The mechanism of radio-frequency current collapse in GaN–AlGaN heterojunctionfield-effect transistors(HFETs) was investigated using a comparative study of HFET and metal–oxide–semiconductor HFET current–voltage (I–V) and transfer characteristics under dc and short-pulsed voltage biasing. Significant current collapse occurs when the gate voltage is pulsed, whereas under drain pulsing the I–V curves are close to those in steady-state conditions. Contrary to previous reports, we conclude that the transverse electric field across the wide-band-gap barrier layer separating the gate and the channel rather than the gate or surface leakage currents or high-field effects in the gate–drain spacing is responsible for the current collapse. We find that the microwave power degradation in GaN–AlGaN HFETs can be explained by the difference between dc and pulsed I–Vcharacteristics.
Published in Applied Physics Letters, Volume 78, Issue 15, 2001, pages 2169-2171.
©Applied Physics Letters 2001, American Institute of Physics (AIP).
Tarakji, A., Simin, G., Ilinskaya, N., Hu, X., Kumar, A., Koudymov, A., Yang, J., Khan, M. A., Shur, M. S., & Gaska, R. (9 April 2001). Mechanism of Radio-Frequency Current Collapse in GaN-AlGaN Field-Effect Transistors. Applied Physics Letters, 78 (15), 2169-2171. http://dx.doi.org/10.1063/1.1363694