Physical Modeling of Quasi-ballistic GaN HEMTs Operating at Cryogenic Temperatures

This abstract presents a physical model to describe the current-voltage response of quasi-ballistic GaN HEMTs operating at ultra-low temperatures up to the cryogenic limit (4.2 K). The model includes various sources of carrier scatterings, such as due to interface roughness and phonons, as well as the temperature-dependent thermal conductivity of the heterostructure to make realistic assessments of the merits of GaN technology at ultra-low temperatures. The model is validated in the temperature range of 77 K to 300 K using a judicious mix of measurement data and technology computer-aided design (TCAD) simulations. The model is further applied to predict the device's I-V curves, transconductance, and cut-off frequency at 4.2 K over a broad bias range. The model presented here offers critical insights into the role of temperature and heterostructure design of GaN HEMTs when used in an extremely low-temperature environment. Additionally, the model can be integrated into a circuit simulation framework to facilitate the design of cryogenic GaN-based control circuitry that can be interfaced with quantum computing hardware.