JPH11284280A - Semiconductor laser device, its manufacture and manufacture of iii-v compound semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively blocking injection of a current to an end surface, by performing solid-phase diffusion of dopant from a III-V compound semiconductor layer containing Zn or the like of high concentration. SOLUTION: An N-type GaAs buffer layer 2, an N-type In0.5 (Ga0.3 Al0.7 )0.5 P clad layer 3, an active region 4, a P-type In0.5 (Ga0.3 Al0.7 )0.5 P clad layer 5, a P-type In0.5 Ga0.5 P easy conduction layer 6 and an N-type GaAs cap layer 7 are formed in order on an N-type GaAs substrate 1. Stripe-shaped SiO2 8 is deposited in parallel to an end surface of a resonator, and the cap layer 7 and the easy conduction layer 6 are etched by using the SiO2 8 as a mask. A P-type GaAs layer 9 doped with Zn is selectively grown and annealed, and Zn is diffused to the intermediate point of the N-type In0.5 (Ga0.3 Al0.7 )0.5 P clad layer 3. When the Zn concentration of the P-type GaAs layer 9 is at least 2×10<18> cm<-3> and the thickness of the layer is at least 0.2 μm, a window region 10 which acts excellently can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device and a method for manufacturing the same, and a method for manufacturing a III-V compound semiconductor device. More specifically, the present invention relates to a semiconductor laser device having a high output operation, particularly a semiconductor laser device as a visible light semiconductor laser device suitable for use as a light source of an optical information processing device such as a digital video disk or a magneto-optical disk. The present invention relates to a method for manufacturing the same and a method for manufacturing a group III-V compound semiconductor device.

[0002]

2. Description of the Related Art Group III-V compound semiconductor devices have been widely used as optical devices such as light emitting devices and light receiving devices or various electronic devices such as field effect transistors and bipolar transistors. In the following description,
Of these, a semiconductor laser will be described as an example.

In recent years, a visible light semiconductor laser having a light output of 30 mW or more has been required as a light source for writing on an optical disk such as a MO (Magnetic-optical) disk or a DVD (Digital-versatile-Disk). In such a high-power semiconductor laser, an increase in the optical output density at the emission end face of the semiconductor laser causes a problem in that optical damage (Catastrophic Optical Damage: COD) occurs in which the semiconductor crystal melts and defects multiply. This COD is generated because the laser light is absorbed at the emission end face of the semiconductor laser to generate carriers, and when the carriers recombine, the number of cycles of generating heat is increased. Therefore, if a semiconductor layer having a band gap energy larger than the energy of the laser light is provided on the end face of the semiconductor laser, the emission end face becomes transparent to the laser light, and the light absorption at the emission end face does not occur. Will not happen. Such a laser is called a “window structure laser” and is a necessary structure for a high-power semiconductor laser.

[0004] Documents disclosing such a window structure laser manufacturing method include, for example, the IEEE Journal of Japan.
f Quantum Electronics, Vo
l. 29, no. 6, p1874-1879 (199)
3) can be mentioned. According to the method disclosed in this document, ZnO is selectively deposited in a region where a window structure is to be formed, and Zn (zinc) is diffused from ZnO to a cladding layer below an active layer of the semiconductor laser wafer by subsequent annealing. Then, the active layer portion is mixed with the cladding layer to increase the band gap energy of the diffusion portion with respect to the non-diffusion portion, and this region is used as a window region.
In this method, the diffusion depth of Zn is determined only by the annealing time and the annealing temperature.

[0005]

However, if the annealing temperature is increased or the annealing time is increased in order to diffuse Zn more deeply at the time of forming the window region, the Z
Zn is diffused from the p-type cladding layer of the semiconductor laser doped with n into the active layer, and Zn is diffused into the active layer other than the window region. If Zn diffuses into the active layer, there is a problem that deterioration occurs during operation and long-term reliability is deteriorated.

[0006] This problem becomes more serious as the thickness of the cladding layer of the semiconductor laser increases. That is, as the cladding layer is thicker, a high-temperature and long-time thermal diffusion treatment is required to introduce Zn from the wafer surface.

On the other hand, in order to prevent the end face from being deteriorated due to the high output operation, an end face current non-injection structure for preventing a current from flowing to the light emitting end face portion of the semiconductor laser has been attempted. In the above-mentioned literature, a current blocking layer is provided on both sides of a ridge stripe serving as a laser resonator. In addition to this, in order to make the window structure portion a current non-injection structure, a window structure portion is provided. A current blocking layer made of an n-type GaAs layer is provided thereon to block the current. That is, in this structure, the current block is performed by a p-type / n-type / p-type stacked structure. When blocking current with such a structure, the n-type layer should be at least 0.5 μm.
It is necessary to laminate with a film thickness of at least m. Therefore, p-type G
After the growth of the aAs layer, irregularities are formed on the upper surface of the window region. As a result of such unevenness, a problem occurs when the semiconductor laser is mounted on the heat sink from the upside down.

In addition, since the n-type GaAs layer is selectively grown only in the window region, there is another problem that the number of steps such as mask alignment increases and the process becomes complicated.

[0009] The various problems as described above also occur in many III-V compound semiconductor devices other than semiconductor lasers. That is, the process of introducing Zn from the wafer surface by diffusion is often used also in the light receiving element and various electronic devices, and the above-described problem has occurred.

The present invention has been made in view of such a problem. That is, the purpose is that Zn can be diffused more easily than before, the process steps are simplified,
Semiconductor laser device capable of effectively blocking current injection to end face, method of manufacturing the same, and III
-To provide a method for manufacturing a Group V compound semiconductor device.

