Pt - Al Ga N ∕ Ga N Schottky diodes operated at 800°C for hydrogen sensing

Abstract

Schottky diodes on AlGaN∕GaN heterostructures with Pt catalytic metal are fabricated and characterized from 200to800°C for H2 sensing. Over this large range of temperature, the forward current of Schottky diodes increases with exposure to H2 gas, which is attributed to the reduction of Schottky barrier heights resulting from hydrogen absorption in the catalytic metal. The results indicate that AlGaN∕GaN heterostructure Schottky diodes are capable of high-temperature operation for H2 sensing up to 800°C. As temperature increases, the hydrogen detection sensitivity of Pt–AlGaN∕GaN Schottky diodes improves due to the more effective H2 dissociation. When the testing ambient is changed from N2 to 5% H2/95% N2, the value of the Schottky barrier height decreases by 11 and 120meV at 200 and 800°C, respectively.