JP2004048079A - Semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser employing a nitride based III-V compound semiconductor in which a high output can be ensured easily. <P>SOLUTION: Between a p-side contact layer 43 and a p-side electrode 52, a high-resistance layer 64 is provided in correspondence with the region of an active layer 30 except for the opposite ends thereof in the direction A of a resonator. The opposite ends of the active layer 30 in the direction A of the resonator are current non-injection regions and the part of the active layer 30 corresponding to the p-side contact layer 43 in the region except for the opposite ends in the direction A of the resonator is the current injection region. Consequently, non-emission recombination is prevented effectively on the end faces 1a and 1b of the resonator and in the vicinity thereof, a temperature rise is suppressed on the end faces 1a and 1b of the resonator and in the vicinity thereof, and COD is prevented. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a semiconductor laser using a nitride III-V compound semiconductor containing at least one of the group 3B elements and at least nitrogen (N) of the group 5B element.

In recent years, in optical disk devices and magneto-optical disk devices, there has been an increasing demand for higher recording / reproducing densities or higher resolutions. To achieve this, light emission in a blue wavelength band or a short wavelength region in the ultraviolet region is required. Research and development of possible semiconductor lasers (laser diodes; LDs) are being actively conducted. As a material suitable for forming a semiconductor laser capable of emitting light in such a short wavelength region, a nitride III-V compound semiconductor represented by GaN, AlGaN mixed crystal or GaInN mixed crystal is known. . In order to realize recording / reproducing of a rewritable disk by a semiconductor laser using a nitride III-V compound semiconductor, a large optical output of at least about 30 mW is required.

However, this type of semiconductor laser has a problem in that optical damage (Catastrophic Optical Damage; COD) occurs near the pair of end faces facing each other in the cavity direction, and it is difficult to increase the output. In the COD, non-radiative recombination of electrons and holes occurs more in the vicinity of the end face where a high-density interface state exists than in the inside, and the carrier density decreases. It is known that this is caused by a series of phenomena such as a rise in temperature, a decrease in band gap, light absorption, and a further rise in temperature.

As one of means for solving the above problem, a gallium nitride based semiconductor laser device has been proposed in which the length of the ohmic electrode for supplying current to the active layer in the resonator direction is shorter than the length of the resonator. (See Patent Document 1). However, this semiconductor laser device has a problem that the manufacturing process is complicated.
JP-A-11-340573

The present invention has been made in view of such a problem, and an object of the present invention is to provide a semiconductor laser using a nitride-based III-V compound semiconductor that can easily achieve high output.

A semiconductor laser according to the present invention includes an n-type semiconductor layer and an active layer each composed of a nitride III-V compound semiconductor containing at least one of the group 3B elements and at least nitrogen (N) of the group 5B element. And the p-type semiconductor layer is sequentially laminated, the n-side electrode is in ohmic contact with the n-type semiconductor layer, and the p-side electrode is in ohmic contact with the p-type semiconductor layer, The p-type semiconductor layer is provided corresponding to a region excluding at least one end of the active layer in the resonator direction, and has a p-side contact layer in ohmic contact with the p-side electrode; an underlayer provided between the p-side electrode and the p-side contact layer so as to correspond to the entire region of the active layer; One end portion is a current non-injection region due to an insulating layer or a high-resistance layer interposed between the p-side electrode and the base layer. The thickness in the stacking direction is smaller than the p-side contact layer, and the surface of the p-side electrode is configured such that the vicinity of the end has a lower step than the region corresponding to the p-side contact layer. .

In the semiconductor laser according to the present invention, as a current non-injection region, at least one end in the resonator direction between the p-side electrode and the base layer (p-side cladding layer) is formed of an insulating layer or a high-resistance layer. The presence of the region suppresses a temperature rise near the end during operation. Further, the thickness of the insulating layer or the high resistance layer in the laminating direction is smaller than that of the p-side contact layer, and a step is formed on the surface of the p-side electrode. That is, the vicinity of the end of the p-side electrode is lower than the region corresponding to the p-side contact layer. Therefore, when mounting is reversed, when soldering to the submount, excess solder protrudes to the end face, There is no danger of reaching the active layer.

