The Influence of Internal Interfaces on Charge-Carrier Diffusion in Semiconductor Heterostructures

Abstract

The ongoing miniaturization of semiconductor devices renders charge-carrier transport along interfaces increasingly important. The characteristic length scales in state-of-the-art semiconductor technology span only a few nanometers. Consequently, charge-carrier transport inevitably occurs directly at interfaces between adjacent layers rather than being confined to a single material. Herein, charge-carrier diffusion is systematically studied in prototypical active layer systems, namely, in type-I direct-gap quantum wells and in type-II heterostructures. The impact of internal interfaces is revealed in detail as charge-carrier diffusion takes place much closer to or even across the internal interfaces in type-II heterostructures. Type-I quantum wells and type-II heterostructures exhibit comparable diffusion rates given similar inhomogeneous exciton linewidths. Consequently, the changes in the structural quality of the interfaces are responsible for changes in diffusion and charge-carrier transport along interfaces rather than the existence of the interfaces themselves.