JPS61236184A - Preparation of semiconductor laser element - Google Patents

Abstract

PURPOSE:To simplify the production process, make the contact of electrodes easy, and reduce the leak current, by forming a current constriction layer and a refraction index wave guide layer in the inside by Si implantation with high energy. CONSTITUTION:On the (001) face of the N-type GaAs substrate 1b, the following layers are laminated; the N-type GaAs buffer layer 2b, the N-type AlxGa1-xAs/ GaAsMQW buffer layer 3b, the N-type AlzGa1-zAs/AlwGa1-wAsMQW active layer 6, the P-type AlyGa1-yAs photo guide layer 7b, the P-type AlxGa1-xAs clad layer 8b and the cap layer 14. On the surface of this element, the metal mask is formed leaving the stripe in the (110) direction, and the Si ion with high energy is implanted to form the current constriction region 10. The P-type GaAs contact layer 9b is grown by epitaxy, when the MQW structure of the active layer 6 gives way to become the uniform mixed crystal, and the portion of low refraction index is formed in the oscillation region. Then, the P-side electrode layer 13 and the N-side electrode layer 12 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a multiple quantum well (MQW') index-guided semiconductor laser device using GaAlAs-based materials.

(Prior Art) Conventionally, MQW index-guided semiconductor laser devices have been manufactured by one-time epitaxial growth and zinc diffusion. This manufacturing example will be explained based on FIG. 2. By epitaxial growth, p
Type GaAs buffer layer Yu α, p type A1. Ga 1-, A
ll /G (BAJMQW buffer layer 3α, p-type Als
Ga1-gAs cladding layer 11a, p-type AlyGα1-
yAs optical waveguide layer α, A jf G31-fAJ/Aj
#Gα, -wAaMQW active layer 6.3 type AjyGa1-
yAs optical waveguide layer 7cL, n-type klzGa 1-zA
After laminating the s cladding layer gα and the n-type GaAs contact layer 9α, a stain flow constriction region 10 is formed in the shaded area by Zn diffusion.
At the same time, a refractive index waveguide mechanism is formed by destroying the MQW of the active cell, and then an n-type AjgGe1-π
After forming an insulating film // on the A8 cladding layer α, an n-side electrode layer 2 is deposited thereon, and a p-side electrode layer 13 is deposited on the back surface of the p-type A8 substrate/a.

(Problems to be Solved by the Invention) However, in the manufacturing method of the semiconductor laser device as described above, it is difficult to eliminate the internal stripe structure, which complicates the manufacturing process, and the zinc diffusion used in this device also complicates the manufacturing process. 7. It takes too much time for diffusion and it is difficult to control the carrier concentration. In some trout, the carrier concentration in one rad layer jα can reach as high as 103-s. Therefore, the resistance of the current confinement layer 10 is small, and a large leakage current occurs when the output is high.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, Si ions are implanted with high energy to form a current confinement layer and a refractive index waveguide layer inside the klGaAs system. This paper proposes a method for manufacturing an MQW index-guided semiconductor laser device using this material.

Here, the Si ions are annealed at a low temperature (700°C), such as during epitaxial growth, and the MQW structure of the MQW active layer into which the S Type in. Specifically, the energy is 1 to 3 M-■, and the dose is set so that the Si ion concentration in the MQW active layer is about 1.times.10.sup.9ffi.sup.-1.

- (Effect of invention) becomes.

In addition, in this invention, since the S (ion implantation method) is used, the carrier concentration can be easily controlled. Therefore, the carrier concentration in the ion implanted portion of the cladding layer can be kept as low as possible, and the cladding layer If the composition of Aj is 0.5 or more, a deep unit is formed for Si ions, so the resistance of the current confinement portion is greater than that obtained by conventional zinc diffusion, and leakage current is reduced.

Furthermore, since the present invention uses the SS ion implantation method, the stripe width can be easily controlled.・Therefore, it is possible to perform transverse fundamental mode oscillation up to high output with a low oscillation threshold current. Further, since the semiconductor laser device obtained according to the present invention has small astigmatism, it is suitable as a light source for digital audio disks, optical disk memories for writing and reading, laser beam printers, and the like.

In this case, the MQW structure of the MQW active layer into which 1M ions have been implanted collapses at a low temperature of about 700°C, and as described above, when Si ions are implanted into the MQW active layer at high energy, Damage inside the element will be recovered in about 20 minutes at 700°C. That is, since it is recovered before the second epitaxial growth, there is no adverse effect caused by damage during Si ion implantation.

(Example) The present invention will be explained below based on the illustrated example. 1st
The figure shows an example of the manufacturing process of an Aj GaAs MQW index-guided semiconductor laser device according to the present invention. )
The (001
) on the n-type Gaps buffer layer 2b, n-type AjgG
41-gAj/GaAa MQW buffer layer, 76
%s M Al&Gα1-gha cladding layer <xb,
n-type Aj.

