MULTIVARIABLE DEPENDENCE OF MODULATION SPECTROSCOPY IN SEMICONDUCTOR SUPERLATTICES

The modulation spectrum of semiconductor superlattices is shown to be a sensitive function of photon wavelength and local energy band-bendin g in the superlattice structure. The added dependence leads directly t o the concept of a modulation spectroscopy surface for heterostructure s as opposed to a simple plot in two dimensions of amplitude as a func tion of photon energy. The implications of these results for the use o f modulation spectroscopy methods such as contactless photoreflectance spectroscopy, where the band bending cannot be controlled, are discus sed. (C) 1997 American Institute of Physics. [S0003-6951(97)03343-3].