WO2017038447A1

WO2017038447A1 - Nitride surface-emitting laser

Info

Publication number: WO2017038447A1
Application number: PCT/JP2016/073882
Authority: WO
Inventors: 将一郎泉; 達史濱口; 統之風田川; 大倉本
Original assignee: ソニー株式会社
Priority date: 2015-09-02
Filing date: 2016-08-16
Publication date: 2017-03-09
Also published as: JPWO2017038447A1; JP6973077B2

Abstract

A first nitride surface-emitting laser comprising: a first dielectric multilayer film and a second dielectric multilayer film that are provided upon a substrate and are adjacent to each other; a current injection region provided at a position facing the first dielectric multilayer film; and an opening provided between the first dielectric multilayer film and the second dielectric multilayer film. When the distance between the first dielectric multilayer film and the second dielectric multilayer film is W and the thickness of the first dielectric multilayer film in the normal direction relative to the substrate is H, the first dielectric multilayer film, the opening, and the current injection region are formed such that an angle θ is at least arctan (H/W) and no more than 90°, said angle θ being between the upper surface of the first dielectric multilayer film and a line connecting, by the shortest distance, an end edge of the upper surface of the first dielectric multilayer film and an end edge of the current injection region.

Description

Nitride surface emitting laser

The present technology relates to, for example, a nitride surface emitting laser that emits laser light in the stacking direction.

A surface emitting laser is generally provided with light reflecting layers (Distributed Bragg Reflector layers; DBR layers) above and below a semiconductor layer including an active layer. In the surface emitting laser, laser oscillation occurs by resonating light between the two DBR layers. For this reason, it is necessary to smooth the semiconductor surface on which the DBR layer is formed on the sub-nanometer order. If an appropriate smoothness cannot be obtained, the light reflectivity of each DBR layer is reduced, and variations in characteristics (e.g., oscillation threshold) are increased, and it is difficult to obtain laser oscillation. Control of the resonator length is also important. The resonator length also needs to be controlled in the order of nanometers. If the resonator length deviates from the design value, sufficient gain cannot be obtained, and it becomes difficult to obtain laser oscillation.

For this problem, for example, Patent Document 1 proposes a method of embedding a multilayer dielectric layer that can function as a DBR layer in a semiconductor layer by using a selective growth method. In this method, there is an alignment step for forming a light extraction portion on the multilayer dielectric layer that becomes the DBR layer. For this reason, in consideration of alignment variations, a multilayer dielectric layer larger than the light extraction portion is formed and embedded.

JP-A-10-308558

However, when a large-diameter multilayer dielectric layer is embedded, it becomes difficult to inspect device characteristics and repair defects in the electrodes. For this reason, it is difficult to improve the reliability, and the manufacturing yield is reduced.

Therefore, it is desirable to provide a nitride surface emitting laser capable of improving reliability and manufacturing yield.

A first nitride surface-emitting laser according to an embodiment of the present technology is provided on a substrate and faces a first dielectric multilayer film and a second dielectric multilayer film that are adjacent to each other, and the first dielectric multilayer film. A current injection region provided at a position, and an opening provided between the first dielectric multilayer film and the second dielectric multilayer film. When the distance between the first dielectric multilayer film and the second dielectric multilayer film is W and the thickness of the first dielectric multilayer film in the normal direction to the substrate is H, the first dielectric multilayer film, the opening And the current injection region has an angle θ between the line segment connecting the edge of the upper surface of the first dielectric multilayer film and the edge of the current injection region with the shortest distance and the upper surface of the first dielectric multilayer film, It is formed to be arctan (H / W) or more and 90 ° or less.

In a first nitride surface emitting laser according to an embodiment of the present technology, a line segment connecting the edge of the upper surface of the first dielectric multilayer film and the edge of the current injection region with the shortest distance, and the first dielectric The angle θ formed with the upper surface of the multilayer film was set to arctan (H / W) or more and 90 ° or less. Thereby, it is possible to irradiate the current injection region and the vicinity thereof with laser light and excitation light without being blocked by the first dielectric multilayer film from the substrate side.

A second nitride surface emitting laser according to an embodiment of the present technology is provided on a substrate and faces a first dielectric multilayer film and a second dielectric multilayer film that are adjacent to each other, and the first dielectric multilayer film. A current injection region provided at a position, and an opening provided between the first dielectric multilayer film and the second dielectric multilayer film. The distance between the first dielectric multilayer film and the second dielectric multilayer film is W, the opening is from the intersection of the perpendicular drawn from the outer edge of the upper surface of the first dielectric multilayer film and the bottom of the first dielectric multilayer film And the thickness of the first dielectric multilayer film in the normal direction relative to the substrate is H, the first dielectric multilayer film, the opening and the current injection region are the upper surface of the first dielectric multilayer film. An angle θ formed by a line segment connecting the edge of each of the current injection regions with the edge of the current injection region and the upper surface of the first dielectric multilayer film is arctan (H / (W + W ′)) or more and 90 ° or less. It is formed to become.

In the second nitride surface emitting laser according to an embodiment of the present technology, a line segment connecting the edge of the upper surface of the first dielectric multilayer film and the edge of the current injection region with the shortest distance, and the first dielectric The angle θ formed with the upper surface of the multilayer film was set to arctan (H / (W + W ′)) or more and 90 ° or less. Thereby, it is possible to irradiate the current injection region and the vicinity thereof with laser light and excitation light without being blocked by the first dielectric multilayer film from the substrate side.

