JPS58176990A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain a long life semiconductor laser which does not show any thermal deterioration and crystal distortion due to difference of thermal expansion coefficients and also has excellent heat radiating characteristic, by forming a buried layer of cap layer with a Ca-doped ZnSe. CONSTITUTION:A buried layer 7 of a cap layer 6 in a semiconductor laser is composed of a Ca-doped ZnSe and therefore it has a lattice constant and thermal expansion coefficient which are almost equal respectively to that of an oscillating layer 2 consisting of GaAl As system material. Therefore, crystal distortion is not generated in the oscillating layer 2 and thermal deterioration is also not generated in the oscillating layer 2 because ZnSe can be grown even under a temperature as low as 400 deg.C by the molecular beam epitaxial growth method. Moreover, since ZnSe has a very high thermal conductivity, there is no fear of generating breakdown of semiconductor laser due to a heat generated during continuous oscillation. In addition, since a buried layer 7 consisting of ZnSe to which Ga is added is n type, electrode is respectively formed on the surface of cap layer 6 and rear side of substrate 1 and a forward bias is applied across these electrodes. As a resutl, the buried layer 7 substantially has a high resistance value. Therefore, an applied current is squeezed by the buried layer 7 and the main current path is formed just under the cap layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor radar, in particular, a striped cap layer formed on an oscillation layer including an active layer that causes radiative recombination, and which is made of a material with excellent ohmic characteristics and has substantially high This invention relates to a semiconductor radar surrounded by a buried layer serving as a resistor.

FIG. 1 shows a typical radar of this type, (II is an ntMGIAI (gallium arsenide) substrate whose entire surface is a (100) plane, (2) is an oscillation layer formed on the substrate, and the oscillation The layers are the first cladding layer (3) consisting of n-type (@ t -XAAXAII (gallium aluminum arsenide) (0<X<1), Ga + -yjuyAs (0≦Y<
1, x>Y) active layer (4), P-type Gi 11
The second cladding all (5) made of AAXAs is sequentially epitaxially grown and laminated.

In the praying oscillation layer (2), both the Crabstone layers (31 (5)) located above and below the active layer (4) have a higher hta degree than the active layer (4), so the band gap is larger than that of the praying active layer (4). , ° and the optical refractive index is small, so the active layer (4
Holes and electrons are well confined within the active layer (
) is a stripe-shaped cap layer formed on the second cladding layer (5) and extending in the direction perpendicular to the plane of the drawing.
) are formed to make a good ohmic connection with electrodes to be formed in the future, and are made of PHMGaAs. The buried layer is conventionally made of high resistance material, such as 5i.
(It is composed of h.

In a praying semiconductor radar, electrodes are formed on the surface of the camp layer (6) and the back surface of the substrate (1), and when a forward bias is applied between both electrodes, the applied current flows through the buried layer (the path is narrowed by the force and the passage is approximately the cap layer). (6), therefore, single-transverse mode Radical light is oscillated at a low current in the active layer (4) directly under the cap layer (6).

However, the thermal expansion coefficient of 5102 forming the buried layer (7) is α35X10''/'K, whereas that of G-AtAs forming the second cladding layer (5) is approximately 6.OX10''/'K. Therefore, there is a problem that crystal distortion occurs in the second cladding layer (5) and the like due to such a difference in thermal expansion coefficients.

