Theoretical analysis of photogating in InP nanowire arrays with embedded InAsP quantum discs

In this contribution, we analyze the photogating effect in InP nanowire arrays with embedded InAsP quantum discs by detailed numerical modeling. The model comprises a drift-diffusion current coupled to the nonlinear Poisson equation, solved on a 2-dimensional geometry with rotational symmetry. By comparison to experimental data, surface trap states are identified that explain both the current versus voltage behavior in dark and under illumination. The current versus illumination power is highly nonlinear, and shows measured gain up to 320 for a power of 20 nW at 980 nm for an array of millions of wires.