Light-emitting components

Abstract

The present invention provides a light-emitting element that can suppress the rise of forward voltage and improve light extraction efficiency. The light-emitting element has a semiconductor laminate, which has: an n-type semiconductor layer, which includes a light extraction surface and an n-side contact surface, and the n-side contact surface is provided on the opposite side of the light extraction surface; a light-emitting layer, which is provided in a region of the n-type semiconductor layer other than the n-side contact surface; and a p-type semiconductor layer, which is provided on the light-emitting layer. When viewed from above, the p-type semiconductor layer is provided in a manner surrounding the n-side contact surface. A first insulating film is provided in a region including a central portion of the n-side contact surface. An n-side electrode having an n-contact portion is provided, and the n-contact portion is provided around the first insulating film in the n-side contact surface and in contact with the n-side contact surface.

Description

Technical Field

[0001] The present invention relates to a light emitting element. Background Art

[0002] In a light emitting element having a structure in which light is extracted from a surface of an n-type semiconductor layer opposite to an n-side contact surface in contact with an electrode, it is desired to improve the light reflection efficiency on the n-side contact surface.

[0003] Patent Document 1: (Japanese) Patent Publication No. 2016-208012 Summary of the invention

[0004] The present invention provides a light emitting element capable of suppressing the increase of forward voltage and improving light extraction efficiency.

[0005] According to one aspect of the present invention, a light-emitting element comprises a semiconductor laminate, which comprises: an n-type semiconductor layer including a light extraction surface and an n-side contact surface, wherein the n-side contact surface is arranged on the opposite side of the light extraction surface; a light-emitting layer, which is arranged in a region of the n-type semiconductor layer other than the n-side contact surface; a p-type semiconductor layer, which is arranged on the light-emitting layer; wherein, when viewed from above, the p-type semiconductor layer is arranged so as to surround the n-side contact surface, and the light-emitting element comprises: a first insulating film, which is arranged in a region including a central portion of the n-side contact surface; an n-side electrode, which has an n-contact portion, which is arranged around the first insulating film in the n-side contact surface and in contact with the n-side contact surface; and a p-side electrode, which is arranged on the p-type semiconductor layer and in contact with the p-type semiconductor layer.

[0006] According to the present invention, it is possible to improve light extraction efficiency while suppressing an increase in forward voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic top view of a light emitting element according to an embodiment of the present invention;

[0008] Figure 2 yes Figure 1 Section II-II of the;

[0009] Figure 3 is a schematic top view of a semiconductor laminate of a light-emitting element according to an embodiment of the present invention;

[0010] Figure 4 is a partially enlarged cross-sectional schematic diagram of a light emitting element according to an embodiment of the present invention;

[0011] Figure 5 is a partial top view schematic diagram of a light emitting element according to an embodiment of the present invention;

[0012] Figure 6is a graph obtained by simulating the relationship between the area of ​​the n-contact portion of the n-side electrode in contact with the n-side contact surface and the forward voltage Vf;

[0013] Figure 7 The diameter of the insulating film in the region including the central portion provided on the n-side contact surface is A curve diagram obtained by simulating the relationship between Vf and the forward voltage;

[0014] Figure 8 The diameter of the insulating film in the region including the central portion provided on the n-side contact surface is The curve diagram obtained by simulating the relationship between the light intensity Po;

[0015] Fig. 9 Yes means Figure 5 A schematic top view of another arrangement pattern of the elements shown;

[0016] Fig.10 is a schematic top view of a semiconductor laminate of a light-emitting element according to another embodiment of the present invention;

[0017] Fig.11 is a partially enlarged cross-sectional schematic diagram of a light emitting element according to another embodiment of the present invention;

[0018] Fig.12 is a partially enlarged cross-sectional schematic diagram of a light emitting element according to another embodiment of the present invention;

[0019] Fig.13 is a partially enlarged cross-sectional schematic diagram of a light emitting element according to another embodiment of the present invention;

[0020] Fig.14 It is a partially enlarged cross-sectional schematic diagram of a light emitting element according to another embodiment of the present invention.

