Effects of Effective Mass Anisotropy and Effective Mass Difference in Highly Photoexcited Semiconductors

Abstract

We analyze the effects of effective mass anisotropy and the effective mass difference between electrons and holes on the electron–hole ( e – h ) BCS state in highly excited semiconductors at various temperatures. The present analysis is based on the BCS-like pairing theory for finite temperatures. We find that, at sufficiently low temperatures, the e – h BCS state is stable even in the case of differing electron and hole effective masses. On the other hand, the difference in effective mass anisotropy between electrons and holes significantly suppresses the e – h BCS order. We have also found that, in the case where electrons and holes have the same mass anisotropy, the e – h BCS order becomes more stable with increasing the anisotropy.