According to the first nitride surface emitting laser of the first embodiment of the present technology and the second nitride surface emitting laser of the embodiment, the first dielectric semiconductor film, the opening, and the current injection region are formed in the first nitride semiconductor laser. In the second nitride surface emitting laser, the angle θ is not less than arctan (H / (W + W ′)) and not more than 90 ° so that the angle θ is not less than arctan (H / W) and not more than 90 °. Therefore, it is possible to irradiate the current injection region and the vicinity thereof with laser light and excitation light without being blocked by the first dielectric multilayer film from the substrate side. Therefore, the reliability and manufacturing yield of the nitride surface emitting laser can be improved. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

1 is a cross-sectional view of a surface emitting semiconductor laser according to a first embodiment of the present technology. FIG. 2 is an enlarged schematic view for explaining a main part of the semiconductor laser shown in FIG. 1. It is a schematic diagram showing the planar shape of the dielectric multilayer film of the semiconductor laser shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the semiconductor laser shown in FIG. It is sectional drawing for demonstrating the process following FIG. 4A. It is sectional drawing for demonstrating the process following FIG. 4B. It is a schematic diagram for demonstrating the device characteristic test | inspection in the semiconductor laser shown in FIG. It is a schematic diagram for demonstrating the defect repair in the semiconductor laser shown in FIG. It is sectional drawing of the surface emitting semiconductor laser which concerns on the 2nd Embodiment of this technique. FIG. 8 is an enlarged schematic diagram for explaining a main part of the semiconductor laser shown in FIG. 7. FIG. 8 is a schematic diagram showing another shape of the dielectric multilayer film of the semiconductor laser shown in FIG. 7. It is a schematic diagram for demonstrating the device characteristic test | inspection in the semiconductor laser shown in FIG. FIG. 8 is a schematic diagram for explaining defect repair in the semiconductor laser shown in FIG. 7.

Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The description will be given in the following order.
1. First embodiment (semiconductor laser in which the dielectric multilayer film on the substrate side has a rectangular cross section)
1-1. Overall configuration 1-2. Manufacturing method 1-3. Action / Effect Second Embodiment (Semiconductor Laser with Dielectric Multilayered Film on the Substrate Side has a Forward Tapered Shape)
2-1. Main part configuration 2-2. Action / Effect

<1. First Embodiment>
FIG. 1 shows an example of a cross-sectional configuration of a nitride surface emitting laser (semiconductor laser 1) according to the first embodiment of the present technology. The semiconductor laser 1 includes a substrate 11 and a plurality of dielectric multilayer films 41 in contact with the surface S1 of the substrate 11. The plurality of dielectric multilayer films 41 are provided on the substrate 11 at intervals. The semiconductor laser 1 further has a configuration in which the semiconductor layer 20, the insulating film 24, the transparent electrode 32, the second electrode 33, and the second DBR layer 42 are stacked in this order. If the dielectric multilayer film 41 facing the second DBR layer 42 among the plurality of dielectric multilayer films 41 is the first DBR layer 41A, the pair of first DBR layer 41A and second DBR layer 42 function as a resonator. The semiconductor layer 20 has a configuration in which a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 are stacked in this order from the substrate 11 side. Each dielectric multilayer film 41 is buried with the first semiconductor layer 21. Between the first DBR layer 41A and the dielectric multilayer film 41 adjacent to the first DBR layer 41A, a groove-shaped opening 41H is formed. Is formed. An angle between a line segment connecting the edge of the upper surface of the first DBR layer 41A and the edge of the current injection region R with the shortest distance and the upper surface of the first DBR layer 41A is within a predetermined range. The semiconductor laser 1 has a first electrode 31 in contact with the surface S2 of the substrate 11 (the surface facing the surface S1). Note that the semiconductor laser 1 in FIG. 1 is schematically shown and is different from actual dimensions.

(1-1. Overall configuration)
The substrate 11 is an element forming substrate used for manufacturing the semiconductor layer 20. The substrate 11 is provided in contact with the semiconductor layer 20 (first semiconductor layer 21). As the substrate 11, for example, various substrates such as a GaN substrate, a sapphire substrate, a GaAs substrate, a SiC substrate, an alumina substrate, a ZnS substrate, a ZnO substrate, a LiMgO substrate, a LiGaO ₂ substrate, a MgAl ₂ O ₄ substrate, and an InP substrate are used. it can. In addition, an insulating substrate made of AlN or the like, a semiconductor substrate made of Si, SiC, Ge, or the like, a metal substrate, or an alloy substrate may be used. The thickness of the substrate 11 in the stacking direction (hereinafter simply referred to as thickness) is preferably 0.05 mm to 0.5 mm, for example.

The semiconductor layer 20 has a configuration in which a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 are sequentially stacked from the substrate 11 side. The first semiconductor layer 21 and the second semiconductor layer 23 have different conductivity types. For example, the first semiconductor layer 21 is formed of an n-type compound semiconductor, and the second semiconductor layer 23 is formed of a p-type compound semiconductor. Is formed. The first semiconductor layer 21, the active layer 22, and the second semiconductor layer 23 are each composed of a nitride-based compound semiconductor. Specific nitride compound semiconductors include GaN compound semiconductors such as GaN, AlGaN, InGaN, and AlInGaN. In addition, AlN, AlInN, and InN are mentioned. Furthermore, these compound semiconductors may contain boron (B) atoms, thallium (Tl) atoms, arsenic (As) atoms, phosphorus (P) atoms, and antimony (Sb) atoms as desired. . The active layer 22 preferably has a quantum well structure. Specifically, it may have a single quantum well structure (QW structure) or a multiple quantum well structure (MQW structure). The active layer 22 having a quantum well structure has a structure in which at least one well layer and a barrier layer are stacked. As a combination of (a compound semiconductor constituting a well layer and a compound semiconductor constituting a barrier layer), (In _y Ga _(1-y) N, GaN), (In _y Ga _(1-y) N, In _z Ga _(1-z) N) [where y> z], (In _y Ga _{(1- y)} N, AlGaN), (AlGaN / GaN), (AlzGa1 _- zN / AlyGa1 _-yN ) [where y> z].

