JP2015156431A - Semiconductor light emitting element and semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device which inhibits optical crosstalk to a large extent to achieve high performance and high luminous efficiency.

SOLUTION: A semiconductor light emitting device comprises: a semiconductor structure layer SL which includes a first semiconductor layer 21 having a first conductivity type, a luminescent layer 22 and a second semiconductor layer 23 having a second conductivity type opposite to the first conductivity type; at least one electrode 24 which pierces the second semiconductor layer 23 and the luminescent layer 22 from the second semiconductor layer 23 side to be electrically connected to the first semiconductor layer 21 and zones the semiconductor structure layer SL into a plurality of light emitting segments; and at least one light reflection groove 26 in which is formed on a surface of the first semiconductor layer 21 between adjacent light emitting segments of the plurality of light emitting segments S1, S2, S3 and has a light reflection film 27 formed on lateral faces.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting element such as a light emitting diode (LED) and a semiconductor light emitting device using the semiconductor light emitting element.

  In a semiconductor light emitting device, a semiconductor structure layer composed of an n type semiconductor layer, a light emitting layer and a p type semiconductor layer is usually grown on a growth substrate, and a voltage is applied to the n type semiconductor layer and the p type semiconductor layer, respectively. It is fabricated by forming an electrode and a p-electrode. Further, as a semiconductor light emitting device for improving heat dissipation performance, a semiconductor light emitting device is known in which a semiconductor structure layer is bonded to a support substrate different from a growth substrate and then the growth substrate is removed. Further, for example, the semiconductor light emitting device is manufactured by fixing the semiconductor light emitting element on a mounting substrate and sealing it with a resin or the like.

  Patent Document 1 discloses an LED array chip having an LED array composed of a plurality of LEDs formed by crystal growth on a substrate. Patent Document 2 discloses a light-emitting device including a plurality of first trenches that divide a plurality of light-emitting elements, and a plurality of second trenches that pass through active layers of the plurality of light-emitting elements, and a method for manufacturing the same. ing. Further, in Patent Document 3, a first semiconductor layer, a second semiconductor layer, a semiconductor film including an active layer provided between the first semiconductor layer and the second semiconductor layer, and the first semiconductor layer are provided in the first semiconductor layer. A semiconductor light emitting device including a current induction portion is disclosed.

JP 2005-73202 A JP 2012-60115 A JP 2012-151415 A

  2. Description of the Related Art In recent years, attention has been paid to a technology for controlling a light distribution shape in real time according to the situation ahead, that is, the presence or absence of an oncoming vehicle or a preceding vehicle, and the position thereof. With this technology, for example, when an oncoming vehicle is detected while traveling with a light distribution shape, that is, a high beam, only the area of the oncoming vehicle among the areas irradiated on the headlight can be shielded in real time. It becomes possible. Therefore, it is possible to always give the driver a field of view close to a high beam, while preventing the oncoming vehicle from being dazzled (glare). Such a light distribution variable headlight system, for example, manufactures a semiconductor light emitting device in which a plurality of semiconductor light emitting elements are arranged in an array, and controls conduction and non-conduction to each of the semiconductor light emitting elements in real time. Can be realized.

  However, in general, in a semiconductor light emitting device in which a plurality of semiconductor light emitting elements are juxtaposed, part of light emitted from a conductive element may propagate to a non-conductive element. In this case, a weak light is emitted from the non-conducting element, and there is a case where light is irradiated to an unintended region. This problem of so-called light crosstalk further causes the problem that the boundary between the irradiation region and the non-irradiation region of the light emitting device is obscured and a desired light distribution shape cannot be obtained. In various application fields of light emitting devices using a plurality of elements, it is desirable that there is no crosstalk of light.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a semiconductor light emitting device with high performance and high light emission efficiency in which crosstalk of light to the outside of the element region is greatly suppressed.

