JP7206629B2 - Light-emitting device and projector - Google Patents

Description

The present invention relates to a light emitting device and a projector.

Mercury lamps, which have long been widely used as light sources for projectors, have problems with their lifespan, such as gradual dimming and sudden burnout, as well as problems with mercury regulations. ing.

For example, Patent Literature 1 describes a projector in which 300 (15×20) LED lamps having a plurality of LED chips are two-dimensionally arranged on an LED substrate at an arrangement pitch of 4 mm.

JP 2006-317935 A

The light source (light emitting device) of the projector as described above is desired to have high heat dissipation.

One aspect of the light-emitting device according to the present invention is
a first semiconductor layer;
a second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light by current injection;
has
In a plan view seen from the lamination direction of the first semiconductor layer and the light emitting layer, the light emitting layer has
a first part;
a second portion projecting in a first direction from the first portion;
a third portion projecting in a second direction from the first portion;
have

In one aspect of the light-emitting device,
a first electrode electrically connected to the first semiconductor layer;
a second electrode in contact with the second semiconductor layer;
has
The second electrode overlaps the light-emitting layer in a plan view viewed from the stacking direction,
A contact region between the second semiconductor layer and the second electrode is, in a plan view viewed from the stacking direction,
a first region overlapping the second portion;
a second region overlapping the third portion;
has
A size of the first region in a direction orthogonal to the first direction and a size of the second region in a direction orthogonal to the second direction may be 1 μm or more and 5 μm or less.

In one aspect of the light-emitting device,
A size of the first region in a direction orthogonal to the first direction and a size of the second region in a direction orthogonal to the second direction may be 1 μm or more and 2 μm or less.

In one aspect of the light-emitting device,
The first direction and the second direction may be the same direction.

In one aspect of the light-emitting device,
One aspect of the projector according to the present invention is
an aspect of the light-emitting device;
a projection device for projecting light emitted from the light emitting device;
have

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. 1 is a plan view schematically showing a light emitting device according to a first embodiment; FIG. 1 is a plan view schematically showing a light emitting device according to a first embodiment; FIG. 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light emitting device according to the first embodiment; The top view which shows typically the light-emitting device which concerns on the 1st modification of 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the 2nd modification of 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the 3rd modification of 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. The top view which shows typically the light-emitting device which concerns on 2nd Embodiment. FIG. 11 is a diagram schematically showing a projector according to a third embodiment; FIG. FIG. 11 is a diagram schematically showing a projector according to a first modified example of the third embodiment; FIG. FIG. 11 is a diagram schematically showing a projector according to a second modified example of the third embodiment; FIG. 4 is a graph showing the relationship between current density and optical power density;

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the embodiments described below do not unduly limit the scope of the invention described in the claims. Moreover, not all the configurations described below are essential constituent elements of the present invention.

1. First Embodiment 1.1. Light Emitting Device First, the light emitting device according to the first embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a light emitting device 100 according to the first embodiment. FIG. 2 is a plan view schematically showing the light emitting device 100 according to the first embodiment. 1 is a sectional view taken along line II of FIG. 1 and 2, X-axis, Y-axis, and Z-axis are illustrated as three mutually orthogonal axes.

The light emitting device 100 has, for example, a substrate 10, a light emitting element 20, an insulating layer 40, and a lens 50, as shown in FIGS. For convenience, the illustration of the second electrode 32 and the insulating layer 40 of the light emitting element 20 is omitted in FIG.

Substrate 10 is, for example, a sapphire substrate. The substrate 10 can transmit light generated in the light emitting layer 24 of the light emitting element 20, for example.

The light emitting element 20 is provided on the substrate 10 . A plurality of light emitting elements 20 are provided. As shown in FIG. 2, the plurality of light emitting elements 20 are arranged in a plan view from the stacking direction (the Z-axis direction in the illustrated example) of the first semiconductor layer 22 and the light emitting layer 24 of the light emitting elements 20 (hereinafter simply referred to as " In a plan view), they are provided in a matrix. The plurality of light emitting elements 20 are arranged at the same pitch in the X-axis direction and the Y-axis direction, for example. The number of light-emitting elements 20 is not particularly limited, but is, for example, about 10000 (100×100, 100 in the X-axis direction and 100 in the Y-axis direction). The light emitting element 20 is, for example, an LED. In the illustrated example, the plurality of light emitting elements 20 is a square array arranged at a pitch p in a first direction and a second direction orthogonal to the first direction. It may be a hexagonal array arranged at a pitch p in a direction and in a second direction that is 60° from the first direction.

In the present invention, "upper" means the direction away from the substrate 10 when viewed from the light emitting layer 24 of the light emitting element 20 in the lamination direction of the first semiconductor layer 22 and the light emitting layer 24 of the light emitting element 20. “Lower” means the direction toward the substrate 10 when viewed from the light emitting layer 24 in the stacking direction. In the illustrated example, "top" is the +Z-axis direction side, and "bottom" is the -Z-axis direction side.

The light emitting element 20 has, for example, a first semiconductor layer 22, a light emitting layer 24, a second semiconductor layer 26, a first electrode 30, and a second electrode 32, as shown in FIG. .