According to the semiconductor laser of the present invention, a current non-injection region made of an insulating layer or a high-resistance layer is provided at at least one end in the resonator direction between the p-side electrode and the underlying layer (p-side cladding layer). Since the thickness of the insulating layer or the high-resistance layer in the stacking direction is made thinner than the p-side contact layer so as to provide a step on the surface of the p-side electrode, a temperature rise near the end portion during operation is suppressed, It is possible to prevent the occurrence of COD at the end portion, and to easily increase the output. In addition, at the time of mounting on the submount, there is no possibility that the surplus solder protrudes to the end face and reaches the active layer, so that the mounting operation can be performed smoothly.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a configuration of a semiconductor laser 1 according to a first embodiment of the present invention. The semiconductor laser 1 has an n-type semiconductor layer 20, an active layer 30, and a p-type semiconductor layer 40 laminated on one surface of a substrate 11 in this order from the substrate 11 side. The substrate 11 is made of, for example, sapphire (α-Al ₂ O ₃ ) having a thickness in the stacking direction (hereinafter, simply referred to as a thickness) of about 80 μm, and includes an n-type semiconductor layer 20, an active layer 30, and a p-type semiconductor layer. The type semiconductor layer 40 and the like are formed on the c-plane of the substrate 11. The n-type semiconductor layer 20, the active layer 30, and the p-type semiconductor layer 40 are at least one of Group 3B elements in the short-periodic table and at least nitrogen of the Group 5B elements in the short-periodic table. , Respectively.

The n-type semiconductor layer 20 has, for example, an n-side contact layer 21, an n-type cladding layer 22, and an n-type guide layer 23 that are sequentially stacked from the substrate 11 side. The n-side contact layer 21 has a thickness of, for example, 3 μm, and is made of n-type GaN to which silicon (Si) is added as an n-type impurity. The n-type cladding layer 22 has a thickness of, for example, 1 μm, and is made of an n-type AlGaN mixed crystal to which silicon is added as an n-type impurity. The n-type guide layer 23 has a thickness of, for example, 0.1 μm, and is made of n-type GaN to which silicon is added as an n-type impurity.

The active layer 30 has, for example, a thickness of 30 nm and has a multiple quantum well structure in which Ga _x In ₁ -xN (where x ≧ 0) mixed crystal layers having different compositions are stacked.

The p-type semiconductor layer 40 includes, for example, a p-type guide layer 41, a p-type cladding layer 42, and a p-side contact layer 43 that are sequentially stacked from the active layer 30 side. The p-type guide layer 41 has a thickness of, for example, 0.1 μm, and is made of p-type GaN to which magnesium (Mg) is added as a p-type impurity. The p-type cladding layer 42 has a thickness of, for example, 0.8 μm, and is made of a p-type AlGaN mixed crystal to which magnesium is added as a p-type impurity. The p-side contact layer 43 has, for example, a thickness of 0.5 μm and is made of p-type GaN to which magnesium is added as a p-type impurity. Note that a part of the p-type cladding layer 42 and the p-side contact layer 43 are formed in a narrow band shape extending in the resonator direction A, and perform current confinement.

The p-side contact layer 43 is provided corresponding to at least one end of the active layer 30 in the resonator direction A, for example, a region other than both ends. As a result, at least one end in the resonator direction A of the active layer 30 is a current non-injection region, and the current injection region functioning as a light emitting unit is other than at least one end in the resonator direction A. The region corresponds to the p-side contact layer 43. Here, the current non-injection region does not mean a region in which no current flows, but a region in which no current is actively injected. It is preferable that the width of the current non-injection region in the resonator direction A be within 100 μm. If it is larger than that, the contact portion between the p-side contact layer 43 and a p-side electrode 52 described later decreases, so that the drive voltage increases and a current is uniformly supplied from the p-side electrode 52 to the p-side contact layer 43. This is because the threshold current increases without being injected. More preferably, the width of the current non-injection region in the resonator direction A is in the range of 10 μm to 50 μm. This is because the operating characteristics of the semiconductor laser 1 are more stable within this range.

