JPS61171185A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To stabilize the characteristics by method wherein an impurity introduced region is made to function as the current block layer by selectively introducing an N-type impurity to a P-type semiconductor substrate, and then a double-hetero structure is formed on the substrate and the impurity introduced region. CONSTITUTION:After a stripe mask is formed on the P<+> GaAs substrate 11, Si<+> is implanted. Thereafter, the mask on the substrate is removed, and the wafer is subjected to capless annealing in a thermal decomposition furnace of organic metal, thus forming an N-GaAs layer 12. At this time, a stripe section 13 is formed immediately under the mask. Then, organometallic compounds are introduced to successive growth of a P-Ga0.55Al0.45As clad layer 14, an undoped Ga0.86Al0.14As active layer 15, an N-Ga0.55Al0.45As clad layer 16, and an N<+> GaAs layer 17. An N-electrode 18 and a P-electrode 19 are formed to this epitaxial wafer. This process enables the flat formation of epitaxial grown layer because of the formation of a current structure layer in the flat substrate and the enlargement in selecting width of the growing method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for forming a current confinement layer in a semiconductor laser having an internal stripe structure, and more particularly to a semiconductor laser for consumer use and information terminals.

[Background of the invention]

The conventional semiconductor laser device is disclosed in Japanese Patent Application Laid-Open No. 57-211290.
As described in the issue, striped grooves (V grooves or trapezoidal grooves) are formed on the wafer to limit the current passage area, so the current confinement width depends on the processing accuracy of the stripe width of the groove etch mask material, There was instability in the laser device characteristics, such as variations in values depending on the thickness accuracy of the current confinement n-GaAS layer.

In addition, only liquid phase growth can be applied to flatten the grooves formed by processing, and the selection range of crystal growth methods is narrow.

[Purpose of the invention]

An object of the present invention is to provide a structure that is effective as a method for forming a current confinement layer that embodies an internal stripe structure, and to provide an inexpensive visible semiconductor laser for consumer use or information terminals that can be mass-produced. .

[Summary of the invention]

Conventional semiconductor lasers with four internal stripes have some form of V-groove or trapezoidal groove in the substrate or epitaxial layer, and the laser fabrication method involves burying this. Particularly in organic metal pyrolysis, it is difficult to change the substrate shape. Since storage and growth occur, various problems have arisen. In the present invention, for example, the current passing region or laser stripe is formed directly on the substrate by ion implantation, and since the substrate surface shape is flat without any particular change, the next step, double heterojunction formation, is extremely difficult. It has the advantage of being easy to use. In particular, the organometallic thermal decomposition method has a very advantageous aspect in terms of the manufacturing process in that the annealing process after ion implantation can be performed simultaneously with crystal growth. Note that it is preferable to use an ion implantation method to introduce an n-type impurity into a p-type substrate, and to use an ion implantation or diffusion method to introduce a p-type impurity into a p-type substrate or an n-type substrate.

Hereinafter, the present invention will be explained in detail using Examples.

[Embodiments of the invention]

Example 1 A semiconductor laser in which a current confinement layer was formed by ion-implanting n-type impurities into a p0-type QaAs substrate.

In FIG. 1, after forming a striped mask with a width of 2 μm on a p''-GaAa substrate 11, the dose amount is 2×10” at an acceleration appropriate pressure of 200 kV in an ion implantation device.
tMI-Insert snow Si0. After this, the mask on the substrate is removed and the wafer is placed in an organometallic pyrolysis furnace for approximately 800
Capless annealing is performed in an arsenic atmosphere for about 2 hours at zero temperature to form an n-QaAs' layer 12. At this time, a stripe portion 13 is formed directly below the mask. Subsequently, organometallated metals were introduced, 9 Gao, ss At
6.41A 1 has a cladding layer 14 (thickness 1.5 μms
I)~I
, 4sAI cladding layer 16 (thickness L5 pm, n
-1x I Qll,, -3), n"-GaAs cap layer 17 (thickness Q, 5 μm, n-1x 10"tM-"
) grows in the order of After forming an n-electrode 18 and a p-electrode 19 on this epitaxial wafer, a laser element with a cavity length of 300 μm was fabricated by a cleavage method.

