INTERVALENCE BAND ABSORPTION IN BULK INSB LASERS

Four-band Kane theory with the effects of remote bands included via pe rturbation theory has been used to predict the gain spectra in the act ive region of bulk InSb under injection. The effect of intervalence ba nd absorption (IVA) between light and heavy hole bands has been includ ed by calculation from first principles and is found to increase in si gnificance with increasing temperature. Comparison with experimental a bsorption spectra for doped samples shows good agreement indicating th e model's validity. The authors show that to achieve room temperature operation, carrier densities of the order of 5 x 10(18)cm(-3) are requ ired to overcome IVA. Such carrier densities are unlikely to be attain able in bulk devices owing to the large Auger coefficients associated with InSb. Consequently, uncooled laser operation in a device relying on purely bulk InSb properties does not seem practical.