  A semiconductor light emitting device according to the present invention includes a first semiconductor layer having a first conductivity type, a light emitting layer, and a second semiconductor layer having a second conductivity type opposite to the first conductivity type. And at least one first structure layer that is electrically connected to the first semiconductor layer through the second semiconductor layer and the light emitting layer from the second semiconductor layer side, and partitions the semiconductor structural layer into a plurality of light emitting segments. And at least one light reflection groove formed on the surface of the first semiconductor layer between the one electrode and the adjacent light emission segments of the plurality of light emission segments and having a light reflection film formed on the side surface. It is a feature.

(A) is sectional drawing which shows the structure of the semiconductor light-emitting device concerning Example 1, (b) is a figure which shows the upper surface of the semiconductor light-emitting device concerning Example 1 typically. FIG. 4 is a diagram illustrating a light path in an element in the semiconductor light emitting device of Example 1. (A) And (b) is sectional drawing which shows the detail of the light reflection groove | channel of the semiconductor light-emitting device which concerns on the modification 1 and the modification 2 of Example 1, respectively. 7 is a cross-sectional view illustrating a structure of a semiconductor light emitting device according to Modification 3 of Example 1. FIG.

  Examples of the present invention will be described in detail below.

FIG. 1A is a cross-sectional view showing the structure of the semiconductor light emitting device 10 of the first embodiment. The semiconductor light emitting device 10 includes a semiconductor light emitting element 20 and a mounting portion 30 on which the semiconductor light emitting element 20 is mounted. The semiconductor light emitting device 20 includes an n-type (first conductivity type) semiconductor layer (first semiconductor layer) 21, a light-emitting layer 22, and a p-type (second conductivity type opposite to the n-type) semiconductor. The semiconductor structure layer SL including the layer (second semiconductor layer) 23 is included. The semiconductor light emitting device 10 has a structure in which a p-type semiconductor layer 23, a light emitting layer 22, and an n-type semiconductor layer 21 are sequentially stacked on the mounting portion 30 in this order. The n-type semiconductor layer 21, the light emitting layer 22, and the p-type semiconductor layer 23 have a composition of, for example, Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). The surface of the n-type semiconductor layer 21 has an uneven surface structure composed of a plurality of protrusions 21P, and this uneven surface functions as a light extraction surface.

  The semiconductor light emitting device 20 includes a plurality of n electrodes (first electrodes) 24 </ b> A that penetrate the p type semiconductor layer 23 and the light emitting layer 22 from the p type semiconductor layer 23 side and are electrically connected to the n type semiconductor layer 21. An n electrode group (first electrode group) 24 made of 24B is provided. Each of the n electrodes 24A and 24B of the n electrode group 24 is configured to partition the light emitting layer 22 and the p-type semiconductor layer 23 of the semiconductor structure layer SL into a plurality of light emitting segments S1, S2, and S3. Here, the light-emitting layer 22A and the p-type semiconductor layer 23A are referred to as a light-emitting segment S1, and similarly, the light-emitting layer 22B and the p-type semiconductor layer 23B, and the light-emitting layer 22C and the p-type semiconductor layer 23C are referred to as light-emitting segments S2 and S3, respectively. The n electrodes 24A and 24B are made of a metal material such as Ti, Al, Pt, Au, and Ag.

  Further, in each of the light emitting segments S1 to S3, a p electrode group (second electrode group) 25 including p electrodes (second electrodes) 25A to 25C is formed on each of the p-type semiconductor layers 23A to 23C. Has been. Each of the p electrodes 25A to 25C of the p electrode group 25 includes, for example, a transparent electrode layer M1 formed on the p-type semiconductor layer 23A, a reflective metal layer M2 formed to cover the transparent electrode layer M1, and a reflective And a cap layer M3 formed so as to embed the metal layer M2. The transparent electrode layer M1 is made of a conductive material having translucency such as ITO or IZO. The reflective metal layer M2 is made of a material having light reflectivity, such as Ag, Pt, Ni, Al, Pd, and alloys thereof. The transparent electrode layer M1 and the reflective metal layer M2 have a function of reflecting light emitted from the light emitting layer 22A toward the light extraction surface. The cap layer M3 is a layer that prevents migration of the material of the reflective metal layer M2, and can be formed using, for example, Ti, W, Pt, Pd, Mo, Ru, Ir, Au, or alloys thereof.