The first semiconductor layer 22 is provided on the substrate 10 . The first semiconductor layer 22 is provided between the substrate 10 and the light emitting layer 24 . The thickness of the first semiconductor layer 22 is, for example, about 5 μm. The first semiconductor layer 22 is, for example, an n-type GaN layer doped with Si. In the illustrated example, the first semiconductor layer 22 is continuous in the adjacent light emitting elements 20 , and the first semiconductor layer 22 is one common layer in the plurality of light emitting elements 20 .

A portion of the first semiconductor layer 22, the light emitting layer 24, and the second semiconductor layer 26 constitute, for example, a columnar portion 28. As shown in FIG. In the plurality of light emitting elements 20, the columnar portions 28 are provided separately from each other.

The light emitting layer 24 is provided on the first semiconductor layer 22 as shown in FIG. The light emitting layer 24 is provided between the first semiconductor layer 22 and the second semiconductor layer 26 . The light-emitting layer 24 has, for example, a multiple quantum well (MQW) structure in which five pairs of InGaN layers with a thickness of about 2.5 nm and GaN layers with a thickness of about 12 nm are alternately stacked. The light-emitting layer 24 is a layer capable of generating light when current is injected.

Light-emitting layer 24 has side surfaces 25 . In the illustrated example, the side surfaces 25 are covered with an insulating layer 40 . Here, FIG. 3 is an enlarged view of FIG. As shown in FIG. 3, the light-emitting layer 24 has a first portion 24a, a second portion 24b, and a third portion 24c in plan view.

The first portion 24a of the light emitting layer 24 has, for example, a shape whose longitudinal direction is in the Y-axis direction. In the illustrated example, the shape of the first portion 24a is rectangular in plan view.

The second portion 24b of the light emitting layer 24 protrudes from the first portion 24a in the first direction (−X-axis direction in the illustrated example). The second portion 24b is connected to, for example, the +Y-axis direction end of the first portion 24a and extends in the −X-axis direction. The second portion 24b has, for example, a shape whose longitudinal direction is in the X-axis direction. In the illustrated example, the shape of the second portion 24b is rectangular in plan view.

The third portion 24c of the light emitting layer 24 protrudes from the first portion 24a in the second direction (−X-axis direction in the illustrated example). That is, the first direction and the second direction are the same direction. The third portion 24c is connected to, for example, the end of the first portion 24a on the -Y-axis direction and extends in the -X-axis direction. The third portion 24c has, for example, a shape whose longitudinal direction is in the X-axis direction. In the illustrated example, the shape of the third portion 24c is rectangular in plan view. Although not shown, the first direction and the second direction may be different directions.

The light-emitting layer 24 has, for example, a shape in which the notch 2 is provided in a rectangular shape in plan view. The notch 2 is positioned between the second portion 24b and the third portion 24c of the light emitting layer 24 in plan view.

The second semiconductor layer 26 is provided on the light emitting layer 24 as shown in FIG. The thickness of the second semiconductor layer 26 is, for example, about 150 nm. The second semiconductor layer 26 is a layer having a conductivity type different from that of the first semiconductor layer 22 . The second semiconductor layer 26 is, for example, a p-type GaN layer doped with Mg. The second semiconductor layer 26 has, for example, the same shape as the light emitting layer 24 in plan view. The columnar portion 28 has, for example, the same shape as the light emitting layer 24 in plan view.

In the light-emitting device 100, the p-type second semiconductor layer 26, the impurity-undoped light-emitting layer 24, and the n-type first semiconductor layer 22 form a pin diode. The semiconductor layers 22 and 26 are layers having a bandgap larger than that of the light emitting layer 24 . In the light-emitting device 100 , when a forward bias voltage of a pin diode is applied (when a current is injected) between the first electrode 30 and the second electrode 32 , recombination of electrons and holes occurs in the light-emitting layer 24 . This recombination produces light emission.

Light generated in the light-emitting layer 24 (light directed in the −Z-axis direction) is transmitted through the substrate 10 and emitted. Light generated in the light emitting layer 24 (light directed in the +Z-axis direction) is reflected by the second electrode 32, for example. In FIG. 1, arrows indicate light (rays) generated in the light-emitting layer 24 and transmitted through the substrate 10 .

The first electrode 30 is provided on the first semiconductor layer 22 . In the illustrated example, the first electrode 30 is in contact with the first semiconductor layer 22 . The first electrode 30 may be in ohmic contact with the first semiconductor layer 22 . The first electrode 30 is electrically connected to the first semiconductor layer 22 .

The first electrode 30 is one electrode for injecting current into the light emitting layer 24 . As the first electrode 30, for example, a Ti layer and an Al layer are laminated in this order from the first semiconductor layer 22 side. In the example shown in FIG. 2, the first electrodes 30 of the adjacent light emitting elements 20 are continuous, and the first electrodes 30 of the plurality of light emitting elements 20 are provided in a grid pattern as one common electrode. there is The first electrode 30 is spaced apart from the columnar portion 28 and provided so as to surround the columnar portion 28 .

The second electrode 32 is provided on the second semiconductor layer 26 as shown in FIG. The second electrode 32 is in contact with the second semiconductor layer 26 . The second electrode 32 may be in ohmic contact with the second semiconductor layer 26 . The second electrode 32 overlaps the light emitting layer 24 in plan view. The second electrode 32 is electrically connected to the second semiconductor layer 26 . In the illustrated example, the second electrode 32 is also provided on the insulating layer 40 .

