JPH0258287A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a device whose reactive current component which does not contribute to laser oscillation is small by a method wherein, from a GaAs buffer layer of second conductivity type to a second clad layer, an active layer and a half of the thickness of a first clad layer just under the buffer layer, second conductivity type dopant is diffused until the above layers are inverted to the second conductivity type. CONSTITUTION:The title device is constituted of the following: a first clad layer 2 of AlGaAs, an active layer 3 of AlGaAs, and a second clad layer 4 of AlGaAs which are laminated on a first conductivity type substrate 1 of GaAs; a buffer layer 5 of GaAs, a first current blocking layer 6 of AlGaAs, a second current blocking layer 7 of GaAs, a third current blocking layer 8 of AlGaAs, and a fourth current blocking layer 9 of GaAs which are laminated on the part except a stripe trench 12; a third clad layer 10 of AlGaAs and a contact layer 11 of GaAs which are laminated so as to fill the stripe trench 12. A region 13 is formed by diffusing second conductivity type dopant into the second clad layer 4, the active layer 3 and a half of the thickness of the first clad layer 2 just under the buffer layer 5, until the layers are inverted to the second conductivity type.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device used as a light source for CDs and VDs.

[Conventional technology]

FIG. 3 is a sectional view showing an example of a conventional semiconductor laser device. In this figure, 1 is a GaAs substrate having an n-type (denoted as n-) conductivity type, 2 is an n-AlGaAs Lth cladding layer provided on this substrate 1, and 3 is this first cladding layer. 2 is an AjGaAs active layer having an n-type, p-type, or intrinsic conductivity type, and 4 is a p-AI GaAs active layer provided on this active layer 3.
A second cladding layer 5, a GaAs buffer layer having p-type conductivity provided on a region other than the stripe groove portion on the second cladding layer 4; 6, 7, 8.9 the The first to fourth current blocking layers provided on the buffer layer 5, the third cladding layer 11 of AlGaAs having p-type conductivity and provided to bury the stripe groove portion, and the third current blocking layer 11. A GaAs contact layer 12 having p-type conductivity provided on the cladding layer 10 is
Live groove.

Next, the operation will be explained.

The current 14 injected from the contact layer 11 having a p-type conductivity reaches the substrate 1 having an n-type conductivity.

During this process, the current 14 injected into the region of the active layer 3 excites electrons in the active layer 3, causing laser oscillation. A laser beam is then emitted in a direction perpendicular to the cross-sectional view of FIG.

[Problem M that the invention seeks to solve]

Since the conventional semiconductor laser device is configured as described above, when the current 14 that is directed flows from the third cladding layer 10 to the second cladding layer 4, it spreads in the 1ζ lateral direction, causing There was a problem that the current density became small.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a semiconductor laser device that can increase the density of current flowing through the active layer.

[Means to solve the problem]

In the semiconductor laser device according to the present invention, a dopant of the second conductivity type is applied from the GaAs buffer layer having the second conductivity type to the middle of the thickness of the second cladding layer, the active layer, and the first cladding layer immediately below the second conductivity type. It is diffused until the conductivity type is reversed.

[Effect]

In this invention, since the dopant of the second conductivity type is diffused from the GaAs buffer layer into the middle of the thickness of the first cladding layer until the dopant is inverted to the second conductivity type, a forward bias in areas other than the stripe groove portion is achieved. The diffusion potential of the pn junction becomes higher than that of the s1-live portion, and the current does not flow laterally but only directly under the s1-live portion.

[Example 1 An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, numerals 1 to 11 are the same as those in FIG. Direct p-AIGaAS second cladding layer4. AlGaAs active layer 3. and n −A I
A p-type dopant, for example, Zn, is diffused halfway through the thickness of the GaAs first cladding layer 2 until p-inversion occurs. 13 is the p-type dopant) region.

Next, we will discuss the manufacturing method of the semiconductor laser device shown in FIG.
This will be explained with reference to the figures.

