Ensemble Monte Carlo modeling of quantum cascade detectors

We present a method to perform accurate and efficient simulations of photovoltaic quantum cascade detector (QCD) structures based on the ensemble Monte Carlo (EMC) approach. Since the photocurrent is typically orders of magnitude smaller than the pump current in a quantum cascade laser (QCL), a direct application of QCL simulation techniques is not sufficiently accurate. We demonstrate that by exploiting thermodynamic equilibrium relations for the electron populations and scattering rates, the EMC method can be adapted to yield reliable results for the essential QCD figures of merit, such as responsivity and specific detectivity. The modeling approach is validated against available experimental results for various mid-infrared and terahertz QCD designs and furthermore compared to simulations based on the non-equilibrium Green's function method.