The second electrode 32 is the other electrode for injecting current into the light emitting layer 24 . The material of the second electrode 32 is, for example, a conductor having a high reflectance with respect to the light generated in the light emitting layer 24, such as an APC alloy that is an alloy of Ag, Pd and Cu. In the illustrated example, the second electrodes 32 are continuous in the adjacent light emitting elements 20 , and the second electrode 32 is one common electrode in the plurality of light emitting elements 20 .

The contact region 34 between the second electrode 32 and the second semiconductor layer 26 has a first region 34a and a second region 34b, as shown in FIG. The first region 34a overlaps the second portion 24b of the light emitting layer 24 in plan view. The second region 34b overlaps the third portion 24c of the light emitting layer 24 in plan view.

The size of the first region 34a of the contact region 34 in the direction orthogonal to the first direction (the size in the Y-axis direction in the illustrated example) L1 is, for example, 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less. be. Similarly, the size of the second region 34b in the direction orthogonal to the second direction (the size in the Y-axis direction in the illustrated example) L2 is, for example, 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less. .

The insulating layer 40 is provided around the columnar portion 28 and on the first semiconductor layer 22 and the first electrode 30, as shown in FIG. The insulating layer 40 electrically separates the first electrode 30 and the second electrode 32 . The insulating layer 40 is, for example, a silicon oxide layer (eg, SiO ₂ layer).

A lens 50 is provided below the substrate 10 . The lens 50 is adhered, for example, to the bottom surface of the substrate 10 . In the illustrated example, the lens 50 is a convex lens having a flat entrance surface 51a on the substrate 10 side and a curved exit surface 51b on the side opposite to the substrate 10 . A plurality of lenses 50 are provided. A plurality of lenses 50 constitute a lens array 52 . Lens array 52 is, for example, a microlens array (MLA).

Lens 50 is provided corresponding to light emitting element 20 . That is, light emitted from one light emitting element 20 enters one lens 50 . In the illustrated example, the columnar portion 28 of one light emitting element 20 is arranged inside the outer edge of one lens 50 when viewed from the Z-axis direction. The material of the lens 50 is glass, for example. The lens 50 can narrow the radiation angle of the light emitted in Lambertian from the light emitting element 20 .

The light emitting device 100 has, for example, the following features.

In the light-emitting device 100, the light-emitting layer 24 has a first portion 24a, a second portion 24b protruding from the first portion 24a in the first direction, and a second portion protruding from the first portion 24a in the second direction in plan view. and a third portion. Therefore, in the light-emitting device 100, the area of the side surface 25 of the light-emitting layer 24 should be increased compared to the case where the light-emitting layer 24 has a rectangular shape in plan view (compared to the case where the notch 2 is not provided). can be done. As a result, the light-emitting device 100 can efficiently dissipate the heat generated in the light-emitting layer 24, and can have high heat dissipation. Therefore, in the light-emitting device 100, for example, the junction temperature of the light-emitting element 20 can be lowered, and higher current density can be endured. As a result, the light-emitting device 100 can emit bright light (increased brightness).

In the light emitting device 100, the contact region 34 between the second semiconductor layer 26 and the second electrode 32 includes, in plan view, a first region 34a that overlaps with the second portion 24b, a second region 34b that overlaps with the third portion 24c, The size L1 of the first region 34a in the direction orthogonal to the first direction and the size L2 of the second region 34b in the direction orthogonal to the second direction are 1 μm or more and 5 μm or less. Therefore, in the light-emitting device 100, it is possible to suppress the occurrence of a droop phenomenon in which the light-emitting efficiency is reduced when a large amount of power is applied to the light-emitting element (for details, see "Experimental Example" described later).
, can emit brighter light.

In the light emitting device 100, the size L1 of the first region 34a and the size L2 of the second region 34b are 1 μm or more and 2 μm or less. Therefore, in the light-emitting device 100, it is possible to further suppress the occurrence of the droop phenomenon (for details, see "Experimental Example" described later).

In the light emitting device 100, the first direction and the second direction are the same direction. Therefore, in the light emitting device 100, the area of the emission surface from which the light is emitted can be reduced compared to, for example, the case where the first direction and the second direction are opposite to each other. Light that does not enter the lens 50 and becomes a loss can be reduced.

Although the GaN-based light-emitting element 20 that emits blue light has been described above, the light-emitting element can emit green light and red light by using semiconductor layers such as GaP-based and GaAs-based semiconductor layers. .

In the above description, the first semiconductor layer 22 is an n-type semiconductor layer and the second semiconductor layer 26 is a p-type semiconductor layer. Yes, the second semiconductor layer 26 may be an n-type semiconductor layer.

Although not shown, a heat sink may be provided on the +Z-axis direction side of the second electrode 32 . A heat sink may be adhered to the second electrode 32 . The material of the heat sink is copper, aluminum, or the like. The heat sink can efficiently dissipate the heat generated in the light emitting element 20 .

1.2. Method for Manufacturing Light Emitting Device Next, a method for manufacturing the light emitting device 100 according to the first embodiment will be described with reference to the drawings. FIG. 4 is a cross-sectional view schematically showing the manufacturing process of the light emitting device 100 according to the first embodiment.