The semiconductor light emitting element 20 has a light reflecting groove 26 formed on the surface of the n-type semiconductor layer 21 between the light emitting segment S2 adjacent to the light emitting segment S1, and a light reflecting film 27 on the side surface of the light reflecting groove 26. Is formed. The light reflecting film 27 is made of an insulating material such as SiO ₂ or SiN. Each of the light reflection grooves 26 is formed over the entire area between the light emitting segments. The light reflecting groove 26 has a function of preventing light emitted from the light emitting layer 21A of the light emitting segment S1 from leaking to the light emitting segment S2 which is another adjacent light emitting segment, that is, crosstalk. The light reflecting film 27 may be provided not only on the side surface of the light reflecting groove 26 but also on the entire inner wall surface of the light reflecting groove 26, or may be filled in the light reflecting groove 26.

  The light reflection grooves 26 are provided on both sides of the n-electrode 24A when viewed from a direction perpendicular to the semiconductor structure layer SL (that is, in a top view). The light reflecting groove 26 is formed from the surface of the n-type semiconductor layer 21 to a depth exceeding the bottom of the n-electrode 24A. Since the light reflecting grooves 26 are formed on both sides of the n electrode 24A and to a depth exceeding the bottom of the n electrode 24A, crosstalk of light between the light emitting segments can be significantly suppressed. The n-electrode group 24 and the p-electrode group 25 are insulated by 28 with an insulating protective film.

  The semiconductor light emitting element 20 is mounted on the mounting portion 30. The mounting unit 30 is provided on the mounting substrate 31, an n-side wiring group (first wiring group) 32 including a plurality of n-side wirings (first wirings) 32A and 32B, and the mounting substrate. And a p-side wiring group (second wiring group) 33 including a plurality of p-side wirings (second wirings) 33A to 33C. The n-side wirings 32A and 32B are connected to the n-electrodes 23A and 24B, respectively, and the p-side wirings 33A to 33C are connected to the p-electrodes 25A to 25C, respectively. The n-side wiring group 32 and the p-side wiring group 33 are formed on the mounting substrate 31 so as to be separated from each other.

  The mounting substrate 31 is made of a material having high thermal conductivity, such as Si, AlN, Mo, W, or CuW. An insulating layer (not shown) is formed on the mounting substrate 31. The n-side wiring group 32 and the p-side wiring group 33, and the n-electrode group 24 and the p-electrode group are made of Au and Sn, Au and In, Pd and In, Cu and Sn, respectively. , Ag and Sn, Ag and In, and Ni and Sn, or a combination of materials that are fused and joined together, or a material that is diffused and joined together such as Au.

  Next, a method for manufacturing the semiconductor light emitting device 10 will be described. In this example, first, a semiconductor structure layer SL was formed on a growth substrate (not shown), and then a metal layer to be the p electrode group 25 was formed. Subsequently, a part of the metal layer was removed, and a through groove reaching the n-type semiconductor layer 21 through the p-type semiconductor layer 23 and the light emitting layer 22 was formed on the exposed surface of the p-type semiconductor layer 23. Next, an insulating film was formed so as to cover the entire p electrode group 25 and the through groove. Thereafter, the bottom of the through groove and a part of the insulating film on the p-type semiconductor layer were removed to form an n electrode group 24 and a p electrode group 25. Next, after mounting substrate 31 was prepared and an insulating layer was formed on mounting substrate 31, n-side wiring group 32 and p-side wiring group 33 were formed. Subsequently, the n-electrode group 24 and the n-side wiring group 32 were joined, and the p-electrode group 25 and the p-side wiring group 33 were joined. Thereafter, the growth substrate was removed, a light reflection groove and a light reflection film were formed on the exposed surface of the n-type semiconductor layer 21, and a plurality of protrusions 21P were further formed to manufacture the semiconductor light emitting device 20. Although not shown, a phosphor layer is formed on the mounting substrate 31 so as to embed the semiconductor light emitting element 20, and the semiconductor light emitting device 10 is manufactured by mounting the phosphor layer on the mounting substrate.

