It is known that the recombination mechanism in narrow-band-gap semiconductor lasers is dominated by the Auger process. An attempt to use the intersubband transitions in the superlattice for lasers is thus restricted by the Auger recombination process. The intersubband Auger recombination process is different from the conduction to valence-band Auger process since the subbands have different band structures, resulting in a different overlap integral and probability weighting function. The probability weighting function is comparable to that of the valence to conduction-band Auger process for narrow-band-gap (0.3 eV) bulk material. The overlap integral can be reduced by adjusting the miniband bandwidth. However, there is a tradeoff in controlling the bandwidth for a lower Auger rate (requiring narrower bandwidth) and for a larger carrier injection (requiring wider bandwidth). A closed form of the intersubband Auger rate is derived. It gives a much weaker band-gap and temperature dependence. Due to the adjustable overlap integral, the intersubband Auger rate can be made much lower than that of the conventional conduction to valence-band transition of the same band gap.
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