As shown in FIG. 4, the first semiconductor layer 22, the light emitting layer 24, and the second semiconductor layer 26 are epitaxially grown on the substrate 10 in this order. Examples of epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

As shown in FIG. 1, the second semiconductor layer 26, the light emitting layer 24, and the first semiconductor layer 22 are patterned to form a columnar portion 28. As shown in FIG. Patterning is performed, for example, by photolithography and etching.

Next, a first electrode 30 is formed on the first semiconductor layer 22 . The first electrode 30 is formed by, for example, a vacuum deposition method.

Next, an insulating layer 40 is formed on the semiconductor layers 22 and 26 and the first electrode 30 . The insulating layer 40 is formed by, for example, a spin coating method, a CVD (Chemical Vapor Deposition) method, or the like. The insulating layer 40 is then patterned to expose the second semiconductor layer 26 .

Next, a second electrode 32 is formed on the second semiconductor layer 26 and the insulating layer 40 . The second electrode 32 is formed by, for example, a vacuum deposition method.

Next, the lens array 52 is adhered to the bottom surface of the substrate 10, for example by an adhesive.

The light emitting device 100 can be manufactured through the above steps.

In the above description, the semiconductor layers 22 and 26 and the light-emitting layer 24 are epitaxially grown, and then the semiconductor layers 22 and 26 and the light-emitting layer 24 are patterned to form the columnar portion 28. First, the mask layer is formed. (not shown), and then, using the mask layer as a mask, the semiconductor layers 22 and 26 and the light emitting layer 24 may be epitaxially grown to form the columnar portion 28 .

1.3. Modification of Light Emitting Device 1.3.1. First Modification Next, a light emitting device according to a first modification of the first embodiment will be described with reference to the drawings. FIG. 5 is a plan view schematically showing the light emitting device 110 according to the first modified example of the first embodiment. For convenience, illustration of the second electrode 32 and the insulating layer 40 is omitted in FIG. 5 and FIGS. 6 and 7 described later. In addition, in FIG. 5 and FIGS. 6 and 7 described later, the X-axis, Y-axis, and Z-axis are shown as three mutually orthogonal axes.

Hereinafter, in the light emitting device 110 according to the first modified example of the first embodiment, differences from the example of the light emitting device 100 described above will be described, and description of the same points will be omitted.

As shown in FIG. 5, the light-emitting device 110 differs from the above-described light-emitting device 100 in that the light-emitting layer 24 has a fourth portion 24d.

The fourth portion 24d protrudes, for example, in the -X-axis direction from the first portion 24a. In the illustrated example, the shape of the fourth portion 24d is rectangular in plan view. The fourth portion 24d is positioned between the second portion 24b and the third portion 24c in plan view.

The contact area 34 has a third area 34c overlapping the fourth portion 24d in plan view. The size of the third region 34c in the Y-axis direction is, for example, 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less.

In the light-emitting device 110, since the light-emitting layer 24 has the fourth portion 24d, it can have higher heat dissipation than the light-emitting device 100, for example.

1.3.2. Second Modification Next, a light emitting device according to a second modification of the first embodiment will be described with reference to the drawings. FIG. 6 is a plan view schematically showing a light emitting device 120 according to a second modification of the first embodiment.

Hereinafter, in the light emitting device 120 according to the second modification of the first embodiment, the differences from the examples of the light emitting devices 100 and 110 described above will be described, and the description of the same points will be omitted.

As shown in FIG. 6, the light-emitting device 120 differs from the above-described light-emitting device 100 in that the light-emitting layer 24 has a fourth portion 24d, a fifth portion 24e, a sixth portion 24f, and a seventh portion 24g.

The fifth portion 24e, the sixth portion 24f, and the seventh portion 24g, for example, protrude in the +X-axis direction from the first portion 24a. In the illustrated example, the shapes of the fifth portion 24e, the sixth portion 24f, and the seventh portion 24g are rectangular in plan view. The light-emitting layer 24 has, for example, a shape symmetrical with respect to an imaginary straight line (not shown) passing through the center of the first portion 24a and parallel to the Y-axis in plan view.

The contact region 34 includes, in plan view, a third region 34c overlapping with the fourth portion 24d, a fourth region 34d overlapping with the fifth portion 24e, a fifth region 34e overlapping with the sixth portion 24f, and a seventh portion 24g. It has the 6th area|region 34f which overlaps. The size of the fourth region 34d, the fifth region 34e, and the sixth region 34f in the Y-axis direction is, for example, 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less.

In the light-emitting device 120, the light-emitting layer 24 has the fourth portion 24d, the fifth portion 24e, the sixth portion 24f, and the seventh portion 24g. can.

1.3.3. Third Modification Next, a light emitting device according to a third modification of the first embodiment will be described with reference to the drawings. FIG. 7 is a plan view schematically showing a light emitting device 130 according to a third modified example of the first embodiment.

Hereinafter, in the light emitting device 130 according to the third modification of the first embodiment, differences from the light emitting devices 100, 110, and 120 described above will be described, and description of the same points will be omitted.

As shown in FIG. 7, the light-emitting device 130 differs from the above-described light-emitting device 100 in that the light-emitting layer 24 has a fourth portion 24d, a fifth portion 24e, a sixth portion 24f, and a seventh portion 24g.