[0011]

That is, a semiconductor laser device according to the present invention comprises a compound semiconductor substrate of a first conductivity type, a cladding layer of a first conductivity type, an active layer, and a cladding layer of a second conductivity type. A second conductive type contact layer having a band gap smaller than the second conductive type clad layer, and a band gap smaller than the second conductive type clad layer and a band gap smaller than the second conductive type contact layer. A semiconductor laser device that emits a laser beam from an end face, wherein the end face and the vicinity thereof include a second conductive type clad layer and the contact layer. Are stacked adjacent to each other, and a current is suppressed by a hetero barrier at an interface between the cladding layer of the second conductivity type and the contact layer. In portions other than near, the second
The present invention is characterized in that the current-carrying layer is interposed between the conductive-type cladding layer and the contact layer to promote current-carrying.

Here, the end face of the semiconductor laser device and the vicinity thereof are a window region formed of a compound semiconductor having a band gap larger than that of the active layer in other portions, and the window region is formed of the laser beam. By having a band gap corresponding to energy higher than light energy, the laser light is not absorbed in the window region.

The active layer has a multi-quantum structure including a well layer having a smaller band gap than the clad layer and a barrier layer having a smaller band gap than the clad layer and a larger band gap than the well layer. It has a well structure.

Alternatively, the active layer has a multi-quantum structure including a well layer having a smaller band gap than the clad layer and a barrier layer having a smaller band gap than the clad layer and a larger band gap than the well layer. A well structure, and a light guide layer having a band gap larger than the effective band gap of the multiple quantum well structure and smaller than the cladding layer.

Further, the second conductivity type cladding layer is characterized in that it has a ridge stripe which is configured to have a thick layer in a strip shape along the direction in which the laser light is emitted.

Further, a current blocking layer of the first conductivity type is laminated on both sides of the ridge stripe of the cladding layer of the second conductivity type, respectively.

Further, the compound semiconductor substrate is made of GaAs.
Wherein the first conductivity type cladding layer, the active layer, and the second conductivity type cladding layer are made of an InGaAlP-based material.

On the other hand, a method of manufacturing a semiconductor laser device according to the present invention is a method of manufacturing a semiconductor laser device that emits laser light from an end face, wherein a first conductive type cladding is formed on a III-V compound semiconductor substrate. A layer, an active layer, a second conductivity type clad layer, and a step of forming a wafer in which a second conductivity type second layer having a smaller band gap than the second conductivity type cladding layer is sequentially stacked. A step of selectively etching away the current-carrying layer immediately above the end face and the vicinity thereof to expose the second conductivity-type cladding layer on the surface; and Forming a second conductive type contact layer having a band gap smaller than that of the easy-to-conduct layer on the easy-to-conduct layer.

Alternatively, a method of manufacturing a semiconductor laser device according to the present invention is a method of manufacturing a semiconductor laser device that emits laser light from an end face, wherein a cladding of a first conductivity type is formed on a III-V compound semiconductor substrate. A layer, an active layer, a second conductivity type clad layer, and a step of forming a wafer in which a second conductivity type second layer having a smaller band gap than the second conductivity type cladding layer is sequentially stacked. Forming a mask having an opening on the easy conducting layer;
Forming a p-type III-V compound semiconductor layer doped with 10 ¹⁸ cm ^-3 or more; and forming the second conductive type cladding layer, the active layer, and the first conductive layer from the p-type III-V compound semiconductor layer. A step of sequentially diffusing Zn into a mold cladding layer, and a step of forming the end face by dividing the wafer so as to cross the portion where the opening of the mask was formed. Features.

Alternatively, a method of manufacturing a semiconductor laser device according to the present invention is a method of manufacturing a semiconductor laser device that emits laser light from an end face, wherein a first conductivity type cladding is formed on a III-V compound semiconductor substrate. A layer, an active layer, a second conductivity type clad layer, and a step of forming a wafer in which a second conductivity type second layer having a smaller band gap than the second conductivity type cladding layer is sequentially stacked. Forming a mask having an opening on the conductive layer, and selectively removing the conductive layer by etching the opening of the mask to expose the second conductive type cladding layer; And a p-type doped with at least 2 × 10 ¹⁸ cm ⁻³ of Zn on the surface of the cladding layer of the second conductivity type exposed at least in the opening of the mask.
Forming a group III-V compound semiconductor layer and sequentially diffusing Zn from the p-type group III-V compound semiconductor into the cladding layer of the second conductivity type, the active layer and the cladding layer of the first conductivity type; And a step of forming the end face by dividing the wafer so as to cross the portion of the mask where the opening is formed.

Here, the step of diffusing is performed by performing an annealing treatment in an atmosphere containing hydrogen, nitrogen, or a group V element constituting the p-type III-V compound semiconductor layer. A step of sequentially diffusing Zn from the III-V compound semiconductor into the second conductivity type cladding layer, the active layer, and the first conductivity type cladding layer.

The thickness of the p-type III-V compound semiconductor layer is 0.2 μm or more.

Further, the p-type III-V compound semiconductor layer is made of GaAs.

Further, the mask is made of any one of silicon oxide, silicon nitride, and aluminum oxide.

Alternatively, the mask is made of a compound semiconductor.

Further, the mask made of the compound semiconductor is characterized by being undoped or doped with an n-type impurity.

Further, the thickness of the mask is at least half the thickness of the cladding layer of the second conductivity type.

Further, the mask is made of GaAs.

The p-type III-V compound semiconductor layer is formed by metal organic chemical vapor deposition, molecular beam epitaxy,
It is characterized by being performed by any one of a hydride vapor phase epitaxy method, a chloride vapor phase epitaxy method, and a liquid layer epitaxy method.

