Moisture Insensitive PMMA Coated Pt-AlGaN/GaN Diode Hydrogen Sensor and Its Thermal Stability

Abstract

Poly(methyl methacrylate) (PMMA) encapsulated Pt-AlGaN/GaN Schottky diodes show highly sensitive (100 ppm, 0.01% by volume) room temperature detection of hydrogen and are insensitive to the presence of water in the sensing ambient. These diodes show no physical degradation or loss of sensitivity when repeatedly cycled (50 x, 1 min hold at each temperature) between 25-100 degrees C. There is complete selectivity for hydrogen sensing over other gases, including CO, CO2, NO2, O-2 and CH4. The PMMA encapsulation provides an effective and robust barrier to moisture, greatly increasing the range of environments in which the sensors can be used. (C) The Author(s) 2018. Published by ECS.