JPS5939082A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To extend the life of a semiconductor laser by a method wherein the ends of a resonator made of GaAs-GaAlAs base material are coated with ZnSe single crystal thin film. CONSTITUTION:The ends 1a of a resonator made of GaAs-GaAlAs base material are coated with ZnSe single crystal thin film 7. The grid constant of ZnSe single crystal being almost equal to that of GaAs-GaAlAs base single crystal, the adhesion of the thin film 7 to the ends 1a is excellent. Therefore a movable body more stable for a long time as compared with any conventional structure may be provided because the ends 1a are not exposed to the atmosphere at high temperature and humidity, while reducing the possibility of deterioration thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating on the end face of a semiconductor laser, particularly a semiconductor laser made of a 1'CGaAs (gallium arsenide)-CraA7As (gallium aluminum arsenide) based material.

Semiconductor lasers use two opposing surfaces of a resonator, including the active layer, as cleavage planes (hereinafter referred to as end surfaces), and generate laser light with high energy by resonating the light emitted from the active layer between the two cleavage surfaces. force (possible O) Also, the resonator end face is conventionally made of 8102 (silicon dioxide)
, 51 g N4 (silicon nitride), A1203 (aluminum oxide), etc. (crystalline structure; amorphous or polycrystalline) is coated to prevent deterioration of the end face.

However, the material of the above film is GaAs-GaAl! As
Since the crystal structure is completely different from that of the system material, the adhesion is poor, and there is a problem in that the end face deteriorates particularly in a high temperature and humid atmosphere, making it impossible to obtain stable operation for a long time.

The present invention was made in view of the point VC, and its feature is that the resonator end face is coated with a ZnSθ (zinc selenium) single crystal thin film.

The thin Zn5e single crystal has a low optical absorption edge of 48ooX at room temperature, which is similar to GaAs-GaAl! Since the lattice constant is close to that of the As single crystal, it has excellent adhesion with the single crystal. 2VC
The Znse single crystal film can be formed at a low temperature of 400° C. or lower by a molecular beam epitaxial growth method (hereinafter simply referred to as MBE), and its non-doped layer has high resistance.

1 and 2 show one embodiment of the present invention, FIG. 1 is a sectional view taken along the line 1-1' in FIG. 2, and FIG.
It is a sectional view taken along the n' line.

In the figure, (1) is an n-type GaAs substrate whose main surface is the (100) plane, and the substrate has grooves (2) extending perpendicular to the page as shown in FIG. is formed. (3) is the n layer laminated on the -main surface of the substrate (1).
The first cladding layer is of the type Ga 1-xAJxAs (0<X<1), and the first cladding layer is curved concavely on the groove (2) according to the shape of the main surface of the substrate (1).

(41 is an active layer 10 consisting of Ga1-yA, JyAs (0≦Yx1° P-type Ca
(The second cladding layer (6) consisting of -xA/xAs is a cap layer laminated on the second cladding layer and having good ohmic characteristics. The first cladding layer (3), the active layer (4) ), the second cladding layer (5), and the cap layer (6) can be sequentially laminated by epitaaxial growth.

In the praying semiconductor laser, the first and second cladding layers (3) (5
)’s AI! Since the concentration is higher than that of the active layer (4), the cladding layer has a larger C band gap and a smaller optical refractive index than the active layer.

Therefore, the first and second cladding layers (3) (5) and the active layer (
4), a p-light co-former is formed, and the light generated by recombination of electrons and holes in the active layer (4) is amplified while traveling along the groove (2). The resonator end faces (1a) (1a) located perpendicular to the laser beam oscillate as laser light.

f7Jf7J is a non-doped ZnSe single crystal thin film formed on the surface of the end face (ia) (1a), and such a thin film can be formed by MBE. -8
” In a vacuum capacity of T o r r or more, the substrate temperature is 550°C, the Zn saw temperature is 300°C, and the 5ey source temperature is 210°C.
The thickness in the direction perpendicular to the t-plane (1a) (1a)K is preferably λ/2n, where λ is the oscillation wavelength of a given laser and n is the optical refractive index of the ZrlSθ single crystal film.

As mentioned above, when a Zn5e single crystal film is used as a protective film for the open plane (the lattice constant of the ZnS8 single crystal is GaA
Since it is approximately the same as that of the s-GaA/As single crystal, the degree of adhesion to the end face (1a) is high. Therefore, even if the end face (1a) is placed in a high-temperature and humid atmosphere, the end face (1a) will not be exposed to the negative atmosphere, so the risk of deterioration of the VCIFr end face (1a) is reduced, and stable operation for a long time can be obtained compared to the conventional structure. . Furthermore, since the light absorption edge of the Zn5e single crystal is as low as 4900, the laser light is not absorbed and highly efficient light extraction is possible. Furthermore, since the thin film (7) can be grown at low temperatures, there is no risk of crystal defects occurring in the grown layers such as the first and second cladding layers (3) and (5) during the growth of the thin film (7).

Next, the laser of this embodiment and the end face (1a) are made of 51gN4 and Si.
The table below shows the results of a life test when O2 and AJzO3 were used. In the same test, a laser whose end face (1a)+ffi was coated with each of the above materials was immersed in warm water at 50°C.

(Automatic Power Control
) method was used. Specifically, the life (hours) was defined as the time when the drive current increased by 2096 from the initial value with the output fixed at 5 mW.

As is clear from the above table, when Zn5e single crystal is used as the end face (1a) (1a) protective film, 5i5N4τ, 5102
, AI! It can be seen that the lifespan is one to two orders of magnitude longer than using 203 or the like.

As is clear from the above explanation, in the semiconductor laser of the present invention, a long life can be achieved by coating the resonator end face with a ZNSE single crystal thin film.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, and Fig. 1 is 1-1 in Fig. 2.
2 is a sectional view taken along line nm' in FIG. 1. (ia) (1a) -- both 'tia end face, (7
)'('I)-ZnSe single crystal thin film. Figure 1 ■ 1. Diagram 2

Claims (1)

[Claims] (lj A semiconductor laser characterized in that a resonator end face made of GaAs-CaAJAs-based abrasive material is coated with a Zn5e single crystal thin film.