On the other hand, a method of manufacturing a group III-V compound semiconductor device of the present invention comprises the steps of forming a mask having an opening on a wafer, and forming a mask on at least the surface of the wafer exposed at the opening of the mask. Zn is 2 × 10 ¹⁸ cm
Forming a p-type III-V compound semiconductor layer doped with ^-3 or more, and diffusing Zn from the p-type III-V compound semiconductor into the wafer. .

Here, the step of diffusing includes a step of diffusing the Zn by performing an annealing process.

Further, the annealing treatment is performed in an atmosphere containing hydrogen, nitrogen, or a group V element constituting the p-type group III-V compound semiconductor layer.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when manufacturing a III-V compound semiconductor device, Zn
A group III-V compound semiconductor layer containing a high concentration of such a dopant is provided, and the dopant is solid-phase diffused from this layer to introduce Zn into a predetermined place of the wafer.
This makes it possible to control the amount of dopant diffusion much more precisely than in the past.

For example, when the present invention is applied to a semiconductor laser, a group III-V compound semiconductor layer containing Zn at a high concentration is provided immediately above the end face of the semiconductor laser, and solid phase diffusion of Zn is performed from this layer. Thereby, the active layer in the end face emission region is disordered, so that the window region can be formed with high controllability.

Further, in the present invention, by forming a current blocking structure using a hetero-barrier above this window region, a high-performance end face non-injection type window structure laser can be realized.

Hereinafter, embodiments of the present invention will be described with reference to examples.

(Embodiment 1) FIGS. 1 and 2 are schematic process diagrams showing a method of manufacturing a semiconductor laser according to the present invention. That is, FIG. 1 illustrates a case where the present invention is applied to an InGaAlP-based visible light semiconductor laser.

According to the present invention, as shown in FIG. 1A, an n-type GaAs doped with, for example, Si is formed on an n-type GaAs substrate 1 by, for example, a metal organic chemical vapor deposition (MOCVD) method. Buffer layer 2, for example, n-type In _0.5 (Ga _0.3 Al
_0.7 ) _0.5 P cladding layer (n = 3 to 4 × 10 ¹⁷ cm ⁻³ )
3. Active region 4, for example, a film thickness doped with Zn.
A 7 μm p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer (p = 9 × 10 ¹⁷ cm ⁻³ ) 5, for example, a Zn-doped 50 nm-thick p-type In _0.5 Ga _0.5 P conducting layer 6, For example, 50 nm thick n-type G doped with Si
The aAs cap layer 7 is sequentially formed.

Here, the active region 4 is formed, for example, as shown in FIG.
As shown in FIG. 3, a 25 nm thick In _0.5 (Ga _0.5 Al
_0.5 ) _0.5 P First light guide layer 16, 6.5 nm thick In
_0.65 Ga _0.35 P well layer 17 and 4 nm thick In _0.5 (G
a _0.5 Al _0.5 ) _0.5 P barrier layer 18 and an MQW active layer 20 and a 25 nm thick In _0.5 (Ga _0.5 A).
l _0.5 ) _0.5 P The second light guide layer 19 may be used.

Next, by depositing a stripe-shaped SiO ₂ 8 As example a thickness 200nm to have an opening of 20μm from parallel to example end face cavity end face of the semiconductor laser, the stripe-shaped SiO ₂ 8 as a mask, for example, n-type GaAs by wet etching or the like.
The s cap layer 7 and the p-type In _0.5 Ga _0.5 P current easily layer 6 is etched.

Next, as shown in FIG. 1B, a window region 10 is formed. Specifically, for example, a p-type GaAs layer 9 doped with Zn at 2 × 10 ¹⁸ cm ⁻³ or more is selectively grown by a crystal growth method such as an MOCVD method, and then annealing is performed to add Zn to the p-type GaAs layer. 9 to n-type I
The n _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 3 is diffused partway, and a window region 10 in which Zn is diffused is selectively formed below the opening of SiO ₂ 8.

The procedure of Zn diffusion will be described in more detail by taking the case of using the MOCVD method as an example. First, at a growth temperature of 650 ° C., TMG (trimethylgallium), DMZ (dimethylzinc), and AsH ₃
The type GaAs layer is grown, for example, to 1.5 μm. Where Z
The n concentration is set so as to be 2 × 10 ¹⁸ cm ⁻³ . Thereafter, supply of TMG, DMZ, and AsH ₃ is stopped at the growth temperature, and annealing is performed for 20 minutes in an H ₂ atmosphere. During this time, Zn is transferred from the p-type GaAs layer 9 to the n-type In _0.5 (Ga
_0.3 Al _0.7 ) _0.5 P is diffused halfway through the cladding layer 3. By this diffusion, the MQW active layer 20 and the light guide layer 1
The active regions 6 and 19 are adjacent p-type In
_0.5 (Ga _0.3 Al _0.7 ) _0.5 P clad layer 5 and n-type I
_{n 0.5 (Ga 0 .3 Al 0.7} ) and 3 and disordering _0.5 P clad layer, the effective band gap becomes a window region increases as a result.

In the case of the present embodiment, the photoluminescence (PL) wavelengths of the Zn diffusion region and the region under which Zn is not diffused under SiO ₂ 8 in the active region 4 are respectively:
630 nm and 680 nm, and 50 nm in the Zn diffusion region.
It has been found that the wavelength can be shortened to nm, and that the film sufficiently functions as a window region.

