THEORY OF ENHANCED HYPER-RAMAN SCATTERING FROM INHOMOGENEOUS SEMICONDUCTOR SURFACES - EFFECTS OF CARRIER SCATTERING AND SPATIAL-DISPERSION

We present the theory of hyper-Raman scattering of light (HRS) from la ttice vibrations in an inhomogeneous surface region of a semiconductor . Inhomogeneities due to surface band bending associated with carrier depletion or accumulation layers are considered. Large inhomogeneities induce local changes of sign in the dielectric permittivity and conse quent large enhancements of HRS intensity. The role of carrier scatter ing and spatial dispersion is discussed together with possible extensi ons of HRS spectroscopy to Schottky barriers and Ohmic contacts and th e development of a novel scanning HRS spectroscopy.