PHOTOLUMINESCENCE STUDIES OF N-I-P-I SUPERLATTICES IN INSB AND INAS -SUPPRESSION OF AUGER RECOMBINATION DUE TO TYPE-II POTENTIALS

Infrared photoluminescence (pi) from InAs and InSb n-i-p-i superlattic es grown by MBE has been found for the first time and has been studied over an extended temperature range. Quantum confined band-to-band tra nsitions are observed at lambda similar to 6.5 mu m and lambda similar to 12 mu m for an InSb n-i-p-i and lambda similar to 3.6 mu m for an InAs n-i-p-i, representing a reduction of more than 50% and 20% from t he bulk bandgap values respectively. A blue shift of 20 meV in the eff ective bandgap of the InSb n-i-p-i is observed on increasing the excit ation from 0.3 W cm(-2) to 1.6 W cm(-2). In contrast to bulk narrow-ga p samples, the n-i-p-i luminescence conversion efficiency is remarkabl y stable against the effects of increasing temperature (only a twofold decrease between 14 and 77 K) and this is attributed to the suppressi on of the dominant Auger recombination mechanism by the type II n-i-p- i band structure.