The first semiconductor layer 21 and the second semiconductor layer 23 may each be a single structure layer or a multilayer structure layer. Further, it may be a layer having a superlattice structure. Furthermore, it can also be set as the layer provided with the composition gradient layer and the density | concentration gradient layer.

A current confinement structure is formed between the semiconductor layer 20 (specifically, the second semiconductor layer 23) and the second electrode 33. The current confinement structure is configured by an insulating film 24 provided on the second semiconductor layer 23, for example. The insulating film 24 has an opening 24A from which the second semiconductor layer 23 is exposed, and this opening serves as a current injection region R in the semiconductor layer 20 (second semiconductor layer 23). At this time, the current injection region R in the semiconductor layer 20 (second semiconductor layer 23) corresponds to the emission window 24W that emits light emitted from the active layer 22. The insulating film 24 is made of, for example, SiO _x , SiN _x or AlO _x .

Note that the current confinement structure is not necessarily formed by the insulating film 24. For example, the mesa structure may be formed by etching the second semiconductor layer 23 by a reactive ion etching (RIE) method or the like, or a part of the stacked second semiconductor layers 23. May be partially oxidized from the lateral direction to form a current injection region. Furthermore, impurities may be ion-implanted into the second semiconductor layer 23 to form a region with reduced conductivity, and these may be combined as appropriate. However, the transparent electrode 32 is provided on the second semiconductor layer 23, and the transparent electrode 32 needs to be electrically connected to a part of the second semiconductor layer 23 through which a current flows.

The first electrode 31 is provided on the surface S2 opposite to the surface S1 of the substrate 11 on which the semiconductor layer 20 is formed. The first electrode 31 includes, for example, gold (Au), silver (Ag), palladium (Pd), platinum (Pt), nickel (Ni), Ti (titanium), vanadium (V), tungsten (W), chromium ( It is a single layer film or a laminated film containing at least one kind of metal (including an alloy) of Cr), Al (aluminum), Cu (copper), Zn (zinc), tin (Sn), and indium (In). It is preferable. Specifically, for example, Ti / Au, Ti / Al, Ti / Al / Au, Ti / Pt / Au, Ni / Au, Ni / Au / Pt, Ni / Pt, Pd / Pt, Ag / Pd, etc. A laminated film is mentioned. Note that the layer before the “/” in the multilayer structure is located closer to the active layer 22 side.

The transparent electrode 32 is provided on the semiconductor layer 20, specifically, on the second semiconductor layer 23. The transparent electrode 32 is provided in contact with the emission window 24 </ b> W in the second semiconductor layer 23. The transparent electrode 32 is formed of a so-called transparent conductive material having optical transparency. Specific transparent conductive materials include, for example, indium-tin oxide (including ITO, Indium Tin Oxide, Sn-doped In ₂ O ₃ , crystalline ITO, and amorphous ITO), indium-zinc oxide (IZO, Indium zinc oxide), IFO (F-doped in ₂ O _3), tin oxide (SnO _2), ATO (Sb-doped SnO _2), FTO (F doped SnO _2), zinc oxide (ZnO, ZnO of Al-doped And B-doped ZnO). In addition, a transparent conductive film whose base layer is gallium oxide, titanium oxide, niobium oxide, nickel oxide, or the like may be used. However, although the material which comprises the transparent electrode 32 is based on the arrangement state of the 2nd DBR layer 42 and the transparent electrode 32 mentioned later, it is not limited to a transparent conductive material, Palladium (Pd), platinum (Pt), nickel Metals such as (Ni), gold (Au), cobalt (Co), rhodium (Rh) can also be used. The transparent electrode 32 may be composed of at least one of these materials.

The second electrode 33 is provided on the transparent electrode 32 and is used for electrical connection with an external electrode or circuit. The second electrode 33 is, for example, a single layer film containing at least one metal selected from Ti (titanium), aluminum (Al), Pt (platinum), Au (gold), Ni (nickel), and Pd (palladium). Or it is preferable that it is a laminated film. Specifically, for example, a laminated film of Ti / Pt / Au, Ti / Au, Ti / Pd / Au, Ti / Pd / Au, Ti / Ni / Au, Ti / Ni / Au / Cr / Au, etc. It is done.

