of the source or drain of the switching transistor is connected to a point where the first main terminal of the light-emitting element and one of the source or drain of the driving transistor are connected, and the other of the source or drain of the switching transistor is connected to a predetermined potential.

8. 8. The light-emitting device according to claim 7, wherein a region functioning as either the source or drain of the switching transistor and a region functioning as either the source or drain of the driving transistor share a diffusion region of the semiconductor substrate.

9. 2. The light emitting device according to claim 1, wherein the gate electrode of the driving transistor has a planar structure.

10. 2. The light emitting device according to claim 1, wherein the driving transistor has an LDD structure.

11. 2. The light emitting device according to claim 1, wherein at least one of the driving transistor and the switching transistor includes silicide in a region where at least one of the source and the drain is disposed.

12. a photosensitive member, an exposure light source for exposing the photosensitive member, a developing device for applying a developer to the exposed photosensitive member, and a transfer device for transferring an image developed by the developing device onto a recording medium, An image forming apparatus, comprising the light emitting device according to claim 1 as the exposure light source.

13. 12. An imaging device comprising: an optical section having a plurality of lenses; an imaging element that receives light that has passed through the optical section; and a display section that displays an image captured by the imaging element, wherein the display section comprises a light-emitting device according to any one of claims 1 to 11.

14. A display device comprising: a display portion having the light-emitting device according to claim 1; and a housing in which the display portion is provided.

15. 12. An electronic device comprising: a display unit having the light-emitting device according to claim 1; a housing in which the display unit is provided; and a communication unit provided in the housing for communicating with an external device.

16. 12. An illumination device comprising: a light source having the light-emitting device according to claim 1; and a light diffusion portion or an optical film that transmits light emitted by the light source.

17. A moving body comprising: a lighting fixture having the light-emitting device according to any one of claims 1 to 11; and a body on which the lighting fixture is provided.

18. 1. A wearable device having a display device for displaying an image, A wearable device, wherein the display device comprises the light-emitting device according to claim 1 .

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