Reflected second harmonic in degenerate semiconductors: nonlinear electroreflection under surface degeneracy conditions

A phenomenological theory is developed and experiments are reported on generation of a reflected second harmonic in degenerate semiconductors when an electric field is applied to the surface. An analysis is made of the case of bulk degeneracy and of the degeneracy of carriers in a surface layer when a space charge region appears after application of a static field. A relationship is established between the field dependence of the intensity of the reflected second harmonic and the state of the surface of a semiconductor, such as the thickness and dielectric properties of an oxide film, surface charge (density of the surface states), etc. Nonlinear electroreflection is considered as a new experimental method for the investigation of the surfaces of centrosymmetric semiconductors.