In the semiconductor laser 1, the width of the n-side contact layer 21 in the direction perpendicular to the cavity direction A is different from that of the other n-type cladding layer 22, n-type guide layer 23, active layer 30, and p-type semiconductor layer. The n-type cladding layer 22, the n-type guide layer 23, the active layer 30, and the p-type semiconductor layer 40 are laminated on a part of the n-side contact layer 21.

An insulating film 12 made of, for example, silicon dioxide (SiO ₂ ) is formed on the surface of the n-side contact layer 21 and the surface of the p-type semiconductor layer 40. The insulating film 12 is provided with openings corresponding to the n-side contact layer 21 and the p-side contact layer 43, respectively. The openings corresponding to these openings are provided on the n-side contact layer 21 and the p-side contact layer 43. Thus, an n-side electrode 51 and a p-side electrode 52 are respectively formed. The n-side electrode 51 has a structure in which, for example, titanium (Ti) and aluminum (Al) are sequentially laminated and alloyed by heat treatment, and is in ohmic contact with the n-side contact layer 21. The p-side electrode 52 has a structure in which, for example, palladium (Pd), platinum (Pt), and gold (Au) are sequentially stacked, and is in ohmic contact with the p-side contact layer 43. Note that the entire surface of the p-side contact layer 43 is exposed via the opening of the insulating film 12 and is in ohmic contact with the entire surface of the p-side electrode 52.

In the semiconductor laser 1, a pair of side faces facing the active layer 30 in the resonator direction A are resonator end faces 1a and 1b, and a pair of not shown paired resonator end faces 1a and 1b are provided. Are formed respectively. The reflectance is adjusted so that one of the pair of reflecting mirror films has a low reflectance and the other has a high reflectance. Thus, the light generated in the active layer 30 reciprocates between the pair of reflecting mirror films and is amplified, and is emitted as a laser beam from the reflecting mirror film having a low reflectance. Note that the p-side contact layer 43 is provided corresponding to the other region except one end of the active layer 30 in the resonator direction A, and only one end is used as a current non-injection region. It is preferable that the end portion side of the current non-injection region be a reflecting mirror film having a low reflectance.

半導体 The semiconductor laser 1 having such a configuration can be manufactured as follows. Here, a case where a plurality of semiconductor lasers 1 are manufactured will be described as an example.

FIGS. 2 and 3 show the manufacturing process for one semiconductor laser formation region. 2 (A), 2 (B) and 3 (A) show a cross-sectional structure in a direction perpendicular to the resonator direction A. FIG. 3 (B) shows a p-side contact layer along the resonator direction A. 43 shows a cross-sectional structure cut to include 43. First, for example, a substrate 11 having a plurality of semiconductor laser forming regions and made of sapphire having a thickness of about 400 μm is prepared. Next, as shown in FIG. 2A, an n-side contact layer 21 of n-type GaN and an n-type cladding layer 22 of n-type AlGaN mixed crystal are formed on the c-plane of the substrate 11 by, for example, MOCVD. , An n-type guide layer 23 of n-type GaN, an active layer 30 of GaInN mixed crystal, a p-type guide layer 41 of p-type GaN, a p-type cladding layer 42 of p-type AlGaN mixed crystal, and a p-type GaN The p-side contact layer 43 is sequentially grown.

When MOCVD is performed, for example, a source gas of gallium is trimethylgallium ((CH ₃ ) ₃ Ga), a source gas of aluminum is, for example, trimethyl aluminum ((CH ₃ ) ₃ Al), and a source gas of indium is, for example. For example, ammonia (NH ₃ ) is used as a source gas for trimethylindium ((CH ₃ ) ₃ In) and nitrogen, respectively. For example, monosilane (SiH ₄ ) is used as a silicon source gas, and bis = cyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg) is used as a magnesium source gas.

