Study on breakdown characteristics of AlGaN/GaN-based HFETs

GaN-based devices are gaining popularity due to its high electrical performance and are widely used in high frequency and high power microwave applications. Unfortunately, there are limitations faced by HFETs which are current leakage and breakdown characteristics which affect the performance of the device. This work focuses on the investigation of geometrical and process variation impact on the electrical characteristics and breakdown voltage of the AlGaN/GaN based High Field Effect Transistor (HFET). The Sentaurus Technology Computer Aided Design (TCAD) by Synopsys was used to facilitate this study on the electronics properties of the HFET specifically the current density in the two-dimensional electron gas (2DEG) channel, carrier mobility, band energy and transfer characteristics. It has been observed that process variations specifically substrate material selection have significant impact on the performance of the HFET as compared to geometric variation. HFETs with the Silicon Carbide substrate demonstrate higher breakdown voltage as compared to the conventional silicon substrate. Optimization of the conventional structure by means of introducing silicon carbide as the substrate demonstrates an increase of 183.33% in terms of breakdown voltage.