  In this embodiment, the n-side wirings 32A and 32B are electrically connected, and each of the p-side wirings 33A to 33C is electrically separated. Accordingly, the light emitting segments are connected in parallel. Further, with such a wiring structure, each of the light emitting segments S1 to S3 emits light independently of each other by controlling conduction and non-conduction to the p-side wirings 33A to 33C.

  FIG. 1B is a diagram schematically showing the upper surface of the semiconductor light emitting device 10. 1A is a cross-sectional view taken along the line VV in FIG. For ease of understanding, FIG. 1B shows each light emitting segment, the n electrode group 24, and the light reflecting groove 26, and the n electrode group 24 is hatched. In the present embodiment, the semiconductor light emitting element 20 has nine light emitting segments S1 to S9, and forms a rectangular light emitting portion as a whole. Specifically, the n-electrode group 24 includes four n-electrodes 24A to 24D formed in a lattice shape as a whole when viewed from a direction perpendicular to the semiconductor structure layer SL. Each of the n electrodes 24A to 24D is provided in a straight line shape, and the semiconductor structure layer SL is partitioned into nine rectangular light emitting segments by the n electrode group 24. In addition, a plurality of light-emitting segments are provided in a matrix in a top view. Each of the four n-electrodes 24A to 24D is connected at the intersection and functions as one common n-electrode.

  Next, the path of light in the semiconductor light emitting element 20 of the semiconductor light emitting device 10 will be described with reference to FIG. FIG. 2 is a cross-sectional view similar to FIG. 1A, but some hatching is omitted. Here, the light that may cause crosstalk is mainly light that travels in a direction close to a direction parallel to the light emitting layer 22 from the light emitting segment. Here, the path of such light in the semiconductor light emitting device 20 will be described with reference to FIG. Note that other light, that is, light emitted from the light emitting segment toward the light extraction surface passes through the uneven surface of the light extraction surface and is extracted outside.

  First, the light L1 emitted from the light emitting segment S1 toward the light reflecting groove 26 is reflected by the light reflecting film 27 of the light reflecting groove 26 and is taken out from the light extraction surface on the light emitting segment S1. Therefore, the light emitted from the light emitting segment S1 is prevented from leaking to the region on the adjacent light emitting segment S2.

  Next, the light L2 emitted from the light emitting segment S1 toward the region between the n electrode 24A and the light reflecting groove 26 in the n-type semiconductor layer 21 is reflected by the n electrode 24A, and the light emitting segments S1 and S2 It is taken out outside. This is because the n electrode group 24 has reflectivity and thus functions as a layer that prevents crosstalk, and the n electrode 24A does not penetrate the n-type semiconductor layer 21.

  In this embodiment, the n-electrode 24A does not completely penetrate the n-type semiconductor layer 21, and the n-type semiconductor layer 21 of the semiconductor light emitting element 20 is not completely separated between the light emitting segments. That is, a part of the n-type semiconductor layer 21 is formed on the region between the light reflection grooves 26, that is, on the n electrode 24 </ b> A (on the n electrode group 24). Accordingly, a part of light passing through the region in the n-type semiconductor layer 21 between the light reflection groove 26 and the n electrode 24A, that is, light such as the light L2 is extracted from the light extraction surface between the light reflection grooves 26. It becomes.

  Note that when a light-emitting device is configured by a plurality of light-emitting segments, a region that does not emit light is formed between the light-emitting segments. Therefore, for example, even when all the light emitting segments are caused to emit light, a slight dark portion (dark line) is formed in the irradiated image. Therefore, in order to suppress the formation of this dark part, it is preferable that the distance between the light emitting segments is small.