A plurality of dielectric multilayer films 41 are provided in the plane of the substrate 11 and are embedded with the first semiconductor layer 21. A groove-shaped opening 41 </ b> H is provided between adjacent dielectric multilayer films 41, and the opening 41 </ b> H is embedded by the first semiconductor layer 21. The dielectric multilayer film 41 includes, for example, Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Ti, and other oxides and nitrides (for example, SiN _x , AlN _x , AlGaN, GaN _x , BN _x, etc.) or fluoride. _{_{Specifically, SiO x, TiO x, NbO}} x, ZrO x, TaO x, ZnO x, AlO x, HfO x, SiN x, AlN x , and the like. The first DBR layer 41A includes two or more kinds of dielectric films made of dielectric materials having different refractive indexes among the dielectric materials (for example, TaO _x having a high refractive index and SiO _x having a low refractive index). It is preferable that the layers are alternately stacked. Thereby, the light reflection effect is obtained. Examples of combinations of the two types of dielectric films include SiO _x / SiN _x , SiO _x / NbO _x , SiO _x / ZrO _x , SiO _x / AlN _x in addition to SiO _x / TaO _x . In order to obtain a desired light reflectance, the material, the film thickness, the number of stacked layers, and the like constituting each dielectric film may be appropriately selected. For example, the dielectric multilayer film 41 is preferably arranged or arranged so as to grow laterally in the [1120] direction.

The side surface of the dielectric multilayer film 41 is perpendicular or substantially perpendicular to the substrate 11. The opening 41H provided between the adjacent dielectric multilayer films 41 does not necessarily have a uniform width between all the adjacent dielectric multilayer films 41, but in the present embodiment, at least the first The width of the groove-shaped opening 41H between the 1DBR layer 41A and the dielectric multilayer film 41 adjacent to the first DBR layer 41A is provided to satisfy the following range. FIG. 2 is a diagram for explaining the main part of this embodiment (the positional relationship between the first DBR layer 41A, the opening 41H, and the current injection region R). In the first DBR layer 41A, the opening 41H, and the current injection region R, the distance (width of the opening 41H) between the first DBR layer 41A and the dielectric multilayer film 41 adjacent to the first DBR layer 41A is W, and the first DBR. When the thickness of the layer 41A in the normal direction with respect to the substrate 11 is H, the first DBR layer 41A, the opening 41H, and the current injection region R include the edge of the upper surface of the first DBR layer 41A and the edge of the current injection region R. Is formed such that an angle θ between a line segment LN connecting the two and the upper surface of the first DBR layer 41A is not less than arctan (H / W) and not more than 90 °. In Figure 2, the edge of the upper surface of the 1DBR layer 41A, and the point where the line segment LN contact with each other is represented by X _1, and the edge of the current injection region R, the point where the line segment LN contact with each other It is represented by X _2. Accordingly, the current injection region R can be confirmed from the opening 41H without being blocked by the first DBR layer 41A from the back surface (surface S2) side of the substrate 11. As a specific example of each value satisfying this condition, for example, arctan (H / W) when the width W of the opening 41H is 4.5 μm and the thickness H of the first DBR layer 41A is 2.5 μm is about 29. °. Therefore, the angle θ formed by the line segment LN and the upper surface of the first DBR layer 41A may be in the range of 29 ° ≦ θ ≦ 90 °, for example, 45 °.

The thickness of each dielectric film can be adjusted as appropriate depending on the material used, and is determined by the light emission wavelength λ0 and the refractive index n of the material used at the light emission wavelength λ0. Specifically, an odd multiple of λ0 / (4n) is preferable. For example, in a light emitting device having an emission wavelength λ0 of 410 nm, when the dielectric multilayer film 41 is made of SiO _x / NbO _y , the thickness of each dielectric film is preferably about 40 nm to 70 nm. The number of stacked layers is preferably 5 or more, and more preferably 15 or more. The total thickness of the dielectric multilayer film 41 is preferably, for example, 0.6 μm to 3.0 μm.

As shown in FIG. 3, the planar shape of the dielectric multilayer film 41 is, for example, a lattice (rectangular) shape (A), a polygonal shape including a regular hexagon (B), a circular shape including an ellipse (C), a stripe shape ( D) or an island shape. The cross-sectional shape of the dielectric multilayer film 41 may be rectangular as shown in FIG. 3, or may be formed in a trapezoidal shape.

The second DBR layer 42 is provided at a position facing the first DBR layer 41 </ b> A with the semiconductor layer 20 in between, specifically, provided on the transparent electrode 32. Similar to the dielectric multilayer film 41, the second DBR layer 42 is made of an oxide or nitride such as Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Ti (for example, SiN _x , AlN _x , AlGaN, GaN _x , BN _x, etc.) or fluoride. As with the 2DBR layer 42 a dielectric multilayer film 41, a high refractive index material such as SiN _x or TaO _x, it is preferable to alternately laminating a low refractive index material such as SiO _x, thereby, high light Reflectance can be obtained. In order to obtain a desired light reflectance, in addition to the material constituting each dielectric film, the film thickness, the number of stacked layers, and the like may be appropriately selected. The thickness of each dielectric film can be adjusted as appropriate depending on the material used, and is determined by the light emission wavelength λ0 and the refractive index n of the material used at the light emission wavelength λ0. Specifically, an odd multiple of λ0 / (4n) is preferable. For example, in a light emitting device having an emission wavelength λ0 of 410 nm, when the dielectric multilayer film 41 is made of SiO _x / NbO _y , the thickness of each dielectric film is preferably about 40 nm to 70 nm. The number of stacked layers is 2 or more, preferably 2 to 15. The total thickness of the dielectric multilayer film 41 is preferably, for example, 0.6 μm to 1.7 μm.

(1-2. Manufacturing method)
The semiconductor laser 1 of the present embodiment can be manufactured as follows, for example.