[0021] Description of Reference Numerals

[0022] 1: light-emitting element; 10: semiconductor laminate; 11: n-type semiconductor layer; 11a: light extraction surface; 11b: n-side contact surface; 12: light-emitting layer; 13: p-type semiconductor layer; 21: p-side electrode; 22: n-side electrode; 22a: n-contact portion; 22c: external connection portion; 24: reflective film; 41-43: insulating films; 100: substrate. DETAILED DESCRIPTION

[0023] Hereinafter, the embodiments will be described with reference to the accompanying drawings. It should be noted that the same reference numerals are given to the same elements in each of the drawings.

[0024] Figure 1 It is a schematic top view of the light emitting element 1 according to the embodiment of the present invention.

[0025] Figure 2 yes Figure 1 Section II-II of the diagram.

[0026] The light emitting element 1 includes a substrate 100 and a semiconductor laminate 10 provided on the substrate 100 . The semiconductor laminate 10 includes an n-type semiconductor layer 11 provided on the substrate 100 , a light emitting layer 12 provided on the n-type semiconductor layer 11 , and a p-type semiconductor layer 13 provided on the light emitting layer 12 .

[0027] The substrate 100 has a property of transmitting light emitted by the light emitting layer 12. In addition, the substrate 100 can be used to epitaxially grow the semiconductor laminate 10. Examples of the material of the substrate 100 include sapphire, spinel (MgAl 2 O 4 ), silicon carbide (SiC), silicon, ZnS, ZnO, GaAs, diamond, lithium niobate, neodymium gallate, etc.

[0028] For the semiconductor laminate 10, for example, In X Al Y Ga 1－X－Y N (0≤X, 0≤Y, X+Y<1) and other semiconductors.

[0029] like Figure 2 As shown, the n-type semiconductor layer 11 has: a light extraction surface 11a; and an n-side contact surface 11b provided on the opposite side of the light extraction surface 11a. The light extraction surface 11a is located at the interface between the n-type semiconductor layer 11 and the substrate 100. The light from the light extraction surface 11a passes through the substrate 100 and is mainly extracted from the side of the substrate 100. In the light emitting element 1, the light from the light emitting layer 12 is mainly extracted from the side of the substrate 100.

[0030] The light emitting layer 12 and the p-type semiconductor layer 13 are not provided on the n-side contact surface 11b. For example, after the n-type semiconductor layer 11, the light emitting layer 12, and the p-type semiconductor layer 13 are epitaxially grown in sequence on the substrate 100, a portion of the stacked portion of the p-type semiconductor layer 13 and the light emitting layer 12 is removed by etching to form the n-side contact surface 11b. The portion where the p-type semiconductor layer 13 and the light emitting layer 12 are stacked remains on the n-type semiconductor layer 11 in a terrace shape.

[0031] Figure 3 It is a schematic plan view of the semiconductor laminate 10 . Figure 3 is from Figure 2 The figure is a plan view showing the light extraction surface 11a from the opposite side.

[0032] For example, a plurality of circular n-side contact surfaces 11b are provided on the surface opposite to the light extraction surface 11a of the n-type semiconductor layer 11. The light emitting layer 12 and the p-type semiconductor layer 13 are provided on the surface opposite to the light extraction surface 11a of the n-type semiconductor layer 11 except for the n-side contact surfaces 11b and the peripheral region 11c.

[0033] exist Figure 3 In the plan view shown, the light emitting layer 12 and the p-type semiconductor layer 13 are provided so as to surround the n-side contact surface 11 b .

[0034] like Figure 2 As shown in FIG. 1 , a first p-side electrode 21 is provided on the p-type semiconductor layer 13 . The first p-side electrode 21 is in contact with the upper surface of the p-type semiconductor layer 13 .

[0035] Moreover, an insulating film 41 is provided on the p-type semiconductor layer 13 so as to cover the first p-side electrode 21 and the upper surface of the p-type semiconductor layer 13. Furthermore, an insulating film 42 is provided so as to cover the insulating film 41.

