JPH0224393B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field This invention relates to a semiconductor laser device, and particularly to improvement of its heat dissipation characteristics. (b) Prior Art Since a semiconductor laser device is a high-power device driven by current, it generates a large amount of heat during operation. Therefore, if an appropriate heat dissipation design is not carried out, there is a risk that the heat generated during energized use may lead to performance deterioration, shortened element life, or destruction of the semiconductor laser element. Specifically, semiconductor laser elements generally have temperature characteristics as shown in FIG. As is clear from the figure, the light emission output largely depends on the element temperature. To obtain an optical output of 2 mW at a temperature of 20°C, a current of approximately 30 mA is required, but when used at a temperature of 50°C, a current of 30 mA is required.
mA cannot even reach laser oscillation,
A drive current of 60 mA or more is required to obtain an optical output of 2 mW. Furthermore, if the drive current is increased to compensate for the decrease in optical output due to temperature rise, the increase in current will cause an increase in the amount of heat generated by the element, creating a vicious cycle in which the element temperature will further rise. , leading to rapid deterioration of the device and, in extreme cases, destruction of the device. Therefore, the stem supporting the semiconductor laser element needs to be made of a material with high thermal conductivity to improve heat dissipation. Furthermore, if there is a difference in the coefficient of thermal expansion between the stem and the semiconductor laser element, distortion occurs due to heat generation, and unnecessary stress is applied to the semiconductor laser element. Such stress accelerates the deterioration of the performance of the semiconductor laser device and even causes its destruction. Therefore, the material for the stem is required to have high thermal conductivity and a coefficient of thermal expansion as close as possible to that of the semiconductor laser element. Therefore, conventionally, as shown in FIG. 1, a semiconductor laser element 1 was attached to a block 3 in a mount of a package via a submount 2, and the submount 2 was made of a material with low thermal expansion such as Kovar (trade name). The practice was to use materials that exhibit specific properties. (c) Problems to be Solved by the Invention As mentioned above, the material of the submount 2 is required to have good thermal conductivity and a coefficient of thermal expansion close to that of the semiconductor laser element 1. However, as shown in Table 1, the conventionally used Kovar has a coefficient of thermal expansion very close to that of semiconductor laser element 1, but it has a problem of low thermal conductivity, and this has made it difficult to improve the performance of semiconductor lasers. This was a major obstacle. (d) Means for solving the problem The present invention is directed to a semiconductor laser using a semiconductor laser element having a substrate of GaAs, GaP, or GaSb, and in this case, the material of the submount has a thermal expansion coefficient of 5.0 or more. The following metals in the range of 8.5×10 ^-6 cm/cm・℃, namely (1) Alloy containing W and Cu uniformly (2) Alloy containing Mo uniformly containing Cu (3) W・It was decided to use one of the alloys in which Cu is uniformly contained in a Mo alloy. The above alloys can be manufactured by an infiltration method. If the material of the submount exceeds the above-mentioned range of coefficient of thermal expansion, the mismatch in coefficient of thermal expansion with the semiconductor laser element will become large, and the stress generated on the element will cause damage to the element or a decrease in luminous efficiency. Further, the Cu content of the metal material satisfying the thermal expansion coefficient in the above range is as follows in weight %. W + Cu: 0.5 to 30% (metal material in (1) above) Mo + Cu: 5 to 35% (metal material in (2) above) W・Mo+Cu: 0.5 to 35% (metal material in (3) above) The thermal conductivity of metal materials is 0.35~
It is 0.70 cal/cm・sec・℃. A comparison between the metal material of the present invention and a conventional example (Kovar) and the coefficient of thermal expansion of the element substrate are shown in Table 1 below for reference.

[Table] As can be seen from Table 1 above, in the case of the present invention, the coefficient of thermal expansion is extremely close to that of the element substrate of a semiconductor laser device, and the thermal conductivity is about 10 times that of conventional Kovar, compared to tungsten and molybdenum. This is an improvement of about 40-70%. (e) Example Semiconductor laser devices in which a semiconductor laser device with a double heterostructure in which AlGaAs was epitaxially grown on a GaAs substrate were fixed to various submounts and stems shown in Table 2 were fabricated, and their performances were compared. I went there.

【table】

[Table] In other words, the temperature rise of the element of this semiconductor laser device is reduced by about 25 to 35% compared to the device using conventional Fe-Ni (Kovar), and the luminous efficiency is 70 to 80%.
%, the lifespan has increased approximately 100 times. It was confirmed that the higher the Cu content, the better the heat dissipation characteristics. (f) Effects As described above, according to this invention,
A semiconductor laser device with good heat dissipation and less stress caused by heat generation can be obtained. Also, the third
As shown in the figure, we were able to easily create a package structure in which the submount, mounting block, and stem were integrated.

[Brief explanation of drawings]

FIG. 1a is a top view showing a conventional semiconductor laser device, and FIG. 1b is a sectional view taken at AA'. Second
The figure is a drawing showing an example of the light emission characteristics of a semiconductor laser. FIG. 3a is a top view showing an example of the semiconductor laser device of the present invention, and FIG. 3b is a sectional view at BB'. The meanings of each number in the figure are as follows. The same numbers indicate corresponding parts in each drawing. 1: semiconductor laser element, 2: submount,
3: Mounting block material, 4: Light extraction window, 5:
Cap, 6: Package body or stem;
7: First lead wire, 8: Second lead wire, 9:
Insulator, 10: Lead wire.

Claims (1)

[Claims] 1. In a semiconductor laser device consisting of a semiconductor laser element whose substrate is GaAs, GaP or GaSb,
W, Mo are used as submount and stem materials.
Or by infiltration method into either W-Mo alloy
Uniformly contains Cu and has a thermal expansion coefficient of 5.0 to 8.5×
A semiconductor laser device characterized by using an alloy whose thermal conductivity is adjusted to within the range of 10 ^-6 cm/cm・℃, and in which a submount and a stem are integrally molded.