FIG. 3 is a depth profile of the ionized impurity concentration measured from the wafer surface by the CV method. When the ionized impurity is mainly Zn, it is measured as p-type, and when the ionized impurity is mainly Si (silicon), it is measured as n-type. Therefore, it can be considered that the profile of the p-type measurement point corresponds to the Zn diffusion profile. In the figure, the solid line is the profile of the p-type ionized impurity concentration measured in the portion where Zn is diffused, and the broken line is the profile of the p-type carrier concentration measured in the portion where Zn is not diffused. Z
In the non-diffusion region of n, the impurity concentration of p-type ionization of the p-type cladding layer is almost the same as that before the diffusion treatment, and the ionization impurity concentration of the active region is extremely low and close to the measurement limit. On the other hand, the ionized impurity concentration of the p-type cladding layer in the diffusion region increases from 9 × 10 ¹⁷ cm ⁻³ of the ionized impurity concentration in the non-diffusion region to 1.3 × 10 ¹⁸ cm ⁻³ , and the active region is increased. In No. 4, the concentration of the impurity ionized to p-type is greatly increased as compared with the non-diffusion region. The position where the impurity concentration ionized in the n-type cladding layer 3 is inverted from p-type to n-type is about 0.2 μm in the diffusion region (black square in the figure) as compared with the non-diffusion region (white circle in the figure). It is getting deeper. That is, it was confirmed that the diffusion of Zn in the diffusion region reached at least a depth of 0.2 μm in the n-type cladding layer.

In this Zn diffusion process, the p-type GaAs layer 9
As the growth temperature is increased, the film thickness is increased, the Zn concentration is increased, or the H ₂ annealing time after growing the p-type GaAs layer 9 is increased, or the annealing temperature is increased. The more you do, the more Z
n diffuses deeper into the wafer. As a result of the study by the present inventors, the Zn concentration of the p-type GaAs layer 9 was 2 × 10 ¹⁸ c
When the layer thickness is not less than m ^-3 and the layer thickness is not less than 0.2 μm, the window region 10 which works well can be formed.

The setting of each of the above parameters in this embodiment is merely an example, and the above parameters may be determined as appropriate according to the type and thickness of the semiconductor layer for diffusing Zn and the depth for diffusing Zn.

In the case where Zn in the p-type cladding layer 5 in the non-diffusion region is easily diffused into the n-type cladding layer 3, the annealing temperature and time parameters should not be increased among the above parameters. It is desirable to increase the Zn concentration in the p-type GaAs layer 9 to deepen the diffusion of Zn. Alternatively, the thickness of the p-type GaAs layer should be increased.

In this embodiment, after growing the p-type GaAs layer, H ₂ annealing is performed at the same temperature as the growth temperature. However, the annealing temperature may be higher than the growth temperature. Also, instead of a hydrogen atmosphere, a nitrogen gas atmosphere,
Annealing may be performed in an atmosphere containing a group V element such as sH ₃ .

Further, in this embodiment, a p-type GaAs layer doped with Zn at a high concentration is used as a Zn diffusion source. However, the same effect can be obtained not only with GaAs but also with other III-V compound semiconductors. can get. Also in this case, the p-type
Annealing after growing the III-V compound semiconductor may be performed in a hydrogen atmosphere, a nitrogen atmosphere, or a group V material atmosphere.

In this embodiment, the p-type GaAs layer is grown by MOCVD, but the same effect can be obtained by molecular beam epitaxy (MBE) or other crystal growth methods. In the case of the MBE method, annealing after the growth of the p-type GaAs layer may be performed in an As (arsenic) atmosphere or in a vacuum.

Further, in order to diffuse impurities in a solid phase,
In some cases, it is not necessary to separately provide an annealing step. That is, during the growth of the p-type III-V compound semiconductor, the contained p-type impurity may diffuse into the underlying semiconductor layer in a solid phase. In such a case, the p-type impurity can be diffused in a solid phase without performing a separate annealing step after growing the p-type III-V compound semiconductor.

Next, as shown in FIG.
The aAs layer 9 is removed by etching, and the Zn diffusion region 10 of the p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P clad layer 5 is exposed in the opening of the SiO ₂ 8.

Thereafter, as shown in FIG.
After removing the O ₂ 8 and exposing the n-type GaAs 7, in order to form a ridge stripe serving as a resonator, for example, the width 4.
A 5 μm-thick, 200-nm-thick striped SiO ₂ 11 is formed so as to be orthogonal to the striped opening of n-type GaAs 7.

Next, as shown in FIG. 1 (e), the n-type GaAs 7 and the p-type In _0.5 Ga _0.5 P conductive layer 6 are removed by etching using the striped SiO ₂ 11 as a mask.

Next, as shown in FIG. 1 (f), and a stripe-shaped SiO ₂ 11 as a mask, P-type an In _0.5 (Ga
_0.3 Al _0.7 ) _0.5 P clad layer 5 is formed in a ridge stripe shape. As the shape, for example, a ridge width of about 5
μm, ridge thickness 1.7 μm, ridge side thickness 0.
It is formed to 25 μm.

Next, as shown in FIG.
aAs (n = 2 × 10 ¹⁸ cm ⁻³ )
Selectively grow on the side surface of the ridge with a thickness of μm.

Next, as shown in FIG. 2B, the striped SiO ₂ 11 is removed by etching.

Further, as shown in FIG.
By removing aAs7 by etching, p-type In _0.5 in (Ga _0.3 Al _{0.7) 0.5} P cladding layer 5 of the ridge on the stripe, p-type to the Zn diffusion region and the opening I
The n _0.5 Ga _0.5 P conductive layer 6 is exposed.