In addition, normally in semiconductor radars, the cap layer (6) side is fixed to the heat sink in order to improve heat dissipation, but 5iC
h means that the heat generated in the ninth oscillation layer (2), which has a low thermal conductivity of α014 W/m・℃, will not be transferred to the heat sink and will accumulate in the laser, causing thermal damage to the semiconductor radar. One possible way to solve this problem is to use GaAs, which has a substantially high resistance, as the material for the layer (7), but when growing GaAs, the molecular beam epitaxial modification method, which can grow at the lowest temperature, is considered. Even if a semiconductor layer (4) is used, it is necessary to expose the semiconductor radar to a high temperature of 600°C, and at such high temperatures, the active layer (4) once grown is 41 km long.
There is a problem that physical deterioration occurs and the life span is shortened.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a semiconductor radar which is free from thermal deterioration and crystal distortion due to a filtering of the AM tensile coefficient, and which has an excellent heat dissipation effect. The lattice incorporation of Zn5e (zinc selenium) made of a zinc blende type n-w compound, the coefficient of thermal expansion is 5.667λ, 7.
sb at 2 x 10-'10K, the praying value is GaAtA
They are almost the same as those of Hatake.Moreover, when ZaSe is grown by an improved molecular beam epitaxial method, it can be formed at low humidity below 400℃.Furthermore, when Ga (gallium) is added as an impurity to Zn5e, its thermal conductivity increases. It has also been found that the thermal conductivity of non-doped Zn5e increases.
5 to 0.6 W15N・℃, and Ga is <10”e
That of Zn5e added to the extent of ta-” is t2W/
For reference, the thermal conductivity of 1cGaAs is 0.54 W/cm·°C.゛The present invention was made based on this knowledge, and its feature is that the above-mentioned buried layer (Zn5 containing Ga as an impurity)
The buried layer (7) made of Zn5e can be formed by molecular beam epitaxial growth, and new growth is performed at a substrate temperature of 350°C in a vacuum chamber evacuated to a vacuum level of 10'Torr or less. , Zn cell temperature 300°C, Se cell temperature 210°C, Ga cell temperature 6
The test was carried out for about 30 minutes at 00°C. As a result, a ZaSe layer with a carrier concentration of about 5 μm was grown on the surfaces of the cap layer (6) and the second cladding layer (5).

Since the ZaSe layer formed on the cap layer (6) is unnecessary, it is removed by etching with a NiOH aqueous solution after the growth.

Note that the carrier concentration of Zn5e can be increased by increasing the temperature of the Ga cell.

The buried layer (7) of the cap layer (6) in the semiconductor radar of this embodiment is made of FiGa-doped Zn5e, and has approximately the same lattice constant and thermal expansion coefficient as the oscillation layer (2) made of G1AtAs-based material. (2) No crystal strain occurs within the oscillation layer (2), and since Zn5e can be grown at a low temperature of 400°C using the molecular beam epitaxial modification method, no thermal deterioration occurs within the oscillation layer (2). . Furthermore, since Zn5e has extremely high thermal conductivity, there is no risk of damage to the semiconductor radar due to heat generated during continuous oscillation.

In addition, a buried layer made of Zn5e doped with Ga (the force is n-type, so the cap layer (6) surface and the substrate (1)
When a forward bias is applied between the electrodes forming the back tfiK dog electrode, the buried layer (7) Vi becomes a substantially high resistance layer. Therefore, the applied current is inserted into the buried layer (by force), and the main current path is directly under the camp layer (6) as in the conventional case.

While the lifespan of conventional semiconductor lasers made of buried six-layer TSI (h, GaAs, etc.) was several thousand hours, the lifespan of this example laser was 15,000 hours. , shows another embodiment of the present invention, and its feature is that the present invention is applied to a C3P (channel substrate brainer) type semiconductor laser.The same reference numerals are given to the same parts as in Fig. 1. There is.

The same effect as in the first embodiment can be obtained using a semiconductor laser.

Note that the present invention is not applicable only to the nine-structure semiconductor laser shown in the embodiment, but is applicable to TS (terrace substrate)
It is also applicable to electrode stripe type devices such as semiconductor radars.

As is clear from the above description, since the buried layer of the camp layer of the semiconductor laser of the present invention is made of Zn5s of Ga dog, a long life can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a typical semiconductor radar, and FIG. 2 is a sectional view showing an embodiment of the present invention.
s (semiconductor) substrate, (2)... oscillation layer, (6)...
... Cap layer, (7) ... Buried layer. Figure 1 Figure 2

Claims (1)

[Claims] (1) Semiconductor substrate, GaAtA layered on the substrate
an oscillation layer made of S material, a stripe-shaped cap layer laminated on the oscillation layer and made of a semiconductor material with good ohmic characteristics, and a buried layer arranged on both sides of the cap layer, consisting of nine buried layers 11 containing Ga as an impurity. Do Z
A semiconductor laser characterized by the characteristics of n5e.