Evaluation of turn-off dV/dt controllability and switching characteristics of 1.2 kV GaN polarisation superjunction heterostructure field-effect transistors

Abstract

Gallium Nitride (GaN) devices inherently offer many advantages over silicon power devices including higher operating frequency, lower on-state resistance, and higher operating temperature capabilities, which can enable higher power density, more efficient power electronics. Turn-off dV/dt controllability plays a key role in determination of common-mode voltage in electrical drives and traction inverters applications. The fast-switching edges of GaN can introduce challenges such as electromagnetic interference, premature insulation failures and high overshoot-voltages. In this paper, the device working principle, characteristics and dV/dt controllability of 1.2kV GaN polarisation superjunction (PSJ) heterostructure field effect transistors (HFET) are presented. The effect of gate driving parameters and load conditions on turn-off dV/dt are investigated. It is shown that, in PSJ HFETs, the dV/dt can be effectively controlled to as low as 1kV/µs by controlling the gate and with minimum increase in switching losses. These results are highly encouraging for their application into the motor drives.