Optical Properties and Switching Behaviour of Excited III–V Semiconductors near the Direct–Indirect Cross‐Over

Abstract

Abstract In highly excited semiconductor systems near the transition from direct to indirect band structure (cross‐over) the energetic distance between different conduction band minima is a nonmonotonous function of the excitation intensity. A theoretical explanation of this experimental result is given. Our investigations are based on the evaluation of photoluminescence spectra using a careful lineshape analysis. The nonmonotony is a consequence of the unequal shrinkage of the direct and indirect gaps as a function of the population of energetically comparable conduction band valleys in a material near cross‐over. In the situation discussed an optical switching mechanism is expected, which is explained with special respect to its switching time. Important problems of electron–electron interaction are discussed.