Heterostructure modeling considerations for Ge-on-Si waveguide photodetectors

The computer-aided design and optimization of Ge-on-Si pin waveguide photodetectors is usually performed by a multiphysics approach, where carrier transport is described with the drift-diffusion model. This paper addresses the shortcomings of such a description applied to the study of the n-on-p detector configuration, ascribes them to the overly simplified model of the Si/Ge heterojunction, and proposes an enhanced description of the interfacial region based on technological considerations. The benefits of this more realistic model on the determination of the electrooptic response are discussed and demonstrated.