Cryogenic germanium power diode circuit simulator model including temperature dependent effects

Cryogenic testing and physics-based device modeling of a germanium (Ge) power diode for power electronic applications has been conducted. Static and inductive load testing of a 10 A, 250 V Ge diode has been performed with temperatures ranging from ambient (∼ 300 K) to liquid nitrogen (77 K). The device was modeled using the Fourier-series-based solution approach for PvN diodes. The Fourier solution was used in the development of a temperature-dependent physics-based model that can be run using simulation software packages such as virtual test bed (VTB) or PSPICE™. This model has proven to be extremely accurate when applied to silicon based power diodes and similar results have been obtained for the cryogenic Ge diode. Formulas for the temperature dependency of Ge physical parameters, such as mobilities, intrinsic carrier concentration and ionized impurity concentration, are extracted from published data and implemented in the model. Since very limited data is available for the temperature dependence of carrier recombination lifetime, its temperature dependence is extracted from experimental data. Interest in Ge power devices and reliable circuit simulator models is driven by low temperature applications such as deep space exploration, medical diagnostics, and superconductive energy storage.