4A to 4C show a method of manufacturing the semiconductor laser 1 in the order of steps. First, as shown in FIG. 4A, a plurality of dielectric multilayer films 41 are formed on the substrate 11. Specifically, for example, after forming a multilayer film in which, for example, five layers of SiO _x films and SiN _x films are alternately stacked using any film formation method such as sputtering, CVD, and vapor deposition, By selectively etching, a plurality of dielectric multilayer films 41 whose side surfaces are surrounded by groove-shaped openings 41H are formed. For the etching step, wet etching using hydrofluoric acid or the like, dry etching using an RIE apparatus, or the like can be used. Thereby, a plurality of dielectric multilayer films 41 are formed in the surface of the substrate 11.

Next, as shown in FIG. 4B, the semiconductor layer 20 covering the dielectric multilayer film 41 and the insulating film 24 having the openings 24A are formed. Specifically, the dielectric multilayer film 41 is used as a selective growth mask, and the substrate 11 is placed in a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus and heated to a desired temperature. For example, the semiconductor layer 20 including the first semiconductor layer 21 made of n-type GaN and the active layer (light emitting layer) 22, for example, the second semiconductor layer 23 made of p-type GaN, is grown. For growth, trimethylgallium (TMGa) as a Ga source, trimethylaluminum (TMAl) as an Al source, trimethylindium (TMIn) as an In source, silane (SiH ₄ ) as an n-type impurity Si source, and p-type impurity Mg Cyclopentadienylmagnesium (Cp ₂ Mg) is used as a raw material for the above, and ammonia gas (NH ₃ ) is used as the N raw material. Here, for example, the first semiconductor layer 21 is grown to 5 μm, the active layer 22 is grown to 80 nm, and the second semiconductor layer 23 is grown to 100 nm. Subsequently, an insulating film 24 for forming a current confinement structure is formed. For example, the SiO ₂ film is formed to have a thickness of, for example, 200 nm by using any film formation method such as sputtering, CVD, and vapor deposition. An insulating film 24 having an opening 24A from which 23 is exposed is formed. For the etching step, wet etching using hydrofluoric acid or the like, dry etching using an RIE apparatus, or the like can be used. As a result, the semiconductor layer 20 covering the dielectric multilayer film 41 and the insulating film 24 having the opening 24A having a current confinement structure are formed. Here, the area of the current injection region R is preferably less than or equal to half of the area of the dielectric multilayer film 41 (first DBR layer 41A) facing the current injection region R. The area of the current injection region R is, for example, about 25πμm ² . In this case, the current injection region R can be formed while avoiding a defect region (singular point) of the semiconductor layer 20.

Subsequently, as shown in FIG. 4C, the transparent electrode 32, the second electrode 33, and the second DBR layer 42 are formed. Specifically, for example, an ITO film is formed to a thickness of 50 nm by using any film formation method such as sputtering, CVD, and vapor deposition, and then selectively etched, thereby transparent electrode 32 having a desired shape. Form. For the etching process, wet etching using hydrochloric acid or the like, dry etching using a reactive ion etching apparatus, or the like can be used. Next, for example, Au, Pt, and Ti are formed in this order by using any film forming method such as sputtering, CVD, and vapor deposition, and then selectively etched to form Ti / Pt only at a desired portion. The second electrode 33 is formed leaving the / Au film. For the etching process, wet etching using acid or the like, dry etching using a reactive ion etching apparatus or the like, lift-off using the PR method, or the like can be used. Subsequently, for example, after forming a dielectric multilayer film in which, for example, five layers of SiO _x films and SiN _x films are alternately formed by using any film forming method such as sputtering, CVD, and vapor deposition, for example, selective The second DBR layer 42 having a desired shape is formed by etching. For the etching step, wet etching using hydrofluoric acid or the like, dry etching using an RIE apparatus, or the like can be used.

Next, after the substrate 11 is ground and polished from the back side, the first electrode 31 is formed. Finally, the element is cut out from the substrate 11 by cleavage or the like. Thus, the semiconductor laser 1 shown in FIG. 1 is completed.

As described above, the semiconductor laser 1 includes the plurality of dielectric multilayer films 41, the first semiconductor layer 21, the active layer 22, the second semiconductor layer 23, the transparent electrode 32, and the second DBR layer 42 on the surface S1 of the substrate 11. The first electrode 31 is formed on the other surface S2 stacked in this order and facing the surface S1 of the substrate 11. In either one of the first DBR layer 41A and the second DBR layer 42 (here, on the second DBR layer 42 side), a current that narrows the current injection region in order to increase the current injection efficiency into the active layer 22 and reduce the threshold ground current. A constriction structure (opening 24A of insulating film 24) is provided. In the semiconductor laser 1, the current injected from the first electrode 31 and the transparent electrode 32 is narrowed by the current confinement structure and then injected into the active layer 22. Thereby, light emission by recombination of electrons and holes occurs. This light is reflected by the first DBR layer 41A and the second DBR layer 42, causes laser oscillation at a predetermined wavelength, and is emitted to the outside through the first DBR layer 41A or the second DBR layer 42.

(1-3. Action and effect)
As described above, in a surface emitting laser having a DBR layer above and below a semiconductor layer including an active layer, in order to cause light to resonate between the DBR layers to generate laser oscillation, control of the resonator length and the DBR layer The surface needs to be smooth on the order of sub-nanometers. For this reason, a surface emitting laser in which a semiconductor layer is grown using the DBR layer as a selective growth mask and this DBR layer is embedded in the semiconductor layer has been developed. However, when a light extraction diagram is formed on the DBR layer. The DBR layer was designed to be larger than the light extraction portion in consideration of the alignment variation.

