Extraction Method of 2DEG Charge from Gate-Capacitance Characteristics of Normally-OFF p-GaN/AlGaN/GaN HEMTs

Abstract In this work, we propose a method for extracting the channel two-dimensional electron gas (2DEG) density from the gate capacitance-voltage (C_G-V_G) characteristics of p-GaN/AlGaN/GaN High Electron Mobility Transistors (HEMTs). Unlike conventional AlGaN/GaN HEMTs, the variation of 2DEG density with gate voltage in a normally-OFF p-GaN gated HEMT cannot be directly obtained from the integration of the C_G-V_G characteristics due to the charge leakage from the gate. Our proposed extraction method incorporates the practical charge leakage mechanisms, and its accuracy is validated against results from a well-calibrated TCAD tool and experimental data. Notably, we also demonstrated that the charges obtained by integrating the C_G-V_G characteristics of p-GaN gated HEMTs represent a weighted average of both the 2DEG charge and the Schottky depletion charge at the gate metal/p-GaN contact.