Modelling the key material properties of germanium for device simulation in cryogenic environments.

Germanium is commonly suggested as an alternative for power electronic devices in emerging liquid hydrogen applications. Despite the clear benefits of a twofold conductivity increase and fabrication familiarity within the community, very few models exist, which describe the temperature-dependent electrical characteristics of the material. Here, models are presented and adapted, which describe the temperature and doping dependence of the carrier concentration, mobility, and velocity from room temperature down to 20 K. For each of these, closed-loop models are adapted, which can be readily used in technology computer-aided design (TCAD) software, and new models are introduced when required. For high-field applications, the carrier velocity has been independently considered for both the ⟨100⟩ and ⟨111⟩ directions with the introduction of a new model for electrons in the ⟨100⟩ direction. With the work conducted here, it is now possible to simulate and predict the performance and suitability of germanium electronics for emerging low- and high-power applications