JPS6076183A - Visible light semiconductor laser element and manufacture thereof - Google Patents

Abstract

PURPOSE:To establish long-life operating characteristics by constituting an active layer or a light guide layer formed on a GaAlAs layer with particular crystals of five elements mixed crystal and producing the laser element with the superior quality crystals of InGaAlAsP. CONSTITUTION:When an active layer is caused to epitaxially grow on a GaAlAs clad layer, crystals of five mixed elements consisting of In, Ga, Al, As and P are used for the active layer. On a (100) P-GaAs substrate 1, an N-GaAs current entrapping layer 2 is caused to grow and thereafter stripe grooves are formed by chemical etching with use of photo-lithography. These stripe grooves serve as current paths from which the current entrapping layer 2 has been removed. Then, a P-Ga0.2Al0.8As clad layer 3, non-doped In0.28(Ga0.62Al0.38)0.72As0.45 P0.55 active layer 4, an N-Ga0.2Al0.8As clad layer 5 and an N-GaAs cap layer 6 are caused to grow subsequently by the liquid phase epitaxial growth. Au-Ge-Ni and Au-Zn are then vapor deposited as an N-side electrode 7 and a P-side electrode 8, respectively, and heated to form the same. In such a manner, a semiconductor laser element of double heterojunction type is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a semiconductor laser device, and more particularly to a new and useful visible light semiconductor laser device having an oscillation wavelength of 730 nm or less and a method for manufacturing the same.

<Prior Art> With the development of optical information processing equipment such as optical disk devices and laser beam printers that use semiconductor laser devices as signal light sources, there has been a demand for shorter oscillation wavelengths for visible light semiconductor laser devices. It has become. In response to this demand, remarkable progress has been made in GaAlAs semiconductor laser devices, and in particular, 780 nm band devices have an estimated 106 nm at room temperature.
It has a long lifespan of more than an hour and has become widely used as a light source for compact discs. However, the oscillation wavelength of GaAlAs semiconductor laser devices is 78
When the wavelength becomes shorter than 0 nm, the operating life tends to be rapidly shortened, and it is currently difficult to ensure a practical operating life particularly in the short wavelength region of 7 aonm or less. Regarding this, please refer to T., Kajim.
ura Journal of Applied P
hysics.

Vol. 51, P2O3 (1980). on the other hand,
A quaternary mixed crystal of InGaAsP lattice-matched to GaA3 is used as a crystal for the active layer to obtain oscillation in a short wavelength range. When the active layer is composed of this quaternary mixed crystal, and the cladding layer is made of a quaternary mixed crystal composed of the same elements, the maximum energy gap is Ino, 49 Ga0.5
j Since it is limited by 1.9 eV of P, the energy gap difference between the cladding layer and the active layer is set to 0.25 eV.
When set to , the oscillation wavelength can only be shortened to about 750 nm. When GaAlAs is used for the cladding layer, high-quality crystals can be obtained by liquid phase growth up to an A1 mixed crystal ratio of 0.8. Ga0,2 Al (3B A
Since the energy gap of s is 2.09eV, 6
It is expected that the wavelength can be shortened to about 70 nm without significant characteristic deterioration such as deterioration of temperature characteristics.

However, when actually confirmed through experiments, GaA
When InGaAsP quaternary mixed crystal is grown on lAs by liquid phase growth, the growth is often not uniform over the entire surface.
This was particularly inconvenient for growing a thin active layer. The reason for this is that the surface of the growth layer is contaminated by P (references:
A, 5uzuki, T, Murakami.

y, Kur jayama and H, Mat s.
unami + Japanese Journal
oj, Applied Physics, vol. 2
+, P, 236B) and As mixed crystal ratio is increased.
, Journal of Applied I'1
1ysics, vol.

54, P, 2635).

<Object of the Invention> In view of the above-mentioned problems, the present invention has been made to provide a novel and useful device in which the active layer of a short-wavelength visible light semiconductor laser device can be made of a high-quality crystal made of InGaAIAsP, and long-life operating characteristics have been established. The purpose of the present invention is to provide a semiconductor laser device. Another object of the present invention is that InGaAIAs
The object of the present invention is to establish a simpler manufacturing process by omitting the step of diluting At when manufacturing a semiconductor laser device having a quinary active layer made of P.

<Description of structure and effects> The present inventor has found that when growing InGaAsP on an underlying layer of GaAs, GaAlAs, etc., a uniform growth layer can be obtained by adding a small amount of Al to the growth solution. I found it. For example, with In solvent, I O-'
Add diluted AI to one mole unit and grow at a growth temperature of 7.
When liquid phase growth was performed on a (+00) GaA3 substrate at 85° C., it was found that an InGaAIAsP layer was epitaxially grown with good reproducibility. It has also become clear that the Al mixed crystal ratio is uniquely determined by controlling the As mixed crystal ratio at this time. That is, as a result of measurement by EPM A, (Al zca I-z )xT n 1-
) (z=o in AsyP +-y, 66y2+ 5
．． A crystal with an At mixed crystal ratio of 48y is obtained. Therefore, when epitaxially growing an active layer on a GaAlAs cladding layer, it is more advantageous to use an InGaA1'AsP 5-element mixed crystal as the active layer than to use an InGaAsP 5-element mixed crystal as the active layer. When manufacturing a semiconductor laser device as a semiconductor laser device, the distribution coefficient of Al into the solid phase is 1
04 or more, which makes the process of diluting AI with an In solvent complicated, but as mentioned above (without strictly determining the amount of Al added, by controlling the As mixed crystal ratio, it is possible to mix Al). Since the crystal ratio can be controlled and set arbitrarily, the solution in which the GaAlAs cladding layer was grown can be left slightly on the substrate when the substrate is slid for the next growth of the In GaAIAsP active 8 layer. , I
By determining the size of the so-called gap, which is the distance from the substrate surface to the carbon boat when the substrate slides during multilayer growth, so that it is mixed in the GaAlAs cladding layer growth solution. A1 can be used to grow a 1nGaAIA'sP active layer. Therefore, the step of diluting Al is omitted.

