Recessed AlGaN/GaN Heterojunction-based Hydrogen Sensor Operated by Reverse Bias Mode

A Pt-functionalized hydrogen sensor was fabricated on a recessed AlGaN/GaN heterojunction platform where the thickness of the recessed AlGaN barrier layer under the Pt catalyst was 10 nm. Sensing characteristics were investigated under two different bias modes: forward and reverse bias operations. Unlike conventional diode type sensors, the recessed heterojunction sensor exhibited superior sensing characteristics under the reverse bias operation mode in comparison to the forward bias operation mode. The thin AlGaN barrier layer enhanced the field emission process under reverse bias operation, thus enabling a high response, which had another benefit of significantly lowering standby power consumption compared to the forward bias operation mode. A response of ~870 % and a response time of ~11 sec were achieved at 200°C with a standby power consumption of 0.03 W/cm2.