LINEAR OPTICAL-RESPONSE OF SEMICONDUCTORS

The linear optical constants of photovoltaic semiconductors, that is, their complex dielectric function, are required for the proper choice of materials and the design of photovoltaic devices. Our understanding of the linear dielectric function of semiconductors in the optical region is reviewed using germanium and GaAs as models. Experimental and theoretical results are compared. The discussion is extended to the influence of perturbations such as an applied strain or a finite temperature. Effects of a finite k-vector (spatial dispersion), including birefrigence in cubic materials, are reviewed. Recent data involving stress-induced optical activity of GaAs are presented.