The sensing performance of hydrogen gas sensor utilizing undoped-AlGaN/GaN HEMT (a)

Abstract

High temperature operation and long term stability are important requirements for gas sensor. The response of Pt-circular Schottky diodes fabricated on undoped AlGaN/GaN high-electron-mobility-transistor (HEMT) structure to hydrogen gas at various temperatures, ranging from 25 to 200°C has been investigated. A 5 nm-thick of catalytic Pt Schottky contact is formed by electron beam evaporation. Both forward and reverse currents of the device increase upon exposing to hydrogen gas. Although a slight change of forward and reverse current is obtained at room temperature upon exposure to hydrogen but both currents drastically increase with the increase of temperatures. The time-transient characteristics show the average current increment and decrement speed of 27.6 and 17.6 nA sec-1, respectively at constant forward bias of 1 V and temperature of 200°C.