[0036] The insulating film 42 covers the side surfaces of the p-type semiconductor layer 13, the side surfaces of the light emitting layer 12, and the side surfaces of the n-type semiconductor layer 11 connected to these side surfaces. That is, the insulating film 42 covers the side surfaces of the mesa portion 15 where the light emitting layer 12 and the p-type semiconductor layer 13 are stacked.

[0037] The n-side electrode 22 is provided on the insulating film 42. The insulating film 42 has a step that covers the side surfaces of the components as described above, and the n-side electrode 22 is provided along the step. The n-side electrode 22 has an n-contact portion 22a that contacts the n-side contact surface 11b, an external connection portion 22c that is provided on the insulating film 42 on the mesa portion 15, and an outer peripheral contact portion 22b that contacts the outer peripheral region 11c of the n-type semiconductor layer 11. The n-contact portion 22a, the external connection portion 22c, and the outer peripheral contact portion 22b are connected as one.

[0038] An n-side post electrode 32 is provided on the external connection portion 22c. The n-side post electrode 32 is electrically connected to the n-type semiconductor layer 11 via the n-side electrode 22.

[0039] A portion of the insulating films 41 and 42 covering the first p-side electrode 21 is opened, and a second p-side electrode 23 is provided in the opening. The second p-side electrode 23 is in contact with the first p-side electrode 21. A portion of the second p-side electrode 23 is provided on the insulating film 42. A p-side wiring electrode 31 is provided on the second p-side electrode 23. The p-side wiring electrode 31 is electrically connected to the p-type semiconductor layer 13 via the second p-side electrode 23 and the first p-side electrode 21.

[0040] Figure 4It is a schematic enlarged cross-sectional view of a region of the light emitting element 1 where the n-side contact surface 11 b is provided.

[0041] The insulating film 43 is provided in a region including the central portion of the circular n-side contact surface 11b. The n-side contact surface 11b has: a region including the central portion; and a region surrounding the region including the central portion. Furthermore, the "region including the central portion" means, when the n-side contact surface 11b is circular, a region including the center of the circle; when the n-side contact surface 11b is square, a region including the center of the inscribed circle of the square; and when the n-side contact surface 11b is annular, a region including the center of the circle formed by the inner circumference or outer circumference thereof.

[0042] Figure 5 1 is a schematic plan view showing the arrangement relationship among the n-side contact surface 11 b , the insulating film 43 , and the n-contact portion 22 a of the n-side electrode 22 in a plan view.

[0043] The insulating film 42 is formed so as to cover the entire semiconductor laminate 10, and the insulating film 42 is patterned, and the insulating film 43 remains on the n-side contact surface 11b in a circular shape, for example. Therefore, the insulating film 42 and the insulating film 43 are films of the same material, and the film thickness of the insulating film 42 and the film thickness of the insulating film 43 are substantially the same.

[0044] In the process of patterning the insulating film 42 , a portion 42 a of the insulating film 42 also remains in the outer peripheral region of the n-side contact surface 11 b in, for example, a ring shape.

[0045] The n-contact portion 22 a of the n-side electrode 22 is provided around the insulating film 43 , and is provided in, for example, an annular shape surrounding the circular insulating film 43 .

[0046] Due to the etching process of patterning the insulating film 43, as Figure 4 As shown, the cross-sectional shape of the insulating film 43 is a trapezoid having an upper base 43a and a lower base 43b longer than the upper base 43a, and the lower base 43b is located at the interface between the trapezoid and the n-side contact surface 11b.

[0047] For example, Ag, Al, Ni, Ti, Pt, or an alloy containing these metals as a main component can be preferably used as the first p-side electrode 21. The first p-side electrode 21 may be a single layer or a stack of these metal materials.

[0048] The n-side electrode 22 and the second p-side electrode 23 can be obtained, for example, by patterning a film of the same metal material. As these n-side electrode 22 and the second p-side electrode 23, for example, Ag, Al, Ni, Rh, Au, Cu, Ti, Pt, Pd, Mo, Cr, W, or alloys containing these metals as main components can be preferably used. In addition, the n-side electrode 22 and the second p-side electrode 23 can be a single layer or a stack of these metal materials.

