Carrier distribution in graded-band-gap semiconductors under asymmetric band-edge gradients

Abstract

The authors have discussed earlier the photomagnetoelectric effect in graded-band-gap semiconductors assuming symmetrical band-edge gradients. The present paper rewrites the continuity equation under asymmetric band-edge gradients, and includes the effects of position-dependent minority carrier lifetime, electron and hole mobilities, and effective masses. A study of excess minority carriers as a function of position in the direction of graded composition indicates that under steady photoexcitation, minority carrier distribution and total concentration of carriers are markedly dependent on the relative magnitudes of conduction- and valence-band-edge gradients. A plausible physical explanation of the carrier distribution in the graded-band-gap specimen has been attempted.