Thereafter, as shown in FIG.
aAs contact layer (p = 2 × 10 ¹⁸ cm ⁻³ ) 13
μm, AuZn / Au14 is formed as a p-side electrode, and AuGe / Au15 is formed as an n-side electrode. Furthermore, the semiconductor laser is completed by dividing the wafer by a method such as cleavage, scribing, dicing, or dry etching, and forming an end surface from which laser light is emitted.

FIG. 2E is a partial cross-sectional perspective view of the semiconductor laser manufactured according to this embodiment. As can be seen from the figure, a window region 10 formed by Zn diffusion is formed on the light emitting end face of the laser, and a p-type In _0.5
Ga _0.5 P Direct p-type In _0.5 (G
a _0.3 Al _0.7 ) _0.5 P clad layer 5 and p-type GaAs contact layer 13 are in contact with each other. For this reason, in this portion, the current is cut off by the hetero barrier because the band gap difference between the two layers is large. On the other hand, on the ridge stripe other than the Zn diffusion region 10, p-type In _0.5 (Ga _0.3 Al
_0.7 ) _0.5 P cladding layer 5 and p-type GaAs contact layer 1
3 having an intermediate band gap energy between 3
_The presence of the _0.5 Ga _0.5 P conduction layer 6 provides a structure in which current flows. In this manner, a window region is formed on the light emitting end surface by the diffusion of Zn, and an end-face non-injection type window structure in which no current flows in this window region is obtained.

The end face non-injection type window structure semiconductor laser obtained by this embodiment oscillates at an oscillation wavelength of 680 nm at a resonator length of 800 μm, a stripe width of 5 μm, a front surface reflectivity of 10%, and a back surface reflectivity of 90%. It was confirmed that no COD was generated up to 150 mW.

In this embodiment, the active region 4 is formed of the MQW active layer 20 and the light guide layers 16 and 19, but any semiconductor layer having a band gap energy smaller than that of the cladding layer may be used. Often, not only the MQW active layer but also a single-layer active layer can increase the band gap energy due to Zn diffusion and achieve the same effect.

In this embodiment, the oscillation wavelength is 680 nm.
m, but the oscillation wavelength can be adjusted by appropriately selecting the structure of the MQW active layer 20. In any wavelength band, the active layer portion is at least P
If the wavelength is 20 nm or more as the L wavelength, the wavelength can be shortened and can function as a window region.

In this embodiment, the p-type Ga doped with Zn 2 × 10 ¹⁸ cm ⁻³ or more is formed in the opening of SiO ₂ 8.
The As layer 9 is selectively grown, and then an annealing process is added.
Zn is transferred from the p-type GaAs layer 9 to the n-type In _0.5 (Ga _0.3 Al
_0.7 ) Before the Zn diffusion region 10 is selectively formed in the opening portion of the SiO ₂ 8 by diffusing it to the middle of the _0.5 P cladding layer 3, the p-type In _0.5 Ga _0.5 P easy conducting layer in the opening portion of the SiO ₂ 8 is formed. 6 was etched, but this order may be reversed.

(Embodiment 2) Next, a second embodiment of the present invention will be described. 4 and 5 show a second embodiment according to the present invention.
FIG. 5 is a schematic process chart illustrating a method for manufacturing a semiconductor laser of FIG. That is, FIG. 1 illustrates a case where the present invention is applied to an InGaAlP-based visible light semiconductor laser.

In this embodiment, as in the first embodiment, first, as shown in FIG. 4A, an n-type GaAs substrate 1 is formed on the n-type GaAs substrate 1 by metal organic chemical vapor deposition (MOCVD).
For example, an n-type GaAs buffer layer 2 doped with Si, for example, an n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P clad layer (n = 3 to 1.7 μm) doped with Si.
4 × 10 ¹⁷ cm ⁻³ ) 3, active region 4, for example, a 1.7 μm-thick p-type In _0.5 (Ga _0.3 Al doped with Zn)
_0.7 ) _0.5 P cladding layer (p = 9 × 10 ¹⁷ cm ⁻³ ) 5, for example, a 50 nm-thick p-type In _0.5 doped with Zn.
A Ga _0.5 P conductive layer 6, for example, an n-type GaAs cap layer 7 doped with Si and having a thickness of 1.7 μm is sequentially formed.

Here, the active region 4 is formed, for example, as shown in FIG.
As shown in FIG. 3, a 25 nm thick In _0.5 (Ga _0.5 Al
_0.5 ) _0.5 P First light guide layer 16, 6.5 nm thick In
_0.65 Ga _0.35 P well layer 17 and 4 nm thick In _0.5 (G
a _0.5 Al _0.5 ) _0.5 P barrier layer 18 and an MQW active layer 20 and a 25 nm thick In _0.5 (Ga _0.5 A).
l _0.5 ) _0.5 P The second light guide layer 19 may be used.

This embodiment is different from the first embodiment in that the thickness of the n-type GaAs cap layer 7 is formed to be at least half the thickness of the p-type cladding layer 5 or more. is there. In the present embodiment, as an example, the cladding layer 9 is used.
And the same thickness.

Thereafter, in the same manner as in the first embodiment, for example, 20 μm from the end face in parallel with the end face of the resonator of the semiconductor laser.
SiO ₂ 8 on the stripe is deposited so as to have a thickness of, for example, 200 nm so as to have an opening of the n-type GaAs cap layer 7 and p-type by wet etching or the like using the SiO ₂ 8 on the stripe as a mask. The type In _0.5 Ga _0.5 P easy-to-conduct layer 6 is etched.