[0049] The n-side electrode 22 and the second p-side electrode 23 include, for example, an Al film, a Ti film, a Pt film, and an Au film formed in this order from the interface side with the substrate.

[0050] For example, metals such as Cu, Au, and Ni can be preferably used as the n-side wiring electrode 32 and the p-side wiring electrode 31. The n-side wiring electrode 32 and the p-side wiring electrode 31 can be formed by, for example, electroplating.

[0051] The insulating film 41 is, for example, a silicon nitride film. The insulating film 41 prevents migration of, for example, Ag contained in the first p-side electrode 21. The insulating film 42 and the insulating film 43 are, for example, silicon oxide films.

[0052] The n-side wiring electrode 32 and the p-side wiring electrode 31 are bonded to pads formed on the wiring substrate on which the light-emitting element 1 is mounted, for example, via a conductive material such as solder. That is, with respect to the light-emitting element 1, when the n-side wiring electrode 32 and the p-side wiring electrode 31 are facing the wiring substrate, the substrate 100 and the light extraction surface 11a of the n-type semiconductor layer 11 face upward from the wiring substrate. It should be noted that the substrate 100 may also be absent.

[0053] Then, the light emitted from the light emitting layer 12 is taken out to the outside through the light extraction surface 11a. Most of the area on the opposite side of the light extraction surface 11a is covered by a metal film (for example, containing Ag, Al with good light reflectivity) constituting the p-side electrodes 21, 23 and the n-side electrode 22. Therefore, the light that is not directly emitted from the light emitting layer 12 to the light extraction surface 11a and the light reflected by the interface between the n-type semiconductor layer 11 and the substrate 100 can be reflected by the metal film and emitted to the light extraction surface 11a.

[0054] In addition, in the region including the central portion of the n-side contact surface 11b, the n-side electrode 22 is not provided, but the insulating film 43 is provided. Therefore, in the region including the central portion of the n-side contact surface 11b, the absorption of light by the metal constituting the n-side electrode 22 can be reduced, and the total reflection component at the interface between the insulating film 43 and the n-type semiconductor layer 11 can be increased. Thus, the reflectivity of the light propagating in the n-type semiconductor layer 11 and heading toward the n-side contact surface 11b at the n-side contact surface 11b is increased, so that the light extraction efficiency of the light extracted from the light extraction surface 11a side is improved.

[0055] Figure 6 This is a graph obtained by simulation of the relationship between the area of ​​the n-contact portion 22 a of the n-side electrode 22 in contact with the n-side contact surface 11 b and the forward voltage Vf at 1000 mA.

[0056] Indicates that relative to Figure 5 The diameter of the n-side contact surface 11b is shown The reduction in Vf results from the reduction in the area of ​​n-contact portion 22a.

[0057] Indicates that relative to Figure 5 The diameter of the insulating film 43 is shown The increase in Vf causes a decrease in the area of ​​the n-contact portion 22a, which changes Vf.

[0058] It should be noted that there is no Figure 4 The portion 42a of the insulating film 42 is shown. Therefore, the area of ​​the n-contact portion 22a is the area obtained by subtracting the area of ​​the insulating film 43 from the area of ​​the n-side contact surface 11b.

[0059] When the diameter of the n-side contact surface 11b When the diameter of the insulating film 43 is increased, the area of ​​the n-contact portion 22a is reduced, and the forward voltage Vf is increased. In contrast, the forward voltage Vf is not significantly increased due to the reduction in the area of ​​the n-contact portion 22a caused by the increase in the diameter of the insulating film 43.

[0060] By this Figure 6 The results show that, in the n-side contact surface 11b, the current is concentrated in the peripheral portion close to the external connection portion 22c of the n-side electrode 22, and almost no current flows in the central portion, and the current is concentrated near the periphery of the n-side contact surface 11b. Therefore, it can be said that even if the insulating film 43 is provided in the central portion of the n-side contact surface 11b and the central portion is made non-conductive, it will not hinder the power supply to the light-emitting layer 12, and the forward voltage is unlikely to increase.

