AnIn_0.52Al_0.48As+-In_xGa_1-xAs heterostructure field-effect transistor with anIn-enriched channel

摘要

In_0.52Al_0.48As+-In_xGa_1-xAs HFETs have been fabricated with InAs fractionsbetween 0.53 and 0.7 in the channel. These HFETs, also called MIDFETs(metal-insulator doped-channel FETs), have a doped channel and anundoped wide-bandgap insulator. The enhancement of InAs in the channelresults in a marked improvement in transconductance and peak draincurrent. Devices with L_g=1 μm and x=0.7display an unprecedented I_d of 656 mA/mm and g_m of 296 mS/mm. As x is increased, however,there is an increase in the gate current, a dramatic decrease in thebreakdown voltage, and a degradation of pinch-off. Leakage at thegate-mesa edge overlap is found to be partially responsible for theseeffects. To achieve the substantial gains in transport that higher InAsfractions offer, better isolation technology is required