Effects of longitudinal field on transmitted near field in doped semi-infinite semiconductors with a surface conducting sheet

Abstract

A unique structure composed of a half-space of air and a semi-infinite doped bulk GaAs covered by an InAs conducting interface sheet is proposed, from which the physics behind the interplay between the effects of transverse sheet current and the longitudinal three-dimensional plasma waves, as well as the effect of evanescent modes, can be explored. The in-plane and perpendicular components of a transverse field are modified by the inclusion of the InAs conducting sheet and a longitudinal field, and the coupling between transverse and longitudinal oscillations of an electromagnetic field parallel and perpendicular to the conducting sheet is made possible by the doped GaAs bulk. Based on this structure, a spatially nonlocal dynamic theory is derived, including the coupling between the transverse and longitudinal oscillations, the image-potential and retardation effects, and the effects of evanescent modes. The existence of the InAs conducting sheet is found to reduce the transmitted field by reflection from the induced sheet current. The longitudinal field is found to further reduce its strength by absorption from an induced longitudinal three-dimensional plasma wave in the doped GaAs bulk. The transmitted near field is modified by the doped electrons in the GaAs bulk with a relative enhancement at small incident angles being overshadowed by the strong reflection from the induced sheet current in the InAs conducting sheet on the surface.