Electrical engineering

Physics

Engineering

Voltage

Nanotechnology

Transistor

Wide-bandgap semiconductor

Materials science

Threshold voltage

Instability

Gallium nitride

Layer (electronics)

Optoelectronics

Mechanics

IEEE Transactions on Electron Devices

We investigate the impact of the gate contact on the threshold voltage stability in p-GaN gate AlGaN/GaN heterojunction field-effect transistors with double pulse measurements on the p-GaN gate devices and device simulations. We find that, under gate stress, in the case of high-leakage Schottky contact, a negative threshold voltage shift results from hole accumulation in the p-GaN region. Conversely, in the case of low-leakage Schottky contact, hole depletion in the p-GaN region gives rise to a positive threshold voltage shift. More generally, we show that an imbalance between the hole tunneling current through the Schottky barrier and the thermionic current across the AlGaN barrier results in a variation of the total charge stored in the p-GaN region, which in turn is responsible for the observed threshold voltage shift. Finally, we present a simplified equivalent circuit model for the p-GaN gate module.

Threshold Voltage Instability in p-GaN Gate AlGaN/GaN HFETs