However, when a large-diameter dielectric multilayer film is embedded, it becomes difficult to inspect device characteristics and repair defects in the electrode. In the device characteristic inspection, for example, excitation light is irradiated from the back surface side of the substrate to the active layer serving as the light emitting layer. At this time, it is desirable to directly excite the active layer while avoiding the light absorption of GaN constituting the semiconductor layer 20 and the stop band of the dielectric multilayer film, but when a large-diameter dielectric multilayer film is formed, It was difficult to irradiate the excitation light avoiding the multilayer film. In addition, a transparent electrode material such as ITO is used for an electrode used in a general nitride surface emitting laser, but ITO is likely to include defects. Defects in this ITO film can be repaired by irradiating laser light, but in order to irradiate the defective part with laser light for repair from the back side of the substrate, a large-diameter dielectric layer is obstructed. It was easy to be. For this reason, it is difficult to improve the reliability, and the manufacturing yield is reduced.

On the other hand, in the present embodiment, the angle formed by the line segment LN connecting the edge of the upper surface of the first DBR layer 41A and the edge of the current injection region R with the shortest distance and the upper surface of the first DBR layer 41A. θ is not less than arctan (H / W) and not more than 90 °.

FIG. 5 schematically shows a method for inspecting the device characteristics of the semiconductor laser 1. FIG. 6 schematically shows a method for repairing a defect in the transparent electrode 32 provided in the semiconductor laser 1. As described above, the inspection of device characteristics and the repair of defects in the electrode (transparent electrode 32) are performed by using excitation light L1 or laser light L2 from the back surface (surface S2) side of the substrate 11 and the active layer 22 or transparent electrode 32, respectively. It is done by irradiating. In the present embodiment, as described above, since the angle θ is not less than arctan (H / W) and not more than 90 °, the laser beam L2 is supplied from the substrate 11 side without being blocked by the first DBR layer 41A. The injection region R can be selectively irradiated with the excitation light L1 on the active layer 22 below the current injection region R. Therefore, device characteristics inspection (photoexcitation inspection) and defect repair of the transparent electrode 32 can be performed regardless of external factors. As a result, the reliability and manufacturing yield of the semiconductor laser 1 are improved.

Hereinafter, a second embodiment of the present technology will be described. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

<2. Second Embodiment>
FIG. 7 illustrates an example of a cross-sectional configuration of a nitride surface emitting laser (semiconductor laser 2) according to the second embodiment of the present technology. The semiconductor laser 2 is different from the first embodiment in that the semiconductor laser 1 includes a dielectric multilayer film 51 instead of the dielectric multilayer film 41 in the semiconductor laser 1 of the first embodiment. The dielectric multilayer film 51 has a laminated structure similar to that of the dielectric multilayer film 41, and the cross-sectional configuration of the dielectric multilayer film 41 is that the side surface of the dielectric multilayer film 51 is inclined in a forward tapered shape. It is different. When the dielectric multilayer film 51 facing the second DBR layer 42 among the plurality of dielectric multilayer films 51 is the first DBR layer 51A, the pair of first DBR layer 51A and second DBR layer 42 function as a resonator. The semiconductor layer 20 has a configuration in which a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 are stacked in this order from the substrate 11 side. Each dielectric multilayer film 51 is embedded with the first semiconductor layer 21, and a groove-shaped opening 51H is formed between the first DBR layer 51A and the dielectric multilayer film 51 adjacent to the first DBR layer 51A. Is formed. An angle between a line segment connecting the edge of the upper surface of the first DBR layer 51A and the edge of the current injection region R with the shortest distance and the upper surface of the first DBR layer 51A is within a predetermined range. The semiconductor laser 2 has a first electrode 31 in contact with the surface S2 of the substrate 11 (the surface facing the surface S1). Note that the semiconductor laser 1 in FIG. 7 is schematically shown and is different from actual dimensions.

(2-1. Main part configuration)
A plurality of dielectric multilayer films 51 are provided in the plane of the substrate 11 and are embedded with the first semiconductor layer 21. A groove-shaped opening 51H is provided between adjacent dielectric multilayer films 51, and the first semiconductor layer 21 is embedded in the opening 51H. The dielectric multilayer film 51 includes, for example, Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Ti, and other oxides and nitrides (for example, SiN _x , AlN _x , AlGaN, GaN _x , BN _x, etc.) or fluoride. _{_{Specifically, SiO x, TiO x, NbO}} x, ZrO x, TaO x, ZnO x, AlO x, HfO x, SiN x, AlN x , and the like. The first DBR layer 51A includes two or more kinds of dielectric films made of dielectric materials having different refractive indexes among the dielectric materials (for example, TaO _x having a high refractive index and SiO _x having a low refractive index). It is preferable that the layers are alternately stacked. Thereby, the light reflection effect is obtained. The combination of two dielectric films, for example, in addition to _{_{_{SiO x / TaO x, SiO x}}} / SiN x, SiO x / NbO x, SiO x / ZrO x, SiO x / AlN x , and the like. In order to obtain a desired light reflectance, the material, the film thickness, the number of stacked layers, and the like constituting each dielectric film may be appropriately selected. For example, the dielectric multilayer film 51 is preferably arranged or arranged so as to grow laterally in the [1120] direction.

The opening 51H provided between the adjacent dielectric multilayer films 51 does not necessarily have a uniform width between all the adjacent dielectric multilayer films 51, but in the present embodiment, the first DBR is used. The width of the groove-shaped opening 51H between the layer 51A and the dielectric multilayer film 51 adjacent to the first DBR layer 51A is provided so as to satisfy the following range.