Actually, InGaAIAsP/Ga082Al(1,BA
A single heterostructure of s was grown on a (100) GaAs substrate.

First, in order to grow As-free I nGa A I P, a solution consisting of In, Ga, and P was used to grow the second layer on Gao, z AIo, 8 As.
n 0.49 Ga 0.5I 1 only by the growth of P
No growth of nGaAIP$ or InGaAIAsP occurred. This is explained in Reference: M.

Kazumura, I, Ohta and I,
Teramoto, Japanese Journal
of Applied Physics, vo
I, 22, P, 654 (1983). Therefore, it can be seen that liquid phase growth of InGaAIP that does not contain As is difficult. Also, Ink, 49
61.51 If F is the active layer, then Q, a A I A
S is not suitable as a cladding layer because it has a small energy gap, leading to an increase in threshold current and deterioration of temperature characteristics. Next, when a solution consisting of In, Ga, As, and P was used to grow the second layer, the AI from the first layer growth solution was
Regardless of the carryover amount of Ga, As,
By adjusting the component ratio of P (A12Ga I-Z
)X 1 n 1-zAsy P I-y is Z-0,6
It was confirmed that they grow with a relationship of 6y2+5.48y. The composition determined by EPMA of the thus obtained mixed crystal and the peak wavelength of photoluminescence -13me
Energy gap E at 300K taken as V
g is, for example, tno, ++ (Gao, 5sA10.1
2) 0,59ASO118P0.82 (Eg=1.8
28eV), In0.28(Gao, 62A1o, a
s) 072Aso, 45Po, 55 (Eg=1.743
eV). In these measurements, there was almost no variation in the energy gap, that is, the composition within the plane of the grown layer, and the A from the first layer Ga A, I A s growth solution
It was verified that uniform InGaAIAsP could be grown by carrying over t.

The present invention replaces the conventional GaAlAs active layer, which has a short lifetime particularly in the short wavelength region of 730 nm or less, by using InGaA, which has a long lifetime in long wavelength lasers of 1 μm or more.
InGa'AIAsP active layer with composition similar to sP or InGaAs with 1nGaA, lΔsP as optical guide layer.
By using a P active layer, lifetime characteristics in a short wavelength region are improved, and a practical short wavelength visible light semiconductor laser device is manufactured.

<Embodiment> The drawing is a cross-sectional configuration diagram of a semiconductor laser device showing an embodiment of the present invention. After growing an H-GaAs current confinement layer 2 to a thickness of 0811 m on a (+00) p-GaAs substrate l, a striped groove with a width of 5 μm and a depth of 1 μm is formed by chemical etching using photolithography. . This striped groove portion becomes a current path from which the current confinement layer 2 is removed. Next, p -Gao, 2 A10
．． 8 As cladding layer 3 (thickness outside the groove 0.2 pm),
Non-doped Ino, 2a (Gao, 62A1o, 5s)
o, 72Aso, 45P0.55 active layer 4 (thickness 0.2
pm), n-Gao, 2 AI □, B A
An s-clad layer 5 (thickness: 1 μm) and an n-GaAs cap layer 6 (thickness: 377 m) are sequentially grown by liquid phase epitaxial growth. Next, as the n-side electrode 7, Au-Ge-Ni
, Au--Zn is formed as the p-side electrode 8 by vapor deposition and heating. Through the above steps, a double heterojunction type semiconductor laser device is manufactured. A chip with a cavity length of 250 μm is made of Cu.
The device mounted on the heat sink with an In brazing material oscillated continuously at room temperature at an oscillation wavelength of 720 nm. Further, the threshold current at that time was 186 mA.

In the embodiment described above, a double heterostructure is used that does not include an optical guide layer, but an I
Considering that nGaAIAsP can be grown easily,
It is also possible to adopt a configuration in which a GaAlAs optical guide layer having a smaller energy gap than the cladding layer is grown on the p-ground layer 3, and an InGaAIAsP active layer 4 is grown thereon. In addition, InGaAI is formed on the p-cladding layer 3.
An AsP light guide layer is grown on which an InGaAIAsP active layer with a smaller energy gap than the light guide layer or, in this case, InGa without It; At is grown.
It is also possible to adopt a configuration in which the active layer 4 is made of AsP or the like.

[Brief explanation of drawings]

The accompanying drawing is a configuration diagram of a semiconductor laser device showing an embodiment of the present invention. 1... p-GaAs substrate 2... current confinement layer 3
...p-cladding layer 4...active layer 5...n-
Cladding layer 6... Cap layer 7... Nfill electrode 8... P-side electrode

Claims (1)

[Claims] 1. In a semiconductor laser device having a double heterojunction, the active layer or optical guide layer formed on the GaAlAs layer has five layers of I n * G a + A I , A s and P. A visible light semiconductor laser device characterized in that it is composed of an original mixed crystal. 2. Due to the durability of GaAlAs growth solution, GaAl
On the AS layer, an InGaAIAsP quinary mixed crystal layer to which A1 is added is grown in a liquid phase from an InGaAsP growth solution,
A method for manufacturing a visible light semiconductor laser device, characterized in that the quinary mixed crystal layer is used as an active layer or a light guide layer.