[0061] Figure 7 is the diameter of the insulating film 43 This is a graph obtained by simulating the relationship between the forward voltage Vf at 1000mA. Figure 7 Indicates the average value of the forward voltage Vf.

[0062] Figure 8 is the diameter of the insulating film 43 This is a graph obtained by simulating the relationship between the current and the light intensity Po at 1000 mA. Figure 8 Indicates the average value of light intensity Po.

[0063] exist Figure 7 and Figure 8 In the simulation, the diameter of the n-side contact surface 11b is is fixed at 21μm. Figure 6 Similarly, in the peripheral area of ​​the n-side contact surface 11b, no Figure 4 A portion 42a of the insulating film 42 is shown.

[0064] Depend on Figure 7 and Figure 8 The results show that in When 12μm and When it is 16μm, it can maintain When the forward voltage Vf is the same as 0 μm (when the insulating film 43 is not provided on the n-side contact surface 11b), the total reflection area can be increased by the insulating film 43, thereby improving the light intensity Po. That is, if the light emitting element 1 is provided with the insulating film 43, the increase of the forward voltage Vf can be suppressed and the light extraction efficiency can be improved.

[0065] Depend on Figure 7 and Figure 8 The results show that the area of ​​n-type contact portion 22 a is preferably not less than 40% and not more than 70% of the area of ​​n-side contact surface 11 b .

[0066] The shapes of the n-side contact surface 11 b and the insulating film 43 are not limited to circular shapes, and may be square shapes.

[0067] like Figure 5 As shown, when the circular n-side contact surface 11b is provided with a circular insulating film 43, the n-contact portion 22a provided around the insulating film 43 can be formed into a circular ring shape without corners. In the n-contact portion 22a of this shape, the current density distribution can be easily uniform.

[0068] In addition, if Figure 4 As shown, by making the cross-sectional shape of the insulating film 43 into a trapezoid, it is possible to greatly ensure the interface area between the bottom (the bottom of the trapezoid) 43b of the insulating film 43 and the n-type semiconductor layer 11, and the covering property of the n-side electrode 22 on the insulating film 43 can be better than when the cross-sectional shape of the insulating film 43 is, for example, rectangular.

[0069] Fig. 9 Yes means Figure 5 A schematic top view of another arrangement pattern of elements shown.

[0070] The n-contact portion 22a is not limited to being continuous in the direction surrounding the insulating film 43, but may be in the form of a dotted line. In this case, the insulating film 43 remaining in the form of an island in the central portion of the n-side contact surface 11b is connected to a portion 42a of the insulating film 42 provided in a large area so as to cover the mesa portion 15, so that peeling of the insulating film 43 can be suppressed.

[0071] Fig.10 It is a schematic plan view of a semiconductor laminate 10 of a light emitting element according to another embodiment of the present invention.

[0072] Fig.11 FIG. 1 is a schematic enlarged cross-sectional view of a region where the n-side contact surface 11 b is provided in a light emitting element according to another embodiment.

[0073] like Fig.10 As shown, the n-side contact surface 11 b is formed in an annular shape, and in the region surrounded by the n-side contact surface 11 b , a mesa portion 15 where the light emitting layer 12 and the p-type semiconductor layer 13 are stacked is provided as a part of the semiconductor laminate 10 .

[0074] like Fig.11 As shown, the mesa portion 15 protrudes further than the n-side contact surface 11b. The insulating film 43 covers the upper surface and the side surface of the mesa portion 15. The insulating film 43 is directly provided on the side surface of the mesa portion 15. Between the insulating film 43 and the upper surface of the mesa portion 15, the insulating film 41 and the first p-side electrode 21 are provided. It should be noted that the insulating film 41 and the first p-side electrode 21 are not provided between the insulating film 43 and the upper surface of the mesa portion 15, but the insulating film 43 is directly provided on the upper surface of the mesa portion 15.

[0075] The n-side electrode 22 is provided on the insulating film 43. The n-contact portion 22a of the n-side electrode 22 is in contact with the annular n-side contact surface 11b surrounding the mesa portion 15. Fig.12 As shown, the n-side electrode 22 is not provided on the insulating film 43 surrounded by the n-side contact surface 11 b.