FIG. 8 is for explaining the main part of this embodiment (the positional relationship between the first DBR layer 51A, the opening 51H and the current injection region R). In the first DBR layer 51A, the opening 51H, and the current injection region R, the distance (width of the opening 51H) between the first DBR layer 51A and the dielectric multilayer film 51 adjacent to the first DBR layer 51A is W, and the first DBR. When the distance from the intersection of the perpendicular drawn from the outer edge of the upper surface of the layer 51A and the bottom of the first DBR layer 51A to the opening 51H is W ′, and the thickness of the first DBR layer 51A in the normal direction to the substrate 11 is H, The first DBR layer 51A, the opening 51H, and the current injection region R include a line segment LN connecting the edge of the upper surface of the first DBR layer 51A and the edge of the current injection region R at the shortest distance, and the upper surface of the first DBR layer 51A. Is formed so as to be not less than arctan (H / (W + W ′)) and not more than 90 °. 8, the edge of the upper surface of the 1DBR layer 51A, and the point where the line segment LN contact with each other is represented by X _1, and the edge of the current injection region R, the point where the line segment LN contact with each other It is represented by X _2. Thus, the current injection region R can be confirmed from the opening 51H without being blocked by the first DBR layer 51A from the back surface (surface S2) side of the substrate 11. Specific numerical values of the values satisfying this condition are, for example, an opening width W of 4.5 μm, a distance W ′ from the intersection of the perpendicular drawn from the upper outer peripheral portion X1 and the bottom side of the first DBR layer 51A to the opening 51H. And arctan (H / (W + W ′)) is about 21 ° when the thickness H of the first DBR layer 41A is 2.5 μm. Therefore, the angle θ formed by the line segment LN and the upper surface of the first DBR layer 51A may be in a range of 21 ° ≦ θ ≦ 90 °, and is about 30 °, for example.

In addition to the forward tapered shape, the cross-sectional shape of the dielectric multilayer film 51 is a part of the upper corner of the dielectric multilayer film 51 (for example, the dielectric multilayer film 51, for example, as shown in FIG. 9A). It is good also as a shape where a part of side surfaces S1 and S2) was shaved from the upper surface. Further, the cross-sectional shape of the dielectric multilayer film 51 does not necessarily have to be symmetric, and even if the upper corner of only one side surface (here, the side surface S1) is cut as shown in FIG. 9B. Good. Furthermore, it is not necessary that all of the plurality of dielectric multilayer films 51 provided on the substrate 11 have the same shape, and only the dielectric multilayer film 51 that becomes the first DBR layer 51A is processed into the above shape. Good.

Other configurations are the same as those in the first embodiment.

(2-2. Action and effect)
In the present embodiment, an angle θ formed by a line segment LN connecting the edge of the upper surface of the first DBR layer 51A and the edge of the current injection region R with the shortest distance and the upper surface of the first DBR layer 51A is arctan ( H / (W + W ′)) to 90 °.

FIG. 10 schematically shows a method for inspecting the device characteristics of the semiconductor laser 2. FIG. 11 schematically shows a method for repairing a defect in the transparent electrode 32 provided in the semiconductor laser 2. As described above, the inspection of device characteristics and the repair of defects in the electrode (transparent electrode 32) are performed by using excitation light L1 or laser light L2 from the back surface (surface S2) side of the substrate 11 and the active layer 22 or transparent electrode 32, respectively. It is done by irradiating. The laser beam L2 can be selectively irradiated to the current injection region R and the excitation light L1 can be selectively irradiated to the active layer 22 below the current injection region R without being blocked by the first DBR layer 51A from the substrate 11. Therefore, device characteristics inspection (photoexcitation inspection) and defect repair of the transparent electrode 32 can be performed regardless of external factors. As a result, the reliability and manufacturing yield of the semiconductor laser 2 are improved.

Although the present technology has been described with reference to the first embodiment and the second embodiment, the present technology is not limited to the above-described embodiments and the like, and various modifications can be made.

It should be noted that the effects described in the present specification are merely examples and are not limited to these, and other effects may be obtained.