The fabricated device continuously oscillates at room temperature with a threshold current of 30 to 50 mA at an oscillation wavelength of 7 gQ nm, and an optical output of 10 mA.
It oscillated in a stable transverse fundamental mode up to W.

Example 2) A semiconductor laser in which p-GaAs is grown in one step on a p''-GaAs substrate, and then n-type ions are implanted to form a current confinement layer.

In FIG. 2, the p''-GaAl! substrate 21 is first
GaAs layer (thickness 0.5 A ffh I' ~ I
After forming the IO""crn-") 22, 3t+ ions are implanted and annealing is performed in the same manner as described in Example P to form the n-type current blocking layer 23. Next, metal organic pyrolysis is performed. A p-cladding layer 24, an undoped active layer 25, an n-cladding layer 26, and an n-cap layer 27 are successively crystal-grown by a method.After forming an n-electrode 2B and a p-electrode 29 on this epitaxial wafer, it is then cleaved. When a laser device with a cavity length of 300 μm was manufactured by the method, the same effect as in Example P was obtained.

Example 3) A semiconductor laser in which an n-type GaAs layer was formed on the entire surface of a wafer, and then Zn ions were implanted into the S1 drive portion to form a current confinement layer.

In FIG. 3, n1lQ a is applied to the p''-QaAs substrate 31
A 8 layers 32 (thickness 0.7μm, n=3X 10”
cIn') was formed by an organometallic thermal decomposition method, and then the mi flow passing region 33 was formed in a stripe shape by a Zn0 ion implantation method using a mask. After removing the mask,
A semiconductor laser was formed by the same steps as in the above example.

As a result, almost the same results as in the above example were obtained.

Embodiment 4) A semiconductor laser in which the p-type current passing region has different widths in the stripe direction in the above embodiment.

FIG. 4 shows a plan view of the semiconductor laser device of Examples p to 3) in the middle of the manufacturing process, and 43 indicates the surface of the substrate. The p-type current passing region, or stripe, is designed to be narrow near both end faces 41 of the laser, as shown in the figure, and wide near the center 42. The region 43 other than the stripe is a current confinement layer. In the next step, a double heterojunction was formed in the same manner as in the above example, and a semiconductor laser device was manufactured. As a result, it oscillated in a stable transverse fundamental mode up to an optical output of 10 mW. The wavelength was 780 nm, and by changing the excitation region in the stripe direction, mode conversion occurred, and as a result, the astigmatism of the laser beam was reduced to about 5 μm or less. Moreover, the oscillation spectrum was multimode.

In the above embodiments, the semiconductor materials are GaAl/G, aA, /,
A8 type, but InP/InGaASP type or I
Even if other materials such as nGaP/InGaAtP are used, the same implementation as in the above embodiment is possible.

〔Effect of the invention〕

According to the present invention, in order to form a current confinement layer in a flat substrate, the subsequent epitaxial growth layer can also be formed flatly. This has the effect of widening the range of legal options. In addition, since the ion implantation method is used as a method for forming the current confinement layer, the uniformity of the stripe width within the wafer is good, it is easy to form a large area ratio, and it is highly effective as a laser manufacturing method with a high yield.

[Brief explanation of drawings]

1 to 3 are cross-sectional structural diagrams of a laser to illustrate one embodiment of the present invention, and FIG. 4 is a plan view of a laser to explain another embodiment of the present invention.

Claims (1)

[Claims] 1. N-type impurities are selectively introduced into a p-type semiconductor substrate from the outside, the already impurity-introduced region is made to function as a current blocking layer, and then a double layer is formed on the existing substrate and the impurity-introduced region. A semiconductor laser device characterized by forming a heterostructure. 2. A p-type conductive layer on a p-type semiconductor substrate with a carrier concentration of 1×
10^1^7cm^-^3~1x10^1^8cm^-
It is grown by vapor phase epitaxy or molecular beam epitaxy within the range of ^3, and then an n-type impurity is selectively introduced from the outside to make the existing region function as a current blocking layer, and then the existing substrate and the impurity introduced region are grown. A semiconductor laser device characterized by having a double heterostructure formed thereon. 3. Introduce an impurity onto a p-type semiconductor substrate to form an n-type conductive layer, and then selectively introduce the same p-type impurity as the substrate in a stripe pattern, and then form a double heterostructure on the existing substrate. A semiconductor laser device characterized in that: