JPH0222881A - Manufacture of double-heterostructure semiconductor laser - Google Patents

Abstract

PURPOSE:To enhance an element characteristic by a method wherein, after an InGaAsP active layer has been formed, an extremely thin InP growth layer is formed in an InP solution whose supersaturation at a prescribed temperature is comparatively high and an InP clad layer is formed in a next InP solution in order to make an interface between the InGaAsP layer and the InP layer flat. CONSTITUTION:An InGaAsP active layer is formed in a growth substrate 1 under an InGaAsP solution 2; after that, the substrate 1 is passed under a wash melt 3 at a speed of 60mm/sec. The substrate is kept under a solution 4 for clad layer use; an InP clad layer is grown. During this process, a temperature at which the substrate 1 is passed under the wash melt 3 is set at 615 deg.C; stocking amounts of In and InP in the wash melt 3 are set at about 16g and about 106mg, respectively. That is to say, a supersaturation of the wash melt 3 during this process is adjusted to, e.g., 8 deg.C out of 6 to 10 deg.C. When the substrate 1 passed under the wash melt 3, an InP growth layer of about 0.02mum is formed. Accordingly, even when the supersaturation of the solution for clad layer use is low, a meltback is not caused. In a semiconductor laser formed in this manner, a threshold current can be reduced by about 10%.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a semiconductor laser in which a grown film is formed by liquid phase epitaxial growth. Regarding the Aa method.

[Conventional technology]

Conventionally, when manufacturing a semiconductor laser using a liquid phase epitaxial growth method, a growth substrate 1 is placed on a sliding slider boat (slider plate) 6 as shown in FIG. After contacting the solution 2 to form an active layer, it is passed under a so-called wash melt 3, and then In is formed in a cladding growth layer solution 4.
A P cladding layer was formed.

Here, the dust melt 3 is for preventing a part of the InGaAsP solution As from being mixed into the clad growth layer solution 4 when the growth substrate 1 is slid. This wash melt 3 is usually selected to have the same composition as the cladding growth layer solution 4. The cladding growth layer solution 4 is required to have a low degree of supersaturation for the purpose of increasing the thickness control of the cladding growth layer, so both the cladding layer solution 3 and the cladding growth layer solution 4 are usually kept at a temperature of about 1 to 6°C. It was adjusted to be supersaturated.

[Problem to be solved by the invention]

However, the InGaAsP once formed on the growth substrate 1
If the supersaturation degree of the active layer is as low as 6°C or less in wash melt 3, a very slight meltback occurs, and the interface between the InGaAsP active layer and the InP cladding layer causes microscopic waviness. It turned out that there was.

For this reason, semiconductor lasers having these growth layers have a problem in that scattering loss of light propagating through the active layer increases and device characteristics deteriorate.

The purpose of the present invention is to solve such problems and to
An object of the present invention is to provide a method for manufacturing a double hetero type semiconductor laser in which device characteristics are improved by flattening the interface between the sP layer and the nPJffl.

[Means to solve the problem]

The method for manufacturing a double hetero type semiconductor laser of the present invention includes I
The growth substrate on which the nGaAs active layer is formed has a high degree of supersaturation and an effective degree of supersaturation that does not easily cause precipitation is 6 to 1.
The method is characterized in that it includes a step of contacting the substrate with an InP growth solution at a temperature of 0° C., and then bringing the substrate into contact with the next InP growth solution to form an InP cladding layer.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a growth substrate 1 is grown using an InGaAsP solution A.
After forming active As in InGaAsP under 200 ms, the growth substrate 1 is passed under the Owashmelt 3 at a speed of 60 mm/sec. Thereafter, the InP cladding layer is grown while being kept under the cladding layer solution 4. At this time, the temperature at which the growth substrate 1 passes under the wash melt 3 is 615° C., and the amounts of In and InP added to the wash melt 3 are 16 g and 106 mg, respectively. That is, the supersaturation degree of the wash melt 3 at this time is adjusted to about 8°C.

Here, when the growth substrate 1 passes under the wash melt 3, an InP growth layer of about 0.02 μm is formed.

Therefore, meltback does not occur even if the supersaturation level of the next cladding layer solution is low. Further, since the degree of supersaturation of the wash melt 3 is as high as 8° C., meltback of the InGaAsP active layer does not occur. The semiconductor laser manufactured in this manner was able to reduce the threshold current by about 10% compared to conventionally manufactured devices.

In addition, in this example, the Owashmelt 3 with the growth substrate 1 is
Although it was mentioned above that the substrate is passed under the wash melt 3 for one second, the same effect can be obtained by sliding the substrate under the next cladding growth layer solution 4. In this case, under the same temperature and wash melt charge conditions as in this example, InPWI in the wash melt was
will be formed approximately Q, (') 47zm,
The same improvement effect as in this example was observed in the characteristics of the element.

[Effect of the invention] As described above, the production method of the present invention
After forming the sP active layer, a very thin InP growth layer is formed in an InP solution with a relatively high degree of supersaturation at 6 to 10°C, and then an InP cladding layer is formed in the next Inp solution to form an InGaAsP layer. It prevents meltback in the InP solution, eliminates microscopic waviness at the boundary between the InGaAsP active layer and the InP cladding layer, and reduces scattering loss of semiconductor laser light within the device. This has the effect of improving device characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a part of a general liquid phase epitaxial growth apparatus. DESCRIPTION OF SYMBOLS 1... Growth substrate, 2... InGaAsP active layer growth solution, 3... Oschmelt, 4... InP cladding layer growth solution, 5... Molten tank, 6... Slider plate.

Claims (1)

[Claims] The growth substrate on which the InGaAs active layer is formed has an effective supersaturation degree of 6 to 6, which has a high supersaturation degree and does not easily cause precipitation.
A method for manufacturing a double hetero type semiconductor laser, comprising the steps of bringing the substrate into contact with an InP growth solution at a temperature of 10°C, and then bringing the substrate into contact with a subsequent InP growth solution to form an InP cladding layer. .