In addition, this technique can also take the following structures.
(1)
A first dielectric multilayer film and a second dielectric multilayer film provided on the substrate and adjacent to each other;
A current injection region provided at a position facing the first dielectric multilayer film;
An opening provided between the first dielectric multilayer film and the second dielectric multilayer film;
When the distance between the first dielectric multilayer film and the second dielectric multilayer film is W, and the thickness of the first dielectric multilayer film in the normal direction to the substrate is H,
The first dielectric multilayer film, the opening, and the current injection region include a line segment that connects an edge of the upper surface of the first dielectric multilayer film and an edge of the current injection region with the shortest distance; A nitride surface emitting laser formed such that an angle θ formed with the upper surface of the first dielectric multilayer film is not less than arctan (H / W) and not more than 90 °.
(2)
The nitride surface emitting laser according to (1), wherein a side surface of the first dielectric multilayer film is perpendicular to the substrate.
(3)
The nitride surface emitting laser according to (1) or (2), wherein an area of the current injection region is not more than half of an area of the first dielectric multilayer film.
(4)
A first semiconductor layer;
An active layer provided on the first semiconductor layer;
A second semiconductor layer provided on the active layer and having an emission window for emitting light emitted from the active layer;
A third dielectric provided at a position facing one of the first dielectric multilayer films embedded in the first semiconductor layer with the first semiconductor layer, the active layer, and the second semiconductor layer in between. The nitride surface emitting laser according to any one of (1) to (3), further including a body multilayer film.
(5)
The nitride surface emitting laser according to (4), wherein the first semiconductor layer, the active layer, and the second semiconductor layer are formed of a GaN-based compound semiconductor.
(6)
A first dielectric multilayer film and a second dielectric multilayer film provided on the substrate and adjacent to each other;
A current injection region provided at a position facing the first dielectric multilayer film;
An opening provided between the first dielectric multilayer film and the second dielectric multilayer film;
The distance between the first dielectric multilayer film and the second dielectric multilayer film is W, the perpendicular drawn from the outer edge of the upper surface of the first dielectric multilayer film, and the bottom of the first dielectric multilayer film When the distance from the intersection to the opening is W ′, and the thickness of the first dielectric multilayer film in the normal direction to the substrate is H,
The first dielectric multilayer film, the opening, and the current injection region include a line segment that connects the edge of the upper surface of the first dielectric multilayer film and the edge of the current injection region with the shortest distance; 1. A nitride surface emitting laser formed so that an angle θ formed with an upper surface of a dielectric multilayer film is not less than arctan (H / (W + W ′)) and not more than 90 °.
(7)
The nitride surface emitting laser according to (6), wherein at least a part of the side surface of the first dielectric multilayer film has a forward tapered shape.
(8)
The nitride surface emitting laser according to (6) or (7), wherein an area of the current injection region is not more than half of an area of the first dielectric multilayer film.
(9)
A first semiconductor layer;
An active layer provided on the first semiconductor layer;
A second semiconductor layer provided on the active layer and having an emission window for emitting light emitted from the active layer;
A third dielectric provided at a position facing one of the first dielectric multilayer films embedded in the first semiconductor layer with the first semiconductor layer, the active layer, and the second semiconductor layer in between. Body multilayer film,
The nitride surface emitting laser according to any one of (6) to (8), wherein the first dielectric multilayer film is a first light reflecting layer.
(10)
The nitride surface emitting laser according to (9), wherein the first semiconductor layer, the active layer, and the second semiconductor layer are formed of a GaN-based compound semiconductor.

This application claims priority based on Japanese Patent Application No. 2015-172748 filed on September 2, 2015 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims

A first dielectric multilayer film and a second dielectric multilayer film provided on the substrate and adjacent to each other;
A current injection region provided at a position facing the first dielectric multilayer film;
An opening provided between the first dielectric multilayer film and the second dielectric multilayer film;
When the distance between the first dielectric multilayer film and the second dielectric multilayer film is W, and the thickness of the first dielectric multilayer film in the normal direction to the substrate is H,
The first dielectric multilayer film, the opening, and the current injection region include a line segment that connects an edge of the upper surface of the first dielectric multilayer film and an edge of the current injection region with the shortest distance; A nitride surface emitting laser formed such that an angle θ formed with the upper surface of the first dielectric multilayer film is not less than arctan (H / W) and not more than 90 °.
The nitride surface-emitting laser according to claim 1, wherein a side surface of the first dielectric multilayer film is perpendicular to the substrate.
2. The nitride surface emitting laser according to claim 1, wherein an area of the current injection region is not more than half of an area of the first dielectric multilayer film.
A first semiconductor layer;
An active layer provided on the first semiconductor layer;
A second semiconductor layer provided on the active layer and having an emission window for emitting light emitted from the active layer;
A third dielectric provided at a position facing one of the first dielectric multilayer films embedded in the first semiconductor layer with the first semiconductor layer, the active layer, and the second semiconductor layer in between. The nitride surface emitting laser according to claim 1, further comprising a multilayered body film.
The nitride surface-emitting laser according to claim 4, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are made of a GaN-based compound semiconductor.
A first dielectric multilayer film and a second dielectric multilayer film provided on the substrate and adjacent to each other;
A current injection region provided at a position facing the first dielectric multilayer film;
An opening provided between the first dielectric multilayer film and the second dielectric multilayer film;
The distance between the first dielectric multilayer film and the second dielectric multilayer film is W, the perpendicular drawn from the outer edge of the upper surface of the first dielectric multilayer film, and the bottom of the first dielectric multilayer film When the distance from the intersection to the opening is W ′, and the thickness of the first dielectric multilayer film in the normal direction to the substrate is H,
The first dielectric multilayer film, the opening, and the current injection region include a line segment that connects the edge of the upper surface of the first dielectric multilayer film and the edge of the current injection region with the shortest distance; 1. A nitride surface emitting laser formed so that an angle θ formed with an upper surface of a dielectric multilayer film is not less than arctan (H / (W + W ′)) and not more than 90 °.
The nitride surface emitting laser according to claim 6, wherein at least a part of a side surface of the first dielectric multilayer film has a forward tapered shape.
The nitride surface emitting laser according to claim 6, wherein an area of the current injection region is not more than half of an area of the first dielectric multilayer film.
A first semiconductor layer;
An active layer provided on the first semiconductor layer;
A second semiconductor layer provided on the active layer and having an emission window for emitting light emitted from the active layer;
A third dielectric provided at a position facing one of the first dielectric multilayer films embedded in the first semiconductor layer with the first semiconductor layer, the active layer, and the second semiconductor layer in between. Body multilayer film,
The nitride surface emitting laser according to claim 6, wherein the first dielectric multilayer film is a first light reflecting layer.
The nitride surface-emitting laser according to claim 9, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are made of a GaN-based compound semiconductor.