Threshold Voltage Instability Measurement Circuit for Power GaN HEMTs Devices

The p gallium nitride (GaN) gate-based GaN high-electron mobility transistors (HEMTs) devices are preferred to achieve normally- off operation in power electronic applications. However, this type of device suffers from threshold voltage instability. That instability is typically characterized using a curve tracer. The curve tracer is unable to provide shorter pulsewidth lesser than 500 $\mu$ s. This drawback restricts the characterization of the device operating at a higher frequency. In order to address this issue, a half-bridge circuit with a series-connected capacitor is proposed. The half-bridge allows for achieving shorter pulsewidth, whereas the capacitor provides transient current. Using these two features of the circuit, an EPC2014C device is characterized, and the instability in threshold voltage is reported.