Numerical evaluation of Auger recombination coefficients in relaxed and strained germanium

The potential applications of germanium and its alloys in infrared silicon-based photonics have led to a renewed interest in their optical properties. In this letter, we report on the numerical determination of Auger coefficients at T = 300 K for relaxed and biaxially strained germanium. We use a Green's function based model that takes into account all relevant direct and phonon-assisted processes and perform calculations up to a strain level corresponding to the transition from indirect to direct energy gap. We have considered excess carrier concentrations ranging from 1016 cm−3 to 5 × 1019 cm−3. For use in device level simulations, we also provide fitting formulas for the calculated electron and hole Auger coefficients as functions of carrier density.