Effects of annealing temperature on sensing properties of Pt/HfO2/SiC Schottky-diode hydrogen sensor

Hafnium oxide (HfO₂) is successfully used as gate insulator for fabricating metal-insulator-SiC (MISiC) Schottky-diode hydrogen sensor. Sensors undergone N₂ annealing at different temperatures are fabricated for investigation. The hydrogen-sensing properties of these samples are compared with each other by taking the measurements at high temperature under various hydrogen concentrations using a computer-controlled measurement system. Experimental results show that sensitivity increases with the annealing temperature. Higher annealing temperature can enhance the densification of the HfO₂ film; improve the oxide stoichiometry; and facilitate the growth of a SiO₂ interfacial layer to give better interface quality, thus causing a remarkable reduction of the current of the sensor under air ambient. The effects of hydrogen adsorption on the barrier height and hydrogen-reaction kinetics are also investigated.