The effect of intervalence band absorption on the thermal behavior of InGaAsP lasers

Measurements of intervalence band absorption spectra were made in p-type In
0.53
Ga
0.47
As, InP, and GaAs. The measured spectra are broader, have less temperature dependence, and have 2× less peak intensity than theoretical curves predicted by an elementary
k\cdotp
band model. For
p = 10^{18}
cm
^-3
, all three crystals have absorption coefficients of about 13 cm
^-1
at 1.3 μm and 25 cm
^-1
at 1.6 μm. These values of absorption should also be applicable as estimates of intervalence band absorption in quaternary laser material. Because of the low strength and weak temperature dependence of the intervalence band absorption, it should have only a minor effect on the temperature dependence of laser threshold. For example, using our absorption data, we calculate that intervalence band absorption will reduce the experimental temperature parameter T
0
of 1.3 μm quaternary lasers from 194 to 179 K.