Si 3 N 4 / AlGaN/GaN –metal–insulator–semiconductor heterostructure field–effect transistors

TLDR

The study reports a metal–insulator–semiconductor heterostructure field‑effect transistor that uses a Si₃N₄ film for both channel passivation and as the gate insulator. The device is fabricated by integrating the Si₃N₄ layer into the heterostructure to serve simultaneously as channel protection and gate dielectric. The Si₃N₄ MISHFET exhibits markedly reduced RF current collapse, four‑order‑of‑magnitude lower gate leakage, and a gate current that rises only from ~90 pA/mm at room temperature to ~1000 pA/mm at 300 °C, with pulsed tests showing the collapse voltage exceeds the threshold voltage.

Abstract

We report on a metal–insulator–semiconductor heterostructure field-effect transistor (MISHFET) using Si3N4 film simultaneously for channel passivation and as a gate insulator. This design results in increased radio-frequency (rf) powers by reduction of the current collapse and it reduces the gate leakage currents by four orders of magnitude. A MISHFET room temperature gate current of about 90 pA/mm increases to only 1000 pA/mm at ambient temperature as high as 300 °C. Pulsed measurements show that unlike metal–oxide–semiconductor HFETs and regular HFETs, in a Si3N4 MISHFET, the gate voltage amplitude required for current collapse is much higher than the threshold voltage. Therefore, it exhibits significantly reduced rf current collapse.