Ga1-, As optical waveguide layer! rb, AlgGcLl-g
A8/A1wGG1-@haMQW active layer 6, p made AJ
, Ga1-, Aa optical waveguide layer qb, p-type AlsGcL1
-gAJ1 cladding layer tb, cap layer 14! Laminate.

Note that the composition of Al varies depending on the application, but 2>y>g
> u, and Z > 0.3.

The MQW buffer layer 3b may be omitted in the case of OMVPE growth.

The cap layer /l is provided to prevent the surface of the cladding layer tb from being exposed to the atmosphere during the next epitaxial growth process, and may be composed of a thin film of -As, but in this example, it is grown at a low temperature. A substance that forms a thin film at normal epitaxial growth temperatures and evaporates at normal epitaxial growth temperatures. A thin film with a thickness of about 1ooX is formed using an In compound such as LP, InAa, Inch, etc.

In addition, the MQW active layer wall and thickness are such that the MQW structure collapses due to Si ion implantation and annealing, and when it becomes a uniform mixed crystal, the refractive index at the oscillation wavelength is smaller than the refractive index of the MQW structure, and the oscillation Set so that the threshold current is low.

A metal mask is applied to the surface of the elements stacked as described above, leaving stripes with a width of 5 μ in the (110) or (rTO) direction, and high-energy Si ions are implanted. Note that the thickness of the metal is such that SS ions do not reach the cap layer 13.

In addition, S (ions) are implanted at a concentration (approximately 5×1♂"m-") such that the MQW active layer's original QW structure will be annealed and collapsed during the next epitaxial growth, and in this example, the implantation energy is are set to 2M and V, and SS ions are implanted in the shaded area to form a current confinement region io.

Next, the normal epitaxial growth temperature (70°C) is applied in the growth chamber.
0t: approx.) and apply M pressure while forming the cap layer l.
After evaporating the film, the shift layer tb is formed by the 22nd epitaxial growth using the MBE growth method or the OMYPE method.
A p-type Gaps contact layer 9b is laminated thereon.

Conversely, a contact layer 9b is laminated on the cladding layer gb,
Contact layer 9b may be further grown in the second epitaxial growth. In this case, the cap layer/3 may not be provided.

Note that the thickness of the contact layer 9b and the second layer tb1 are also related to the implantation energy of SS ions, so which of the above to be adopted is determined in consideration of these factors.

On the other hand, in the MQW active layer 6 implanted with Si ions, its MQW structure collapses during the second epitaxial growth process and becomes a uniform mixed crystal, forming a portion with a low refractive index at the oscillation wavelength.

Also, S<the damage caused by ion implantation is 700℃,
The recovery was confirmed by annealing under M pressure for 20 minutes, as confirmed by the Si activation rate after implantation. This does not have any influence on the second growth because the damage is recovered while the layer to be recovered under the A8 pressure before the growth is evaporated at 700°C.

Furthermore, a p-side electrode layer 13 and an n-side electrode layer /J are formed by vapor deposition on the contact layer 9b and the back surface of the n-type GaAs substrate 1b, thereby manufacturing a semiconductor laser device.

Next, to describe the operating principle of the semiconductor laser device obtained in this manner, by grounding the p-side electrode layer 13 and applying a negative voltage to the outer electrode layer l-, the stain flow can be suppressed from the cladding layer tb.
, is constricted by the current confinement region 10 of the optical waveguide layer 7b, and is injected into the MQW structure portion of the MQW active layer to emit light.

This light is guided by the upper, lower, left and right parts with low refractive index, and oscillates.

Furthermore, by controlling the stripe width by implanting Si ions, it is possible to ensure a low oscillation threshold current, high efficiency operation, and a lateral fundamental mode up to high output.

In this example, the surface of the cladding layer gb is covered with the cap layer /3 until the second epitaxial growth and is not exposed to the atmosphere, so the surface of the cladding layer gb is not exposed to the atmosphere.
A high resistance portion is not formed between the contact layer 9b and the contact layer 9b, and a thin film made of an In compound that evaporates during the second epitaxial growth process is used as the cap layer 13. The steepness of the j5 MQW structure is not impaired by heat for removing the cap layer 13.

[Brief explanation of drawings]

Figure 1 shows an example of the manufacturing process of the present invention. Figure 1 (α) shows the first epitaxial, growth and Ss ion implantation process, and Figure 1 (6) shows the second process. FIG. 2 is a perspective view of a semiconductor laser device manufactured by a conventional method. In the figure, 6 is an MQW active layer, and 10 is a current confinement region.

Claims (2)

[Claims] (1) A method for manufacturing an AlGaAs multiple quantum well refractive index waveguide semiconductor laser, characterized in that Si ions are implanted at high energy to form a current confinement and refractive index waveguide region inside. (2) Set the energy and dose of Si ion implantation to S
2. The manufacturing method according to claim 1, wherein the multi-quantum well structure of the multi-quantum well active layer into which i-ions have been implanted is set so as to be annealed and destroyed during subsequent epitaxial growth.