In the light-emitting device 130, the third portion 24c protrudes in the −X-axis direction from the central portion of the first portion 24a in the Y-axis direction. The fourth portion 24d protrudes in the −Y-axis direction from the −X-axis direction side end of the third portion 24c. The fifth portion 24e protrudes in the +X-axis direction from the −Y-axis direction end of the first portion 24a. The sixth portion 24f protrudes in the +X-axis direction from the central portion of the first portion 24a in the Y-axis direction. The seventh portion 24g protrudes in the +Y-axis direction from the +X-axis direction side end of the sixth portion 24f. The light-emitting layer 24 has, for example, a point-symmetrical shape with respect to the center of the first portion 24a in plan view.

The contact region 34 includes, in plan view, a third region 34c overlapping with the fourth portion 24d, a fourth region 34d overlapping with the fifth portion 24e, a fifth region 34e overlapping with the sixth portion 24f, and a seventh portion 24g. It has the 6th area|region 34f which overlaps. The size of the third region 34c and the sixth region 34f in the X-axis direction is, for example, 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less.

In the light-emitting device 130, the light-emitting layer 24 has the fourth portion 24d, the fifth portion 24e, the sixth portion 24f, and the seventh portion 24g. can.

2. Second Embodiment 2.1. Light-Emitting Device Next, a light-emitting device 200 according to a second embodiment will be described with reference to the drawings. FIG. 8 is a cross-sectional view schematically showing a light emitting device 200 according to the second embodiment. FIG. 9 is a plan view schematically showing the light emitting device 200 according to the second embodiment. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 8 and 9, X-axis, Y-axis, and Z-axis are illustrated as three mutually orthogonal axes.

Hereinafter, in the light emitting device 200 according to the second embodiment, differences from the example of the light emitting device 100 described above will be described, and description of the same points will be omitted.

The light emitting device 200 differs from the light emitting device 100 described above in that a drive circuit board 64 is provided between the substrate 60 and the light emitting element 20 as shown in FIG. 8 and 9, the light emitting device 200 includes, for example, a substrate 60, a heat sink 62, a drive circuit substrate 64, an insulating layer 70, a first through via 80, a second through via 82, It has a pad 84 and a wiring 86 .

In the light emitting device 200, the substrate 60 is, for example, a silicon substrate.

A heat sink 62 is provided below the substrate 60 . The heat sink 62 is adhered to the bottom surface of the substrate 60, for example. The material of the heat sink 62 is copper, aluminum, or the like. The heat sink 62 can efficiently dissipate the heat generated in the light emitting element 20 .

A drive circuit board 64 is provided on the board 60 . A drive circuit for driving the light emitting element 20 is mounted on the drive circuit board 64 . The drive circuit is implemented by, for example, CMOS (Complementary Metal Oxide Semiconductor). The drive circuit can drive the light emitting element 20 based on, for example, input image information. Therefore, one light emitting element 20 can form one pixel. Light-emitting device 200 is, for example, a self-luminous imager.

The insulating layer 70 is provided on the drive circuit board 64 . The insulating layer 70 is, for example, a silicon oxide layer.

The first through via 80 and the second through via 82 are provided through the insulating layer 70 . The material of the through vias 80 and 82 is, for example, Ti. The first through via 80 connects the drive circuit mounted on the drive circuit board 64 and the second electrode 32 of the light emitting element 20 . The second through via 82 connects the drive circuit and the pad 84 .

A pad 84 is provided on the second through via 82 . The material of the pad 84 is, for example, metal.

The wiring 86 connects the pad 84 and the first electrode 30 of the light emitting element 20 . The material of the wiring 86 is, for example, metal.

The light emitting element 20 is provided on the first through via 80 and the insulating layer 70 . The plurality of light emitting elements 20 are separated from each other. In the illustrated example, the second electrode 32, the second semiconductor layer 26, the light emitting layer 24, the first semiconductor layer 22, and the first electrode 30 are arranged in this order from the first through via 80 side. The semiconductor layers 22 and 26, the light emitting layer 24, and the electrodes 30 and 32 have, for example, the same shape in plan view.

The first electrode 30 is electrically connected to the driving circuit through the wiring 86, the pad 84, and the second through via 82. As shown in FIG. The material of the first electrode 30 is a transparent electrode such as ITO (Indium Tin Oxide). Light generated in the light emitting layer 24 passes through the first electrode 30 and enters the lens 50 .

The second electrode 32 is electrically connected to the driving circuit through the first through via 80 . For the second electrode 32, for example, an Al layer and a Ti layer are laminated in this order from the second semiconductor layer 26 side. By sufficiently smoothing and cleaning the Ti of the second electrode 32 and the Ti of the first through via 80 and applying pressure and heat, the second electrode 32 and the first through via 80 can be metal-bonded. can.

In the light-emitting device 200, the first electrode 30 and the second electrode 32 overlap the light-emitting layer 24 in plan view. In such a case, the second semiconductor layer 26 that forms the contact region 34 is the n-type semiconductor layer or the p-type semiconductor layer that has a smaller area of the contact region with the electrode. If the area of the contact region is the same, it is either one of the semiconductor layers. In the illustrated example, the second semiconductor layer 26 is a p-type semiconductor layer, and the area of the contact region 34 between the second semiconductor layer 26 and the second electrode 32 is the same as that of the first semiconductor layer 22 and the first electrode 30 . is the same as the area of the contact area of

In the light-emitting device 200 , the lens array 52 is provided on the +Z-axis direction side of the light-emitting element 20 . The lens array 52 is adhered, for example, to a supporting member (not shown).