  In contrast, in this embodiment, the n-type semiconductor layer 21 is first formed also on the n-electrode group 24, and the n-electrode group 24 functions as an n-electrode common to each light-emitting segment. Therefore, the distance between the light emitting regions can be reduced as compared with the case where the n-type semiconductor layer is separated into a plurality of light emitting elements and the plurality of light emitting elements are juxtaposed on the mounting substrate. Specifically, when a plurality of light emitting elements are juxtaposed on the mounting substrate, a certain amount of gap needs to be provided between the elements in order to drive the light emitting elements independently. However, in this embodiment, it is only necessary to provide a region for forming the n electrode group, so that the distance between the light emitting regions is reduced.

  Further, as described above, since the light can be extracted from between the light emitting segments as in the case of the light L2, the formation of a dark portion corresponding to the region between the light emitting segments can be suppressed. In consideration of further improving the crosstalk prevention effect and the light extraction efficiency, each n electrode forming surface of the n electrode group 24 has a tapered shape toward the n-type semiconductor layer 21 as illustrated. It is desirable that

  Furthermore, in this embodiment, the semiconductor structure layer SL is partitioned into light emitting segments by the n electrode group 24. Therefore, compared to the case where the n-electrode is formed in the region on the light emitting segment, there is no metal layer or the like that obstructs the light path, and it becomes unnecessary to remove the light emitting layer in the light emitting segment. Therefore, it is possible to suppress the formation of dark portions even in the light emitting segment.

FIGS. 3A and 3B are cross-sectional views illustrating details of the light reflecting grooves of the semiconductor light emitting device according to the first and second modifications of the first embodiment, respectively. As shown in FIG. 3A, an optical multilayer film structure including a first light reflection film RL1 and a second light reflection film RL2 is formed on the side surface of the light reflection groove 26 of the semiconductor light emitting device according to Modification 1. A light reflection film 27A is formed. The first light reflecting film RL1 is made of an insulating material such as SiO ₂ . The second light reflection film RL2 is made of an oxide film such as TiO ₂ . That is, in this modification, the light reflecting film 27A is an optical multilayer film in which a plurality of films having different refractive indexes are stacked. Therefore, the reflectance of light becomes higher and crosstalk is greatly suppressed.

  In FIG. 3B, in the semiconductor light emitting device according to the second modification of the first embodiment, a light reflecting film 26 is formed on the inner wall of the light reflecting groove 26, and a light absorbing film 29 is formed on the light reflecting film 26. Is formed. The light absorption film 29 is made of a material that absorbs light emitted from the light emitting layer, such as Ti, Rh, Pt, Al, Ag, Au, and the like. In this modification, not only the light reflection film 26 but also a light absorption film 29 is formed in the light reflection groove 26. Accordingly, for example, stray light that has been once emitted from the light extraction surface and returned to the n-type semiconductor layer 21 via a phosphor layer (not shown) or a sealing material (not shown) is a light absorbing film. 29 absorbs and attenuates. Therefore, crosstalk is further suppressed. The light absorption film 29 may have a single layer structure or a multilayer structure.

  In this embodiment, the first conductivity type (or conductivity polarity) is an n-type conductivity type, and the second conductivity type is a p-type conductivity type opposite to the n-type. However, the first conductivity type may be p-type and the second conductivity type may be n-type. Further, either the first conductivity type or the second conductivity type may be an intrinsic conductivity type. That is, either the first semiconductor layer or the second semiconductor layer may be an intrinsic semiconductor layer (i layer). Moreover, although the case where the surface of the semiconductor structure layer that is the light extraction surface is an uneven structure surface including a plurality of protrusions has been described, the surface of the semiconductor structure layer may be flat. Moreover, although the case where each light emission segment was connected in parallel was demonstrated, each light emission segment may be mutually connected in series, and may mutually be isolate | separated electrically.

  Further, although the case where the light reflecting groove is formed so as to sandwich the n electrode has been described, if the light reflecting groove is formed between the light emitting segments, a certain crosstalk preventing effect can be obtained. For example, as shown in FIG. 4, the light reflection groove may be formed at a position facing each of the n electrodes 24A and 24B on the surface of the n-type semiconductor layer 21 (light reflection groove 26A, Modification 3). . Moreover, although the case where the light reflection groove is formed with a depth exceeding the bottom of the n electrode has been described, the depth of the light reflection groove is not limited to this.