First, as shown in FIG. 2(a), n-type GaAs is deposited on the substrate 1 in the first crystal growth, and n-type A e w (
y a I-x As first cladding layer 2. p-type or n-type or intrinsic AlyGap-yAs activity la
3 p p-type At', Ga, -, As second clad layer 4.1) type GnAs buffer N 5 p n-type A
12Gr11-z A S first current blocking layer5. n-type G
a A s second current blocking layer 7 + n-type AN, Gap-
zAs third current blocking layer 8. Then, epitaxially grow an n-type GaAs fourth current blocking IF layer 9.

Next, as shown in FIG. 2(b), a fourth current blocking layer 9. Third current blocking layer8. Then, the second current blocking layer 7 is etched away in stripes to form striped grooves 12.

Next, as shown in FIG. 2(C), unsaturated or saturated GaAs or G
a -A l -A Strive groove 1 by s-based melt
The p-type GaAs buffer layer 5 present at the bottom of the substrate 2 is removed by meltback.

Subsequently, in the second crystal growth, as shown in FIG. 2(d), in the same apparatus, p-type At-G was grown to fill the stripe grooves 12 using the liquid phase epitaxy cell growth method.
a1-zAs third cladding layer 10 and p-type GaAs contact!・While layer 11 is sequentially grown as an epitaxial cell, p-type GaA existing in the region other than the stripe groove portion is grown.
p-type A j Ga A directly below sba sofa layer 5
s activity J13. and n-type Alx (za, -As). A p-type dopant is diffused into the middle of the first cladding layer 2 by autodobin until the conductivity type is reversed to ρ, thereby forming a p-type dopant region 13.

Next, the operation of the semiconductor laser device according to the present invention will be explained.

The current 14 injected from the contact layer 11 having a p-type conductivity reaches the n-GaAs substrate 1 having an n-type conductivity. On the way, the current 14 flowing through the AjGaAs active layer 3 is caused by the diffusion potential of the pn junction which is forward biased under the p-type dopant region 13 formed in the area other than the stripe groove 12PA.
Since it is higher than that of the stripe groove, it should flow only directly below the stripe groove 12 portion.

Note that the above embodiments can be similarly applied even when the n-type and p-type are replaced.