2.2. Method for Manufacturing Light Emitting Device Next, a method for manufacturing the light emitting device 200 according to the second embodiment will be described with reference to the drawings.

Hereinafter, in the method for manufacturing the light emitting device 200 according to the second embodiment, differences from the example of the method for manufacturing the light emitting device 100 according to the first embodiment described above will be described, and the description of the same points will be omitted or simplified. .

As shown in FIG. 4, the first semiconductor layer 22, the light emitting layer 24, and the second semiconductor layer 26 are epitaxially grown on the substrate 10 in this order.

Substrate 10 is then removed by polishing and plasma etching. Next, as shown in FIG. 8, a first electrode 30 and a second electrode 32 are formed. The light emitting element 20 can be formed through the above steps. Note that the second electrode 32 may be formed before removing the substrate 10 .

Next, the substrate 60, the heat sink 62, the drive circuit board 64, the insulating layer 70, and the through vias 80 and 82 are prepared, and the light emitting element 20 is inserted into the second through via with the second electrode 32 side facing the first through via 80. It is connected to via 82 .

A pad 84 is then formed on the second through via 82 . The pads 84 are formed by, for example, a sputtering method, a plating method, or the like. Note that the pad 84 may be formed before connecting the light emitting element 20 to the first through via 80 .

Next, the insulating layer 40 is formed on the first electrodes 30 and the pads 84 . The insulating layer 40 is then patterned to expose the first electrodes 30 and the pads 84 .

Next, wirings 86 are formed on the first electrodes 30 and the pads 84 . The wiring 86 is formed by, for example, a sputtering method, a plating method, or the like.

Next, the lens array 52 is arranged. The heat sink 62 may be adhered to the rear surface of the substrate 60 after the lens array 52 is arranged.

The light emitting device 200 can be manufactured through the above steps.

Although not shown, the light-emitting layer 24 of the light-emitting device 200 may have first to seventh portions like the light-emitting devices 110, 120, and 130 described above.

3. Third Embodiment 3.1. Projector Next, a projector according to the third embodiment will be described with reference to the drawings. FIG. 10 is a diagram schematically showing a projector 400 according to the third embodiment.

A projector according to the present invention has a light emitting device according to the present invention. A projector 400 having the light emitting device 100 as the light emitting device according to the present invention will be described below.

The projector 400 has a housing (not shown), and a red light source 100R, a green light source 100G, and a blue light source 100B that emit red light, green light, and blue light, respectively, provided in the housing. . Each of red light source 100R, green light source 100G, and blue light source 100B is light emitting device 100 . For the sake of convenience, FIG. 10 omits illustration of a housing that constitutes the projector 400 . Also, in FIG. 10, the light sources 100R, 100G, and 100B are illustrated in a simplified manner.

The projector 400 further includes transmissive liquid crystal light valves (light modulation devices) 402R, 402G, and 402B and a projection lens (projection device) 406 provided in the housing. The projector 400 is an LCD (Liquid Crystal Display) projector.

Light emitted from the light sources 100R, 100G, and 100B enters the liquid crystal light valves 402R, 402G, and 402B. Each of the liquid crystal light valves 402R, 402G, and 402B modulates incident light according to image information. A projection lens 406 magnifies the images (images) formed by the liquid crystal light valves 402 R, 402 G, and 402 B and projects them onto a screen (display surface) 408 . That is, the projection lens 406 projects the light emitted from the light sources 100R, 100G, and 100B onto the screen.

The projector 400 can also have a cross dichroic prism (color light combining means) 404 that combines the lights emitted from the liquid crystal light valves 402 R, 402 G, and 402 B and guides them to the projection lens 406 .

The three colored lights modulated by the liquid crystal light valves 402R, 402G, and 402B enter the cross dichroic prism 404. FIG. The cross dichroic prism 404 is formed by bonding four rectangular prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films synthesize three color lights to form light representing a color image. The combined light is projected onto a screen 408 by a projection lens 406, which is a projection optical system, to display an enlarged image.

3.2. Modified example of projector 3.2.1. First Modification Next, a projector according to a first modification of the third embodiment will be described with reference to the drawings. FIG. 11 is a cross-sectional view schematically showing a projector 410 according to the first modified example of the third embodiment. For convenience, FIG. 11 shows the light sources 100R, 100G, and 100B in a simplified manner. Also, in FIG. 11, illustration of the screen 408 is omitted.

Hereinafter, in the projector 410 according to the first modified example of the third embodiment, differences from the example of the projector 400 described above will be described, and description of the same points will be omitted. This is the same for a projector according to a second modification of the third embodiment, which will be described later.

In the projector 400 described above, as shown in FIG. 10, a transmissive liquid crystal light valve is used as the light modulation device. On the other hand, as shown in FIG. 11, the projector 410 uses a DMD (Digital Micromirror Device, registered trademark) 418 as an optical modulation device. The projector 410 is a DLP (Digital Light Processing, registered trademark) projector.

The projector 410 has light sources 100R, 100G, 100B, dichroic filters 411, 412, lenses 413, 414, 415, 416, a total internal reflection prism (TIR prism) 417, a DMD 418, and a projection lens 406. are doing.

