Normally-off thin-film silicon heterojunction field-effect transistors and application to complementary circuits

A thin blocking structure is incorporated in the gate-stack of heterojunction field-effect transistor (HJFET) devices to substantially suppress the gate current when the gate heterojunction is forward-biased. As a result, normally-off HJFET devices with MOSFET-like characteristics are obtained. The HJFET devices are comprised of gate, source, and drain regions formed by plasma-enhanced chemical vapor deposition on thin-film crystalline Si substrates at temperatures below 200 ̂ C. The on/off ratios larger than 106 , operation voltages as low as 1 V, and subthreshold slopes of ∼ 85 mV/decade are demonstrated. The HJFET devices can be integrated with MOSFET devices fabricated on the same crystalline Si substrates to form complementary circuits. © 2014 IEEE.