After growing the p-side contact layer 43, a not-shown striped mask made of silicon dioxide is formed on the p-side contact layer 43 by using, for example, an evaporation method. Subsequently, as shown in FIG. 2B, a part of the p-side contact layer 43 and a part of the p-type cladding layer 42 are selectively etched by RIE (Reactive Ion Etching) or the like using this mask, and The upper part of the mold cladding layer 42 and the p-side contact layer 43 are formed in a narrow band shape. After that, the mask is removed.

Next, a mask (not shown) made of silicon dioxide is selectively formed on the p-side contact layer 43 and the p-type cladding layer 42 by using, for example, an evaporation method. Subsequently, as shown in FIG. 3A, the p-type cladding layer 42, the p-type guide layer 41, the active layer 30, the n-type guide layer 23, the n-type clad layer 22, and the n-side A part of the contact layer 21 is sequentially etched by RIE or the like to expose the n-side contact layer 21 on the surface. After that, the mask is removed.

After removing the mask, a mask (not shown) made of silicon dioxide is formed on the entire surface by, for example, a vapor deposition method. Subsequently, using a photolithography technique, openings are formed in a mask (not shown) corresponding to the division surface of the semiconductor laser formation region in the direction perpendicular to the cavity direction A. Next, as shown in FIG. 3B, for example, RIE is performed using the mask in which the opening is formed, and the p-side contact layer 43 is formed in at least one of the semiconductor laser formation regions in the direction perpendicular to the cavity direction A. , For example, both ends are removed. After that, the mask is removed.

After removing the mask, an insulating film 12 made of silicon dioxide is formed on the entire surface by, for example, an evaporation method. Subsequently, a not-shown resist film is formed on the entire surface, and a not-shown resist pattern having an opening corresponding to the formation position of the n-side electrode 51 is formed. Thereafter, etching is performed using this resist pattern as a mask, and the insulating film 12 is selectively removed to form an opening in the insulating film 12. Next, for example, titanium and aluminum were sequentially deposited on the entire surface (that is, on the n-side contact layer 21 from which the insulating film 12 was selectively removed and the resist film not shown), and a resist film (not shown) was deposited thereon. By removing (lifting off) together with each metal, an n-side electrode 51 is formed. Subsequently, a heat treatment is performed to alloy the n-side electrode 51.

After performing the heat treatment, a resist film (not shown) is formed on the entire surface, and a resist pattern (not shown) having an opening corresponding to the p-side contact layer 43 is formed. Thereafter, etching is performed using this resist pattern as a mask, and the insulating film 12 is selectively removed to form an opening in the insulating film 12. Subsequently, a resist film (not shown) is formed on the entire surface (that is, on the insulating film 12, the exposed surface of the p-type cladding layer 42, the p-side contact layer 43, and the n-side electrode 51). A resist pattern (not shown) having an opening is prepared correspondingly. Thereafter, for example, palladium, platinum, and gold are sequentially deposited on the entire surface (that is, on the exposed surface of the p-type cladding layer 42, the p-side contact layer 43, and the resist film (not shown)), and a resist film (not shown) is formed thereon. It is removed (lifted off) together with each deposited metal. Thus, the p-side electrode 52 is formed.

After forming the p-side electrode 52, the substrate 11 is ground to a thickness of, for example, about 80 μm. Next, division is made perpendicular to the resonator direction A between the adjacent p-side contact layers 43. Thereby, resonator end faces 1a and 1b are formed. After that, reflecting mirror films (not shown) are formed on the resonator end faces 1a and 1b, respectively. Further, the semiconductor laser 1 is divided in parallel with the cavity direction A so as to correspond to the formation region. Thereby, a plurality of semiconductor lasers 1 shown in FIG. 1 are completed.