Light emitted from the red light source 100 R is reflected by the dichroic filter 411 and enters the lens 413 . Light emitted from the green light source 100 G is reflected by the dichroic filter 412 , passes through the dichroic filter 411 , and enters the lens 413 . Light emitted from the blue light source 100B passes through the dichroic filters 411 and 412 and enters the lens 413 . Lights emitted from the light sources 100R, 100G, and 100B are synthesized in the dichroic filter 411. FIG.

The light emitted from lens 413 enters TIR prism 417 via lenses 414 , 415 and 416 . The lens 414 is a rod lens (integrator), and by repeating total reflection of light inside the lens 414, the illuminance distribution at the exit of the lens 414 can be made substantially uniform. Lenses 413, 415, and 416 are, for example, condensing lenses.

The light incident on the TIR prism 417 is reflected by the reflecting portion 417 a and enters the DMD 418 .

The DMD 418 modulates and reflects incident light according to image information. Light reflected by DMD 418 passes through TIR prism 417 and enters projection lens 406 .

3.2.2. Second Modification Next, a projector according to a second modification of the third embodiment will be described with reference to the drawings. FIG. 12 is a cross-sectional view schematically showing a projector 420 according to a second modified example of the third embodiment. For convenience, illustration of the screen 408 is omitted in FIG.

As shown in FIG. 10, the projector 400 described above has the light sources 100R, 100G, and 100B, which are the light emitting devices 100. As shown in FIG. On the other hand, the projector 420 has light sources 200R, 200G, and 200B, which are light emitting devices 200, as shown in FIG. Since the light-emitting device 200 is a self-luminous imager capable of forming pixels, the projector 420 does not have a separate light modulation device. Therefore, miniaturization can be achieved. For convenience, FIG. 12 shows the light sources 200R, 200G, and 200B in a simplified manner.

The red light source 200R, green light source 200G, and blue light source 200B emit red light, green light, and blue light, respectively. In addition, projector 420 has a Philips prism 422 .

Lights emitted from the light sources 200 R, 200 G, and 200 B are synthesized in the Philips prism 422 and enter the projection lens 406 . For example, the light emitted from the light sources 200R, 200G, and 200B is non-polarized light, so the Philips prism 422 that is less dependent on polarization is suitable.

In addition, the light emitting device according to the present invention can also be applied to apparatuses such as HMDs (head mounted displays) and HUDs (head up displays) to which projectors are applied. In addition to projectors, the light-emitting device according to the present invention can be widely applied to devices that require bright light with directivity, such as automobile headlights and spotlights.

4. Experimental Examples Experimental examples are shown below to describe the present invention more specifically. In addition, the present invention is not limited at all by the following experimental examples.

As an experiment corresponding to the light-emitting device 100 using an LED as the light-emitting element 20, the size of the contact region of the LED (the contact region between the second semiconductor layer and the second electrode) was variously changed, and its characteristics were measured. went. However, the shape of the second semiconductor layer, the second electrode, and the contact area (hereinafter also simply referred to as "contact area") is square. Also, isolated LEDs were used instead of LEDs arranged in a matrix.

FIG. 13 is a graph showing the relationship between the current density injected into the light emitting layer of the LED and the optical power density of the LED. The size of the contact area was changed from 100 μm square to 1 μm square.

As shown in FIG. 13, the optical power density tends to increase as the current density increases, but saturates at a certain current density. This is due to the droop phenomenon in which the luminous efficiency decreases when a large amount of power is applied to the LED.

As shown in FIG. 13, a smaller contact area size can withstand higher optical power densities. It can be understood that this is because the smaller the size of the contact region, the lower the junction temperature due to heat dissipation from the side surface of the light emitting layer, and the quantum efficiency can be maintained. Therefore, it was found that the light power density can be increased by setting the size of one side of the contact region to 5 μm or less.

Furthermore, as shown in FIG. 13, the effect of suppressing the droop phenomenon was saturated when the size of the contact area was 2 μm square. Therefore, it was found that the optical power density can be increased by setting the size of one side of the contact region to 2 μm or less.

Note that if one side of the contact region is smaller than 1 μm, it becomes difficult to form the contact region with high accuracy, and the yield may decrease.

From the above, the size L1 in the Y-axis direction of the first region 34a of the contact region 34 and the size L2 in the Y-axis direction of the second region 34b of the contact region 34 are 1 μm or more and 5 μm or less, preferably 1 μm or more and 2 μm or less. By doing so, it can be said that the occurrence of the droop phenomenon can be suppressed, the optical power density can be increased, and brighter light can be emitted. In addition, it can be said that a decrease in yield can be suppressed.

The present invention may omit a part of the configuration or combine each embodiment and modifications as long as the features and effects described in the present application are provided.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same function, method, and result, or configurations that have the same purpose and effect). Moreover, the present invention includes configurations obtained by replacing non-essential portions of the configurations described in the embodiments. In addition, the present invention includes a configuration that achieves the same effects or achieves the same purpose as the configurations described in the embodiments. In addition, the present invention includes configurations obtained by adding known techniques to the configurations described in the embodiments.

