Analytical description of electric field profile in heterojunctions

We propose a model that describes the electric field profile as it extends into the GaAs layer of a modulation-doped AlGaAs-GaAs structure. This closed-form analytical expression is obtained from an accurate two-dimensional electron gas (2DEG) sheet density model and is particularly suitable for simulating the effects of absorption modulation on the spectral response of multilayer photodetectors. A significant improvement in model accuracy is achieved by introducing an exponential coefficient that provides a closer description of the electric field profile behavior near the heterointerface where field strengths are highest. Results are compared with device simulation programs.