Surface Passivation of AlGaN/GaN HFETs Using AlN Layer Deposited by Reactive Magnetron Sputtering

Abstract

In this paper we show the characteristics of an AlGaN/GaN metal–insulator–semiconductor heterostructure field effect transistor (MISFET) which uses an AlN film as the gate insulator, a passivated MISFET with another layer of AlN over the gate, a regular AlGaN/GaN heterostructure field effect transistor (HFET) and an AlN passivated regular HFET. The AlN insulating layer was deposited by Reactive Magnetron Sputtering. The thickness of each AlN passivation layer is about 50 nm. The gate leakage currents for the MISFET, passivated MISFET, and passivated HFET were much smaller than that for the regular HFET. We observed the current collapse for the regular HFET and the passivated MISFET, unstable DC characteristics for the MISFET, and the suppression of the current collapse for the passivated HFET.