Subsequently, as shown in FIG. 4B, the striped SiO ₂ 8 was removed by etching, and the MO
Zn is deposited at 2 × 10 ¹⁸ c by a crystal growth method such as a CVD method.
A p-type GaAs layer 9 doped with m ⁻³ or more is grown, and then annealing is applied to diffuse Zn from the p-type GaAs layer 9 to a point in the n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 3. . Here, the difference from the first embodiment is that the p-type GaAs layer 9 having a high concentration of Zn is deposited also on the n-type GaAs cap layer 7, so that Zn is changed from the p-type GaAs layer 9 to n. The point is that it also diffuses into the type GaAs cap layer 7.

However, if the n-type GaAs cap layer 7 has at least half the thickness of the p-type cladding layer 5, the diffusion of Zn stops in the p-type cladding layer.
The active region 4 under the type GaAs cap layer 7 does not cause mixed crystal due to Zn diffusion.

In the case of the present embodiment, the n-type GaAs cap layer 7 has the same thickness as the p-type cladding layer 5, so that
The diffusion of Zn almost stops in the n-type GaAs cap layer 7, and as a result, as in the first embodiment, the Zn diffusion region 1
0 is selectively formed in the opening of the n-type GaAs cap layer 7.

In the case of the present embodiment, the Z
The photoluminescence (PL) wavelengths of the n-diffusion region and the region where Zn is not diffused below the n-type GaAs cap layer 7 are 630 nm and 680 nm, respectively, and as in the first embodiment, the photoluminescence (PL) wavelength is as short as 50 nm in the Zn-diffusion region. It is possible to realize a wavelength, and to sufficiently function as a window region. At this time, the profile of the ionized impurity concentration measured by the CV method was similar to that shown in FIG.

Also in the present embodiment, the parameters for determining the Zn diffusion depth are the same as in the first embodiment. However, a major difference from the first embodiment is that Zn is diffused from the p-type GaAs layer 9 to the n-type GaAs cap layer 7, so that the selectivity of Zn diffusion is limited to the n-type GaAs cap layer 9.
Is strongly dependent on the thickness of the substrate. The greater the thickness of the n-type GaAs cap layer 9, the stronger the selectivity of Zn diffusion. The thickness of the n-type GaAs cap layer 9 must be at least half the thickness of the p-type cladding layer 5 or more.

Subsequently, as shown in FIG. 4C, the p-type GaAs layer 9 and the n-type GaAs 7 are removed by etching, and a Zn diffusion region is formed in the opening of the p-type In _0.5 Ga _0.5 P easy-to-conduct layer 6. Expose 10

Thereafter, as shown in FIG. 4D, in order to form a ridge stripe serving as a resonator, for example, the width of the ridge stripe is 4.times.
A stripe-shaped SiO ₂ 11 having a thickness of 5 μm and a thickness of 200 nm is formed so as to be orthogonal to the stripe-shaped opening of the p-type In _0.5 Ga _0.5 P conductive layer 6.

Next, as shown in FIG. 4E, p-type In _0.5 Ga is used with the striped SiO ₂ 11 as a mask.
_{The 0.5} P energization easy layer 6 is removed by etching.

[0078] Next, as shown in FIG. 4 (f), and a stripe-shaped SiO ₂ 11 as a mask, p-type an In _0.5 (Ga
_{The 0.3} Al _0.7 ) _0.5 P clad layer 5 is etched to form a ridge stripe. Here, for example, the ridge width is about 5 μm, the ridge thickness is 1.7 μm, and the ridge side face thickness is 0.25 μm.

Next, as shown in FIG.
An aAs (n = 2 × 10 ¹⁸ cm ⁻³ ) current blocking layer is selectively grown on the side surface of the ridge with a thickness of about 1 μm.

Next, as shown in FIG. 5B, the striped SiO ₂ 11 is removed by etching. That is, on the ridge stripe of the p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 3, the p-type In _0.5 Ga _0.5 P conducting layer 6 having the n-diffusion region 10 as an opening is exposed.

Thereafter, as shown in FIG. 5C, a p-type GaAs contact layer (p = 2 × 10 ¹⁸ cm ⁻³ ) 13 is formed to 3 μm, and AuZn / Au 14 is formed as a p-side electrode. AuGe / Au15 is formed as an n-side electrode to complete a semiconductor laser.

FIG. 5D is a partial cross-sectional perspective view of the semiconductor laser fabricated according to this embodiment. As shown in the figure, also in this embodiment, a semiconductor laser having the same structure as that of the first embodiment can be obtained. The end face non-injection type window structure semiconductor laser obtained by this embodiment also obtained substantially the same characteristics as those of the first embodiment.

Also in this embodiment, the active region 4
Although it was formed of the W active layer 20 and the light guide layers 16 and 19, of course, any semiconductor layer having a smaller band gap energy than the cladding layer may cause an increase in band gap energy due to Zn diffusion. Similar effects can be obtained.

In this embodiment, the oscillation wavelength is 680 nm.
m, but the oscillation wavelength can be varied by the structure of the MQW active layer 20. Here, in any wavelength band, the active layer portion is set to at least a PL wavelength of 20 n by Zn diffusion.
When the wavelength is equal to or more than m, the wavelength is shortened and functions as a window structure laser.

The embodiment of the invention has been described with reference to examples. However, the present invention is not limited to these specific examples.

For example, the impurities to be solid-phase diffused are not limited to Zn, but may be magnesium, beryllium,
Similarly, p-type impurities such as cadmium and mercury and n-type impurities such as silicon, tin, sulfur, selenium, and tellurium can be solid-phase diffused.