[0076] The insulating film 43 is provided three-dimensionally so as to cover the upper surface and the side surface of the mesa portion 15. Figure 4 The area of ​​the insulating film 43 in the region including the central portion of the n-side contact surface 11b can be increased compared to the planar insulating film 43 shown in FIG. Therefore, the light from the light emitting layer 12 that is totally reflected by the insulating film 43 in the region including the central portion of the n-side contact surface 11b can be increased.

[0077] like Fig.13 As shown in FIG. 1 , a reflective film 24 may be provided between the insulating film 43 and the mesa portion 15. The reflective film 24 preferably contains, for example, Ag, Al, or an alloy containing these metals as a main component. The insulating film 43 covers the reflective film 24 to prevent metal migration that occurs when a metal such as Ag or Al is used for the reflective film 24.

[0078] like Fig.14As shown, in the area surrounded by the n-side contact surface 11b, a portion 11d of the n-type semiconductor layer 11 that does not include the light-emitting layer 12 and the p-type semiconductor layer 13 may be provided. The portion 11d of the n-type semiconductor layer 11 protrudes further than the n-side contact surface 11b, and an insulating film 43 is directly provided on the upper surface and side surfaces of the portion 11d of the n-type semiconductor layer 11. Compared with the above-mentioned terrace portion 15, the height difference between the n-side contact surface 11b and the upper surface of the portion 11d of the n-type semiconductor layer 11 can be reduced, and the insulating film 43 can be easily formed with excellent coverage compared with a case where the height difference is large. In addition, a portion 11d of the n-type semiconductor layer 11 may be provided between the upper surface and side surfaces of the portion 11d of the n-type semiconductor layer 11 and the insulating film 43. Fig.13 The reflective film 24 is shown.

[0079] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. Based on the above-mentioned embodiments of the present invention, all the ways that can be implemented by those skilled in the art with appropriate design changes also belong to the scope of the present invention, as long as they include the gist of the present invention. In addition, within the inventive concept of the present invention, as long as various variations and modifications that can be thought of by those skilled in the art, these variations and modifications obviously also belong to the scope of the present invention.

Claims

1. A light-emitting element, comprising a semiconductor laminate, the semiconductor laminate comprising: an n-type semiconductor layer including a light extraction surface and an n-side contact surface, the n-side contact surface being provided on the opposite side of the light extraction surface and being annular in plan view; a light-emitting layer provided in a region of the n-type semiconductor layer excluding the n-side contact surface; The p-type semiconductor layer is disposed on the light-emitting layer; characterized in that: When looking down, The p-type semiconductor layer is arranged to surround the n-side contact surface. The light emitting element comprises: a mesa portion, which is a portion surrounded by the n-side contact surface and on which the light emitting layer and the p-type semiconductor layer are stacked when viewed from above; a first insulating film covering the upper surface and side surfaces of the mesa portion; a reflective film disposed between the first insulating film and the mesa portion; A p-side electrode, which is disposed on the p-type semiconductor layer and contacts the p-type semiconductor layer; a second insulating film disposed above the p-side electrode; The n-side electrode has an n-contact portion and an external connection portion, wherein the n-contact portion is provided on the first insulating film and is in surface contact with the n-side electrode; and the external connection portion is provided on the second insulating film and is connected to the n-contact portion. The p-side electrode is provided between the first insulating film and the upper surface of the mesa portion.

2. The light emitting element according to claim 1, wherein The area of ​​the n-contact portion is not less than 40% and not more than 70% of the area of ​​the n-side contact surface.

3. The light-emitting element according to claim 1 or 2, characterized in that: The second insulating film is also provided on the side surfaces of the p-type semiconductor layer, the side surfaces of the light emitting layer, the side surfaces of the n-type semiconductor layer, and the peripheral region of the n-side contact surface.

4. The light-emitting element according to claim 1 or 2, characterized in that: The first insulating film and the second insulating film are films made of the same material.

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