2... Notch 10... Substrate 20... Light-emitting element 22... First semiconductor layer 24... Light-emitting layer 24a... First part 24b... Second part 24c... Third part 24d... Fourth part 24e... Fifth part 24f... Sixth part 24g... Seventh part 25... Side surface 26... Second semiconductor layer 28... Columnar part 30... First electrode 32... Second electrode 34... Contact region , 34a...first area, 34b...second area, 34c...third area, 34d...fourth area, 34e...fifth area, 34f...sixth area, 40...insulating layer, 50...lens, 51a...incidence surface , 51b... Emission surface 52... Lens array 60... Substrate 62... Heat sink 64... Drive circuit board 70... Insulating layer 80... First through via 82... Second through via 84... Pad 86... Wiring 100 Light emitting device 100R Red light source 100G Green light source 100B Blue light source 110, 120, 130 Light emitting device 200 Light emitting device 200R Red light source 200G Green light source 200B Blue light source , 400... Projector 402R, 402G, 402B... Liquid crystal light valve 404... Cross dichroic prism 406... Projection lens 408... Screen 410... Projector 411, 412... Dichroic filter 413, 414, 415, 416... Lens , 417... TIR prism, 417a... reflector, 418... DMD, 420... projector, 422... Philips prism

Claims (8)

a substrate;
pads provided on the substrate;
a light emitting element provided on the substrate;
a wiring that electrically connects the pad and the light emitting element;
has
The light emitting element is
a first semiconductor layer;
a second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light by current injection;
a first electrode electrically connected to the first semiconductor layer;
a second electrode in contact with the second semiconductor layer;
has
In a plan view seen from the lamination direction of the first semiconductor layer and the light emitting layer, the light emitting layer has
a first part;
a second portion projecting in a first direction from the first portion;
a third portion projecting in a second direction from the first portion;
has
In a plan view seen from the stacking direction, the wiring overlaps the light emitting element,
The wiring is provided along a side wall of the light emitting element opposite to the first direction ,
The second electrode overlaps the light-emitting layer in a plan view viewed from the stacking direction,
A contact region between the second semiconductor layer and the second electrode is, in a plan view viewed from the stacking direction,
a first region overlapping the second portion;
a second region overlapping the third portion;
has
The size of the first region in a direction perpendicular to the first direction and the second region of the second region
The size in the direction perpendicular to the direction is 1 μm or more and 5 μm or less,
part of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer constitute a columnar section;
The second electrode is provided on the second semiconductor layer,
the first electrode is provided in a portion of the first semiconductor layer that does not constitute the columnar portion;
The light-emitting device , wherein the first electrode surrounds the columnar portion while being separated from the columnar portion in plan view in the stacking direction . a substrate;
pads provided on the substrate;
a light emitting element provided on the substrate;
a wiring that electrically connects the pad and the light emitting element;
has
The light emitting element is
a first semiconductor layer;
a second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light by current injection;
has
In a plan view seen from the lamination direction of the first semiconductor layer and the light emitting layer, the light emitting layer has
a first part;
a second portion projecting in a first direction from the first portion;
a third portion projecting in a second direction from the first portion;
has
In a plan view seen from the stacking direction, the wiring overlaps the light emitting element,
The wiring is provided along a side wall of the light emitting element opposite to the first direction ,
the first direction and the second direction are the same direction,
The second part protrudes from an end of the first part on a third direction side orthogonal to the first direction in a plan view seen in the stacking direction,
The third portion protrudes from a central portion of the first portion in the third direction in a plan view seen in the stacking direction,
In a plan view viewed from the lamination direction, the light-emitting layer has
a fourth portion protruding in a fourth direction opposite to the third direction from an end of the third portion on the first direction side;
a fifth portion protruding in a fifth direction opposite to the first direction from an end of the first portion on the fourth direction side;
a sixth portion protruding in the fifth direction from a central portion of the first portion in the third direction;
and a seventh portion protruding in the third direction from an end of the sixth portion on the fifth direction side . In claim 2 ,
a first electrode electrically connected to the first semiconductor layer;
a second electrode in contact with the second semiconductor layer;
has
The second electrode overlaps the light-emitting layer in a plan view viewed from the stacking direction,
A contact region between the second semiconductor layer and the second electrode is, in a plan view viewed from the stacking direction,
a first region overlapping the second portion;
a second region overlapping the third portion;
has
The light-emitting device, wherein the size of the first region in the direction orthogonal to the first direction and the size of the second region in the direction orthogonal to the second direction are 1 μm or more and 5 μm or less. In claim 3 ,
The light-emitting device, wherein the size of the first region in the direction orthogonal to the first direction and the size of the second region in the direction orthogonal to the second direction are 1 μm or more and 2 μm or less. In claim 3 or 4 ,
part of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer constitute a columnar section;
The second electrode is provided on the second semiconductor layer,
the first electrode is provided in a portion of the first semiconductor layer that does not constitute the columnar portion;
The light-emitting device, wherein the first electrode surrounds the columnar portion while being separated from the columnar portion in plan view in the stacking direction. In any one of claims 1, 3 to 5 ,
A plurality of the light emitting elements are provided,
The light-emitting device, wherein the first electrodes of the adjacent light-emitting elements are continuous. In claim 1 ,
The light-emitting device, wherein the first direction and the second direction are the same direction. a light emitting device according to any one of claims 1 to 7;
a projection device for projecting light emitted from the light emitting device;
a projector.

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