The formation of a p-type group III-V compound semiconductor layer serving as a diffusion source for solid-phase diffusion of a p-type impurity is as follows:
In addition to the metalorganic vapor phase epitaxy method described above, any of molecular beam epitaxy, hydride vapor phase epitaxy, chloride vapor phase epitaxy, or liquid layer epitaxy may be used, and the same effects as those described above can be obtained. Obtainable.

The present invention is similarly applied to various III-V compound semiconductor devices such as a light emitting diode, a photodiode, a field effect transistor, a bipolar transistor and the like in addition to the above-described semiconductor laser. Thus, a similar effect can be obtained. That is, according to the present invention, a solid phase diffusion of a dopant such as Zn can be performed with high controllability.

[0088]

According to the present invention, a dopant such as Zn can be introduced into a wafer with higher controllability than before in the manufacture of a III-V compound semiconductor device.
For example, Zn at a higher concentration can be diffused to a deep position in a wafer at a lower temperature and in a shorter time than before.

In particular, according to the present invention, when the active layer and the clad layer are mixed and crystallized by Zn diffusion to form a window structure in and near the light output end face of the semiconductor laser, a large amount of Zn is used as a Zn diffusion source. The III-V compound semiconductor layer containing a large amount of Zn is deposited on the surface of the wafer immediately above the region where the window structure is formed, and the Zn is diffused. . Conventional ZnO
When Zn is used as a diffusion source of Zn, the diffusion time of Zn is determined by the annealing time and the annealing temperature after ZnO deposition, but according to the present invention, Zn is further contained in a large amount. The thickness of the group IIIV compound semiconductor layer and the concentration of Zn are newly added as parameters.

In particular, with respect to the Zn content, Zn diffusion from the III-V compound semiconductor layer containing a large amount of Zn occurs remarkably, and Zn diffusion from other Zn-containing layers is suppressed. Therefore, the selectivity between the Zn diffusion region and the non-Zn diffusion region is increased as compared with the conventional example. As a result, according to the present invention, it becomes possible to produce various III-V compound semiconductor devices such as window structure semiconductor lasers with very high yield.

Further, according to the present invention, the window structure region has a structure in which current is not injected by the hetero-barrier by utilizing a large band gap difference between the cladding layer and the contact layer, thereby achieving high reliability. A window structure laser can be provided. That is, where a current is to be injected into the active layer, a layer having an intermediate band gap between the cladding layer and the contact layer, which is an easy conducting layer, is inserted between the cladding layer and the contact layer. A structure without a layer is adopted. This greatly simplifies the process and reduces the regrowth on the chip surface as compared with a current non-injection structure in which current is blocked by a conventional p-type / n-type / p-type transistor structure created by selective regrowth. As a result, it is possible to obtain an effect that no problem occurs when the semiconductor laser chip is mounted on the heat sink upside down.

[Brief description of the drawings]

FIG. 1 is a schematic process chart showing a method for manufacturing a semiconductor laser according to the present invention.

FIG. 2 is a schematic process chart showing a method for manufacturing a semiconductor laser according to the present invention.

FIG. 3 is a depth profile diagram of an ionized impurity concentration measured from a wafer surface by a CV method.

FIG. 4 is a schematic process chart showing a second semiconductor laser manufacturing method according to the present invention.

FIG. 5 is a schematic process chart showing a second method for manufacturing a semiconductor laser according to the present invention.

[Explanation of symbols]

Reference Signs List 1 n-type GaAs substrate 2 n-type GaAs buffer layer 3 n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 4 active region 5 p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 6 p-type In _0.5 Ga _0.5 P conduction easy layer 7 n-type GaAs cap layer 8 SiO ₂ mask 9 p-type GaAs layer containing Zn at a high concentration 10 Zn diffusion region 11 SiO ₂ mask 12 n-type GaAs current block layer 13 p-type GaAs contact layer 14 AuZn / Aup side electrode 15 AuGe / Aun side electrode 16 In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P first optical guide layer 17 InGaP well layer 18 In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P barrier layer 19 In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P Second optical guide layer 20 Multiple quantum well active layer

Claims (22)

