Transient characteristics of drain-source current in response to picosecond pulsed gate-source voltages in AlxGa1-xN/GaN heterojunction field-effect transistors (HFETs) have been measured. It was found that the switching time constants were of the order of tens of picoseconds and depended strongly on the gate-source bias VGS as well as drain-source bias VDS. Slow transients caused by charge trapping effects such as those observed in AlGaAs/GaAs HFETs were absent in AlGaN/GaN HFETs. Our results suggested that the dependence of the effective electron mobility on the sheet density dictates the overall drain current transient characteristics as well as the device switching speed of AlGaN/GaN HFETs.
|Number of pages||3|
|Journal||Applied Physics Letters|
|State||Published - Dec 11 2000|