Surface wave in a semiconductor substrate with a groundplane

A full-wave and charge transport formulation is applied to the analysis of the dominant TM mode guided by a semiconductor substrate backed by a ground plane. Closed form expressions for the field components, charge density, and current density are obtained, along with characteristic equations for the propagation constant and transverse wave numbers. Numerical results on the wave parameters are obtained for different doping levels. The screening effect of the charge carriers on the transverse component of the electric field is observed to be negligible for an intrinsic semiconductor substrate, but gradually approaching that of a metallic conductor as the doping level reaches 10¹⁸ cm^-3. An equivalent circuit for the structure is constructed to facilitate the development of the dispersion equation while providing physical insight to the process of the wave-charge interaction on the semiconductor surface.