[Claims] A first conductive type compound semiconductor substrate, a first conductive type clad layer, an active layer, a second conductive type clad layer, and a band gap smaller than the second conductive type clad layer. A contact layer of a second conductivity type having
A second conductive type conductive layer having a smaller band gap than the conductive type cladding layer and a larger band gap than the second conductive type contact layer, and emitting a laser beam from an end face. In the end face and the vicinity thereof, the cladding layer of the second conductivity type and the contact layer are laminated adjacently,
The current is suppressed by a hetero barrier at an interface between the second conductivity type clad layer and the contact layer. In a portion other than the vicinity of the end face, the second conductivity type clad layer and the contact are formed. A semiconductor laser device characterized in that energization is promoted by interposing the easy-to-conduct layer between the first and second layers. 2. The end face of the semiconductor laser device and the vicinity thereof are a window region formed of a compound semiconductor having a band gap larger than that of the active layer in other portions, and the window region is formed of the laser light. 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a band gap corresponding to an energy higher than the energy of the laser beam, so that the laser light is not absorbed in the window region. 3. The multiple quantum structure of the active layer, comprising a well layer having a smaller band gap than the clad layer and a barrier layer having a smaller band gap than the clad layer and a larger band gap than the well layer. 3. The semiconductor laser device according to claim 1, having a well structure. 4. The multiple quantum structure of the active layer has a multi-layer structure of a well layer having a smaller band gap than the clad layer and a barrier layer having a smaller band gap than the clad layer and a larger band gap than the well layer. The light guide layer having a well structure and a band gap larger than the effective band gap of the multiple quantum well structure and smaller than the cladding layer.
3. The semiconductor laser device according to any one of 2. 5. The method according to claim 1, wherein the second conductivity type cladding layer has a ridge stripe which is formed in a band-like manner along the direction in which the laser light is emitted. 5. The semiconductor laser device according to any one of 4. 6. The semiconductor laser device according to claim 5, wherein a current block layer of the first conductivity type is laminated on both sides of the ridge stripe of the cladding layer of the second conductivity type. 7. The compound semiconductor substrate is made of GaAs, and the first conductivity type cladding layer, the active layer, and the second conductivity type cladding layer are made of InGaAlP-based material. 7. The semiconductor laser device according to any one of 1 to 6. 8. A method of manufacturing a semiconductor laser device for emitting laser light from an end face, comprising: a first conductivity type cladding layer, an active layer, and a second conductivity type on a III-V compound semiconductor substrate. Forming a wafer in which a second conductive type conductive layer having a band gap smaller than that of the second conductive type clad layer is sequentially laminated, and the conductive layer is formed immediately above the end face and the vicinity thereof. The easy layer is selectively removed by etching,
Exposing a conductive type clad layer to the surface; and forming a second conductive type contact layer having a band gap smaller than that of the conductive layer on the exposed conductive layer and the conductive layer. Forming a semiconductor laser device. 9. A method of manufacturing a semiconductor laser device for emitting laser light from an end face, comprising: a first conductivity type cladding layer, an active layer, and a second conductivity type on a III-V compound semiconductor substrate. Forming a wafer in which a second conductive type conductive layer having a band gap smaller than that of the second conductive type clad layer is sequentially laminated, and forming a mask having an opening on the conductive layer. Forming Z on at least the wafer exposed at the opening.
n-type doped p-type III- doped with 2 × 10 ¹⁸ cm ⁻³ or more
Forming a group V compound semiconductor layer, and sequentially diffusing Zn from the p-type III-V compound semiconductor layer into the cladding layer of the second conductivity type, the active layer, and the cladding layer of the first conductivity type; Forming the end face by dividing the wafer so as to cross the portion of the mask where the opening is formed. A method of manufacturing a semiconductor laser device, comprising: 10. A method of manufacturing a semiconductor laser device for emitting laser light from an end face, comprising: a first conductivity type cladding layer, an active layer, and a second conductivity type on a III-V compound semiconductor substrate. Forming a wafer in which a cladding layer having a bandgap smaller than that of the second conductivity type and a second conduction type conduction layer having a smaller band gap than the second conduction type cladding layer; Forming on the mask; selectively etching and removing the conductive layer by etching the opening of the mask to expose the second conductivity type cladding layer; and at least the opening of the mask. The second exposed to
2 × 10 ¹⁸ cm ⁻³ of Zn on the surface of the conductive type cladding layer
Forming a doped p-type III-V compound semiconductor layer and forming the second layer from the p-type III-V compound semiconductor;
Sequentially diffusing Zn into the conductive type clad layer, the active layer, and the first conductive type clad layer; and dividing the wafer so as to cross the portion of the mask where the opening was formed. Forming the end face by using the method. A method for manufacturing a semiconductor laser device, comprising: 11. The step of diffusing is performed by performing an annealing treatment in an atmosphere containing hydrogen, nitrogen, or a group V element constituting the p-type III-V compound semiconductor layer. The method according to claim 9, further comprising a step of sequentially diffusing Zn from a —V compound semiconductor into the second conductivity type clad layer, the active layer, and the first conductivity type clad layer. A method for manufacturing a semiconductor laser device. 12. The semiconductor device according to claim 9, wherein said p-type group III-V compound semiconductor layer has a thickness of 0.2 μm or more.
12. The method for manufacturing a semiconductor laser device according to any one of the eleventh to eleventh aspects. 13. The p-type III-V compound semiconductor layer,
The method for manufacturing a semiconductor laser device according to claim 9, wherein the method is made of GaAs. 14. The method according to claim 9, wherein said mask is made of one of silicon oxide, silicon nitride, and aluminum oxide. 15. The method according to claim 9, wherein said mask is made of a compound semiconductor. 16. The method of manufacturing a semiconductor laser device according to claim 15, wherein said mask made of said compound semiconductor is doped with undoped or n-type impurities. 17. The semiconductor device according to claim 1, wherein the thickness of the mask is at least half the thickness of the cladding layer of the second conductivity type.
17. The method for manufacturing a semiconductor laser device according to item 5 or 16. 18. A method according to claim 15, wherein said mask is made of GaAs. 19. The p-type III-V compound semiconductor layer may be formed by any one of a metalorganic vapor phase epitaxy method, a molecular beam epitaxy method, a hydride vapor phase epitaxy method, a chloride vapor phase epitaxy method, and a liquid layer epitaxy method. 19. The method of manufacturing a semiconductor laser device according to claim 9, wherein the method is performed by: 20. A step of forming a mask having an opening on a wafer, and a p-type wherein Zn is doped at least 2 × 10 ¹⁸ cm ^-3 on a surface of the wafer exposed at the opening of the mask. Forming a group III-V compound semiconductor layer, and diffusing Zn from the p-type group III-V compound semiconductor into the wafer. Production method. 21. The method according to claim 20, wherein said step of diffusing includes a step of diffusing said Zn by performing an annealing treatment. 22. The method according to claim 21, wherein the annealing is performed in an atmosphere containing hydrogen, nitrogen, or a group V element constituting the p-type III-V compound semiconductor layer. A method for manufacturing a III-V compound semiconductor device.