Comparative study of enhancement-mode gallium nitride FETs and silicon MOSFETs for power electronic applications

Gallium nitride (GaN) based high-electron-mobility transistor (HEMT) is becoming popular as fast switching devices for power electronic applications. This paper presents a comparative study of the critical parameters such as on-state resistance, reverse conduction drop, leakage current, maximum junction temperature, threshold voltage, gate charge requirement and device capacitances of commercially available enhancement-mode GaN (e-GaN) devices with those of Si MOSFET devices of the same voltage and current ratings. This paper also calculates the switching transition times of the e-GaN HEMTs based on their gate-charge characteristics. Further, the switching losses are also evaluated. These switching transition times and switching energy losses are also compared for the two types of devices. The e-GaN devices show excellent reduction in switching times and switching losses over the Si MOSFET devices, indicating their suitability for high-frequency power conversion. The e-GaN devices also reduce the on-state loss in most cases. However, the reverse conduction drop and leakage currents are higher with eGaN devices than with Si devices.