Gate pulse frequency‐dependent kink effects in GaAs metal‐semiconductor field‐effect‐transistors with a low‐temperature‐grown buffer layer

Two kinds of kink effects (abrupt increases in pulsed drain current ID) were observed in GaAs metal–semiconductor field‐effect transistors (MESFETs) with a buffer layer grown by molecular‐beam epitaxy at low substrate temperature of 300 °C (LTB), when pulsed voltage trains with swinging range from threshold voltage to 0 V and 10% duty cycle were applied to gate electrode. These kink effects were not observed in dc measurement; however, they appeared with increasing frequency of those gate pulse trains. One kink effect is observed at 100 μs of the pulse width of high level Wh with the pulsed ID increase of 11% (first kink). Overshoot observed in the transient wave form suggests that this first kink effect is attributed only to capture of excess number of holes, which are generated by impact ionization along channel, into the hole trap of LTB. The lifetime of these holes is estimated to be 100 μs at least in the LTB from the discussion. The other kink effect is observed at 10 μs of Wh with the pulsed ID inc...