Next, the operation and effect of the semiconductor laser 1 will be described.

In the semiconductor laser 1, when a predetermined voltage is applied between the n-side electrode 51 and the p-side electrode 52, a current is injected into the active layer 30 and light emission occurs due to electron-hole recombination. This light is reflected by a reflecting mirror film (not shown), reciprocates between them, causes laser oscillation, and is emitted to the outside as a laser beam. Here, since the p-side contact layer 43 is provided in a region other than at least one end of the active layer 30 in the resonator direction A, at least one of the active layers 30 in the resonator direction A is provided. The end is a current non-injection region. Therefore, non-radiative recombination in at least one of the resonator end faces and the vicinity thereof is effectively prevented. Therefore, the rise in the temperature of the resonator end face and the vicinity thereof is suppressed, and COD is prevented.

As described above, according to the semiconductor laser 1 according to the present embodiment, the p-side contact layer 43 that makes ohmic contact with the p-side electrode 52 is placed in a region other than at least one end of the active layer 30 in the resonator direction A. Since at least one end of the active layer 30 in the resonator direction A is provided as a current non-injection region, non-emission of electrons and holes in the end face of the resonator and in the vicinity thereof is performed. Coupling can be easily prevented. Therefore, it is possible to suppress a temperature rise in the resonator end faces 1a, 1b and the vicinity thereof, and it is possible to prevent the occurrence of COD in the resonator end faces 1a, 1b and the vicinity thereof. Therefore, it is possible to easily increase the output. Further, in the present embodiment, a step is formed on the surface of the p-side electrode 52, and the vicinity of the end of the p-side electrode 52 is lower than the region corresponding to the p-side contact layer 43. When the solder is inverted and soldered to the submount, there is no danger that the excess solder will protrude to the end face and short-circuit to the active layer and further to the n-side semiconductor layer.

In particular, if the reflectivity of the reflecting mirror film formed on the end portion side which is the current non-injection region is reduced, the temperature rise of the cavity end face from which the laser beam is emitted and the vicinity thereof can be suppressed. This is more effective because COD can be prevented from being generated in the cavity end face and its vicinity.

Although FIG. 1 shows a case where the p-side electrode 52 is also provided in regions corresponding to both ends of the active layer 30 in the resonator direction A, as shown in FIG. Similarly to the above, the p-side electrode 52A may be provided in a region other than both ends of the active layer 30 in the resonator direction A. In this case, the shape of the resist pattern formed when forming the p-side electrode 52A may be changed. As described above, when the p-side electrode 52A is provided along with the p-side contact layer 43 in a region other than both ends of the active layer 30 in the resonator direction A, the p-side electrode 52 hangs down during manufacturing. A short circuit caused by contact with the n-type semiconductor layer 20 can be prevented.

[Second embodiment]
FIG. 5 shows a configuration of a semiconductor laser 2 according to the second embodiment of the present invention. The semiconductor laser 2 is the same as the first embodiment except that a high resistance layer 64 corresponding to the p-side contact layer 43 is provided at at least one end, for example, both ends, in the resonator direction A. It has the same configuration, operation and effect as described above. Therefore, here, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The high-resistance layer 64 is, for example, a layer in which the p-type semiconductor layer is damaged by an external impact or the like and has a high resistance. Therefore, also in the present embodiment, both ends of the active layer 30 in the resonator direction A are current non-injection regions.

In the semiconductor laser 2, for example, after growing a p-side contact layer 43 on the p-type cladding layer 42, at least one end of the p-side contact layer 43 in the resonator direction A by an etching method such as RIE. A portion can be manufactured in the same manner as in the first embodiment except that the high resistance layer 64 is formed by selectively damaging the portions, for example, both ends. Instead of etching, damage may be caused by irradiating oxygen, ozone or plasma to form the high-resistance layer 64. However, in this case, a part of the p-side contact layer 43 on the p-side electrode side is not cut off as shown in FIG. 5, and even if it is cut off, it is very small. According to these manufacturing methods, the high resistance layer 64 can be easily formed, and at least one end of the active layer 30 in the resonator direction can be easily formed as a current non-injection region. In particular, high-resistance layers can be formed more easily by RIE or irradiation with oxygen, ozone, or plasma.