  Moreover, although the case where the n electrode group is composed of a plurality of n electrodes has been described, the n electrode group may be composed of at least one n electrode. That is, at least one n-electrode that penetrates the p-type semiconductor layer and the light-emitting layer from the p-type semiconductor layer side and is electrically connected to the n-type semiconductor layer and partitions the semiconductor structure layer into a plurality of light-emitting segments is formed. Just do it. Further, the number of light reflecting grooves can be determined as appropriate, for example, corresponding to the number of n electrodes.

  In the divided light emitting segment, the light reflecting groove and the light reflecting film may or may not be formed in a portion of the outermost light emitting segment that is not adjacent to another light emitting segment. The outermost part is a part corresponding to the outer edge of the light emitting part. For example, in applications where it is required to clarify the outline of the irradiation image of the apparatus, a light reflecting groove and a light reflecting film are formed. Is desirable.

  In the present embodiment, at least one partitioning the semiconductor structure layer into a plurality of light-emitting segments through the second semiconductor layer and the light-emitting layer and electrically connected to the first semiconductor layer on the second semiconductor layer. And at least one light reflecting groove formed on the surface of the first semiconductor layer between the first light emitting segments and adjacent light emitting segments of the plurality of light emitting segments and having a light reflecting film formed on a side surface. doing. Therefore, the light emitted from the light emitting segment of the semiconductor light emitting element is largely suppressed from being emitted to the outside from a region other than its own light extraction surface. Accordingly, it is possible to provide a semiconductor light emitting element and a semiconductor light emitting device in which crosstalk of light is greatly suppressed.

DESCRIPTION OF SYMBOLS 10 Semiconductor light-emitting device 20 Semiconductor light-emitting device 21 N type semiconductor layer (1st semiconductor layer)
22 Light emitting layer 23 p-type semiconductor layer (second semiconductor layer)
S1, S2, S3, S9 Light emitting segments 24A, 24B, 24C n electrode (first electrode)
25A, 25B, 25C p-electrode (second electrode)
26 light reflection groove 27 light reflection film 29 light absorption film 31 mounting substrate 32A, 32B, 32C n-side wiring (first wiring)
33A, 33B, 33C p-side wiring (second wiring)

Claims (8)

A semiconductor structure layer including a first semiconductor layer having a first conductivity type, a light emitting layer, and a second semiconductor layer having a second conductivity type opposite to the first conductivity type;
At least one that penetrates the second semiconductor layer and the light emitting layer from the second semiconductor layer side and is electrically connected to the first semiconductor layer, and divides the semiconductor structure layer into a plurality of light emitting segments. A first electrode;
And at least one light reflecting groove formed on a surface of the first semiconductor layer between the light emitting segments adjacent to the plurality of light emitting segments, and having a light reflecting film formed on a side surface thereof. A semiconductor light emitting device.   2. The semiconductor light emitting element according to claim 1, wherein the light reflection grooves are provided on both sides of the first electrode when viewed from a direction perpendicular to the light emitting layer.   3. The semiconductor light emitting element according to claim 2, wherein the light reflecting groove is formed from a surface of the first semiconductor layer to a depth exceeding a bottom portion of the first electrode.   The semiconductor light emitting element according to claim 1, wherein the light reflection groove is formed at a position facing the first electrode.   5. The semiconductor light emitting element according to claim 1, wherein the light reflecting film is made of an insulating material.   6. The semiconductor light emitting element according to claim 1, wherein the light reflecting film is an optical multilayer film in which a plurality of films having different refractive indexes are stacked.   The semiconductor light emitting element according to claim 1, wherein a light absorption film is formed on the light reflection film. A semiconductor light emitting device according to any one of claims 1 to 7,
A second electrode, each formed on the second semiconductor layer in each of the plurality of light emitting segments;
A mounting substrate;
A first wiring provided on the mounting substrate and connected to the at least one first electrode;
A semiconductor light emitting device comprising: a plurality of second wirings provided on the mounting substrate, connected to each of the second electrodes, and electrically isolated from each other.

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