Air-Annealing Effects for Pt/Ti Gate Si-Metal–Oxide–Semiconductor Field-Effect Transistors Hydrogen Gas Sensor

Abstract

Air-annealing Pt (15 nm)/Ti (5 nm) gate Si-metal–oxide–semiconductor field-effect transistors (Si-MOSFETs) at 400 °C for 2 h revives and enhances the hydrogen sensing activity of nearly all the inert sensor characteristics of the Pt (15 nm)/Ti (5 nm) gate Si-MOSFETs. The sensing amplitudes are changed from 0.0–0.16 V to 0.82–0.96 V under the air-diluted 1000 ppm-hydrogen gas exposure before and after the air annealing. A transmission electron microscope (TEM) and Auger analysis clearly show that one of the causes is the novel mixing of nanocrystalline TiOx and super heavily oxygen-doped amorphous Ti in the Ti-layer formed on the gate oxide SiO2.