In the present embodiment, the p-side contact layer 43 is formed in a region other than at least one end of the active layer 30 in the resonator direction A, but is shown in FIG. As described above, a part of the p-side contact layer 43 on the p-side electrode 52 side is damaged, and a high resistance is provided between the p-side contact layer 43 and the p-side electrode 52 at at least one end in the resonator direction A. A layer 64 may be provided.

[Third Embodiment]
FIG. 7 shows a configuration of a semiconductor laser 3 according to the third embodiment of the present invention. FIG. 7 shows a cross-sectional structure cut to include the p-side contact layer 43 in the resonator direction A. This semiconductor laser 3 is the same as the first embodiment except that an insulating layer 74 corresponding to the p-side contact layer 43 is provided at at least one end, for example, both ends, in the resonator direction A. It has the same configuration, operation and effect. Therefore, here, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The insulating layer 74 is made of, for example, an element capable of increasing resistance, such as oxygen, aluminum, or boron, or a nitride III-V compound semiconductor to which an n-type impurity such as silicon is added. Therefore, also in the present embodiment, both ends of the active layer 30 in the resonator direction A are current non-injection regions.

The semiconductor laser 3 is formed, for example, by growing a p-side contact layer 43 on a p-type cladding layer 42 and then irradiating it with oxygen or ozone in a radical state, or by ion implantation or impurity diffusion. Forming the insulating layer 74 by selectively adding an element capable of increasing the resistance or an n-type impurity to at least one end, for example, both ends, of the p-side contact layer 43 in the resonator direction A. Except for this, it can be manufactured in the same manner as in the first embodiment. According to these manufacturing methods, the insulating layer 74 can be easily formed, and at least one end of the active layer 30 in the resonator direction can be easily set as the current non-injection region. Above all, irradiation with oxygen or ozone makes it easier to form an insulating layer.

In the present embodiment, the p-side contact layer 43 is formed in a region other than at least one end of the active layer 30 in the resonator direction A, but is shown in FIG. As described above, an element capable of increasing the resistance or an n-type impurity is selectively added to a part of the p-side contact layer 43 on the p-side electrode 52 side, so that at least one end in the resonator direction A is formed. An insulating layer 74 may be provided between the p-side contact layer 43 and the p-side electrode 52.

[Fourth Embodiment]
FIG. 9 shows a configuration of a semiconductor laser 4 according to the fourth embodiment of the present invention. The semiconductor laser 4 includes a p-side contact layer 83 and an insulating film 92 having different shapes from the p-side contact layer 43 and the insulating film 12 of the semiconductor laser 1 according to the first embodiment, respectively. Except for this, the other configuration is the same as that of the semiconductor laser 1. Therefore, here, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The p-side contact layer 83 extends in the resonator direction A, and is also provided in at least one end of the active layer 30 in the resonator direction A, for example, a region corresponding to both ends. The insulating film 92 is provided adjacent to the p-side semiconductor layer 80 and the n-side contact layer 21, and has an opening 92a corresponding to another region except at least one end of the active layer 30 in the resonator direction A. have. Thus, the ohmic contact between the p-side contact layer 83 and the p-side electrode 52 is limited to a region other than at least one end of the active layer 30 in the resonator direction A. Therefore, also in the present embodiment, at least one end of the active layer 30 in the resonator direction A is a current non-injection region. The width of the current non-injection region in the resonator direction A is preferably within 100 μm, more preferably in the range of 10 μm to 50 μm, as in the first embodiment. Note that an opening corresponding to the n-side contact layer 21 is also provided in the insulating film 92, as in the first embodiment.