[Effect of the invention] As explained above, the invention of Party B has a G
Dovan! of the second conductivity type extends from the aAs buffer layer to the middle of the thickness of the second cladding layer immediately below, the active layer, and the first cladding layer.・Diffused until it is reversed to the second conductivity type, the current flows only straight through the stripe grooves. Therefore, the current density in the active layer can be increased, and the threshold voltage and operation can be increased. I wonder if it will be effective to reduce the current.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a semiconductor laser device according to an embodiment of the present invention, FIG. 2 is a process cross-sectional view for explaining a method of manufacturing the semiconductor laser device of the present invention, and FIG. 3 is a cross-sectional view of a conventional semiconductor laser device. FIG. 2 is a cross-sectional view showing a laser device. In the figure, 1 is an n-GaAs substrate, 2 is an n-GaAs substrate, and 2 is an n-GaAs substrate.
AlGaAs first cladding layer, 3 is AIGaks active 1
-14 is p-AjGaAs second cladding layer, 5 is p-G
a A sba/sofa layer, 6 is n -A I G a
7 is an n-Ga As second current blocking IE layer; 8 is an n-A I Ga As third Ti current blocking layer;
a current blocking layer; 9 is an n-GaAs fourth current blocking layer;
10 is p-AlGaAs third cladding layer, 11 is p-G
nAs=+cut layer, 12 is striped groove, 13 is p
W4 dopant region, 14 is a current. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 1 Agent: Masuo Oiwa (and 2 others) Figure 3 Figure 1, Indication of the case Patent Application No. 1983-208971 2, Name of the invention Semiconductor L. The device and its manufacturing method 3, Amended The number of inventions increases due to the amendment by the representative of the applicant (6), the current density can be increased in the title of the invention column, claims column, and detailed description of the invention column of the positive subject specification. The correction says, ``Reactive current components that do not contribute to laser oscillation can be reduced.'' (2) The scope of claims in the specification shall be amended as shown in the attached sheet. (3) "Semiconductor laser device" on page 2, line 18 of the specification is corrected to "semiconductor laser device and its manufacturing method." (4) Similarly, on page 4, lines 9-10, "There was a problem that the current density in the active layer 3 became small" was replaced with "There was a problem that there was a large reactive current component that did not contribute to laser oscillation." ”, he corrected. (5) Similarly, on page 4, lines 12-13, "the density of the current flowing through the active layer can be increased" is corrected to "the reactive current component that does not contribute to laser oscillation is small." (6) Also on page 8, lines 12-13, [2 in the active layer, Claims ■ kl・At' which has a first conductivity type, a second conductivity type, or an intrinsic conductivity type, and is provided on the A I
vGa1-, As active layer and this Al, Ga1-y A
A Z having the second conductivity type provided on the S active layer
XG a I-KA s second cladding layer and this AI. Ga, ..., GaAs having a second conductivity type provided on a region other than the stripe groove portion on the second cladding layer
a buffer layer, and a first conductivity type provided on the GaAs buffer layer, A l zG a with 2≧0.4;
, -2A s first current blocking layer and this AI. a GaAs second current blocking layer having a first conductivity type provided on the Gap-2As first current blocking layer; and a GaAs second current blocking layer having the first conductivity type provided on the second current blocking layer, and Z≧0. A1 which is 4. Ga1-zAs third current blocking layer and this klz
A GaAs fourth current blocking layer having a first conductivity type provided on the Ga□-A third current blocking layer, and an At' layer having a second conductivity type provided so as to fill the stripe groove portion. Ga, -0As third cladding layer and this At'
, Ga1-, the A contact layer having the second conductivity type provided on the third cladding layer, and directly under the GaAs buffer layer having the second conductivity type.
I, Ga 1-, As second cladding layer, Al
yG a 1-YAs active layer and the A I , G
a,, As, a first conductivity type region in which a second conductivity type dopant is diffused to the middle of the thickness of the first cladding layer until it is inverted to the second conductivity type. A laser μ-shape unit that is intended to form a skewer-shaped layer and a first skewer-shaped A

Claims (1)

[Claims] an Al_xGa_1_-_xAs first cladding layer having a first conductivity type provided on a GaAs substrate having a first conductivity type; and a first conductivity type or second conductivity type provided on the Al_xGa_1_-_xAs first cladding layer. Or Al_yGa_ which has an intrinsic conductivity type and where x>y
1_-_yAs active layer and this Al_yGa_1_-_
Al_ with the second conductivity type provided on the yAs active layer
xGa_1_-_xAs second cladding layer and this Al_
xGa_1_-_xAsG having the second conductivity type provided on the region other than the stripe groove portion on the second cladding layer
Al_zG having an aAs buffer layer and a first conductivity type provided on the GaAs buffer layer and having z≧0.4.
a_1_-_zAs first current blocking layer and this Al_zG
a_1_-_zAs first current blocking layer provided on the first current blocking layer
a GaAs second current blocking layer having a conductivity type and a first conductivity type provided on the second current blocking layer, z≧0.4;
a third current blocking layer of Al_zGa_1_-_zAs, a fourth current blocking layer of GaAs having the first conductivity type provided on the third current blocking layer of Al_zGa_1_-_zAs; an Al_xGa_1_-_xAs third cladding layer having a second conductivity type; and a GaA having a second conductivity type provided on the Al_xGa_1_-_xAs third cladding layer.
The Al_xGa_1_-_ immediately below the GaAs buffer layer having the second conductivity type and composed of the s-contact layer.
xAs second cladding layer, Al_yGa_1_-_yAs
A second conductivity type dopant is added to the middle of the thickness of the active layer and the Al_xGa_1_-_xAs first cladding layer.
A semiconductor laser device comprising a first conductivity type region which is diffused until the conductivity type is reversed.