半導体 The semiconductor laser 4 having such a configuration can be manufactured as follows.

First, in the same manner as in the first embodiment, an n-type semiconductor layer 20, an active layer 30, and a p-type semiconductor layer 80 are sequentially grown on, for example, the c-plane of the substrate 11, and the upper part of the p-type After forming the side contact layer 73 into a narrow band, the n-side contact layer 21 is exposed on the surface. Next, after an insulating film 92 made of silicon dioxide is formed on the entire surface by, for example, a vapor deposition method, the n-side electrode 51 is formed in the same manner as in the first embodiment.

Subsequently, an opening 92a is formed in the insulating film 92 so as to correspond to at least one end of the active layer 30 in the resonator direction A, for example, a region other than both ends. After that, the p-side electrode 52 is formed in the same manner as in the first embodiment. Subsequent steps are the same as in the first embodiment.

The operation of the semiconductor laser 4 is the same as that of the semiconductor laser 1 according to the first embodiment.

As described above, according to the semiconductor laser 4 according to the present embodiment, the insulating film 92 having the opening 92 a corresponding to the other region except the both ends of the active layer 30 in the resonator direction A is formed as the p-type semiconductor layer 80. The p-side electrode 52 and the p-side contact layer 83 are in ohmic contact with each other through the opening 92a of the insulating film 92, and at least one end of the active layer 30 in the resonator direction A is not injected with current. Since the region is defined as in the first embodiment, non-radiative recombination of electrons and holes in the cavity end face and in the vicinity thereof can be easily prevented, as in the first embodiment.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment and can be variously modified. For example, in the first embodiment, only the p-side contact layer 43 is provided corresponding to the other region except at least one end of the active layer 30 in the resonator direction A. In addition to the layer 43, at least a part of the p-type cladding layer 42 may be provided corresponding to another region except at least one end of the active layer 30 in the resonator direction A. Also in this case, the effects of the present invention can be obtained without deteriorating the characteristics of the semiconductor laser 1. Similarly, in the second embodiment, only the p-side contact layer 43 is damaged, and in the third embodiment, an element or n-type element capable of increasing the resistance only in the p-side contact layer 43 is used. Although the impurity is added, at least a part of the p-type cladding layer 42 may be damaged in addition to the p-side contact layer 43, or they may be added.

In the above embodiment, the n-side contact layer 21, the n-type cladding layer 22, the n-type guide layer 23, the active layer 30, the p-type guide layer 41, the p-type clad layer 42, and the p-side contact layers 43 and 83 are formed. The constituent semiconductors have been described with specific examples, but each of these layers is made of another group III-V nitride semiconductor containing at least one of the group 3B elements and nitrogen. Is also good.

Further, in the above embodiment, the n-side contact layer 21, the n-type cladding layer 22, the n-type guide layer 23, the active layer 30, the p-type guide layer 41, the p-type clad layer 42, and the p-side contact layers 43 and 83 are formed. Although the layers are sequentially stacked, the present invention can be similarly applied to a semiconductor laser having another structure. For example, the n-type guide layer 23 and the p-type guide layer 41 do not have to be provided, and a deterioration preventing layer may be provided between the active layer 30 and the p-type guide layer 41. Further, in the above-described embodiment, the current is confined by forming a part of the p-type cladding layer 42 and the p-side contact layers 43 and 83 in a narrow band shape. However, the current may be confined by another structure. Good. In the above embodiment, the ridge waveguide type semiconductor laser combining the gain waveguide type and the refractive index waveguide type has been described as an example. The same can be applied to a semiconductor laser of a type.

In the above embodiment, the substrate 11 is made of sapphire, but is made of another material such as gallium nitride, silicon carbide (SiC), spinel (MgAl ₂ O ₄ ), or gallium arsenide (GaAs). You may do so.

In addition, in the above embodiment, the case where the n-type semiconductor layer 20, the active layer 30, and the p-type semiconductor layers 40, 60, 70, 80 are formed by the MOCVD method has been described. Alternatively, it may be formed by another vapor deposition method. Note that the hydride vapor phase epitaxy refers to a vapor phase epitaxy in which halogen contributes to transport or reaction.

FIG. 1 is a perspective view illustrating a configuration of a semiconductor laser according to a first embodiment of the present invention, partially cut away. FIG. 2 is a sectional view illustrating a manufacturing process of the semiconductor laser illustrated in FIG. 1. FIG. 3 is a cross-sectional view illustrating a manufacturing process following FIG. 2. FIG. 9 is a perspective view illustrating a configuration of a semiconductor laser according to a modification example of the semiconductor laser illustrated in FIG. 1. FIG. 9 is a perspective view illustrating a configuration of a semiconductor laser according to a second embodiment of the present invention, partially cut away; FIG. 6 is a perspective view showing a configuration of a semiconductor laser according to a modification of the semiconductor laser shown in FIG. FIG. 13 is a perspective view illustrating a configuration of a semiconductor laser according to a third embodiment of the present invention. FIG. 9 is a perspective view illustrating a configuration of a semiconductor laser according to a modification example of the semiconductor laser illustrated in FIG. FIG. 13 is a perspective view illustrating a configuration of a semiconductor laser according to a fourth embodiment of the present invention, with a part thereof broken away.

Explanation of reference numerals

1, 2, 3, 4 ... semiconductor laser, 1a, 1b ... cavity facet, 11 ... substrate, 12, 92 ... insulating film, 20 ... n-type semiconductor layer, 21 ... n-side contact layer, 22 ... n-type clad layer , 23 ... n-type guide layer, 30 ... active layer, 40, 60, 70, 80 ... p-type semiconductor layer, 41 ... p-type guide layer, 42 ... p-type cladding layer, 43, 83 ... p-side contact layer, 51 ... n-side electrode, 52, 52A ... p-side electrode, 64 ... high-resistance layer, 74 ... insulating layer, 92a ... opening, A ... resonator direction

Claims (5)

An n-type semiconductor layer, an active layer, and a p-type semiconductor layer each made of a nitride III-V compound semiconductor containing at least one of the group 3B elements and at least nitrogen (N) of the group 5B element are sequentially formed. The semiconductor laser is stacked and an n-side electrode is in ohmic contact with the n-type semiconductor layer, and a p-side electrode is in ohmic contact with the p-type semiconductor layer, wherein the p-type semiconductor layer is
A p-side contact layer provided corresponding to a region excluding at least one end of the active layer in the resonator direction and in ohmic contact with the p-side electrode;
An underlayer provided between the p-side contact layer and the p-side electrode, in contact with the p-side contact layer, and provided so as to correspond to an entire region of the active layer;
At least one end in the resonator direction of the active layer is a current non-injection region due to an insulating layer or a high resistance layer interposed between the p-side electrode and the base layer,
In addition, the thickness of the insulating layer or the high-resistance layer in the stacking direction is formed to be thinner than the p-side contact layer, and near the end of the surface of the p-side electrode is lower than the region corresponding to the p-side contact layer A semiconductor laser having a step. 2. The semiconductor laser according to claim 1, wherein the width of the current non-injection region in the resonator direction is within 100 μm. The high resistance layer is formed by forming the p-side contact layer up to the vicinity of the cavity facet and then selectively removing the vicinity of the cavity facet by dry etching (RIE) to cause damage. The semiconductor laser according to claim 1, wherein The p-side contact layer is formed of p-type gallium nitride (GaN), and the p-side electrode is formed of palladium (Pd), platinum (Pt), and palladium (Pt) from the p-side contact layer and the insulating layer or the high-resistance layer side. 2. The semiconductor laser according to claim 1, having a structure in which gold (Au) is sequentially laminated. 2. The semiconductor laser according to claim 1, wherein the underlayer is formed of p-type aluminum gallium nitride (AlGaN).

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