Hydrogen sensitive Schottky diode using semipolar (112¯2) AlGaN/GaN heterostructures

In this work, we investigated the hydrogen sensing characteristics of Pt Schottky diodes using semipolar (112¯2) AlGaN/GaN structures. First, these diodes showed a large current change of 30 mA at 1 V upon the introduction of 4% hydrogen in nitrogen gas with an accompanying Schottky barrier reduction of 90 meV at 25 °C. Second, their hydrogen detection sensitivity peaked at the zero bias voltage, and slowly decreased with applied bias voltage. Third, they demonstrated stable and reproducible current changes with a reasonable linearity in response to H2 concentrations from 0.5 ∼ 4% with a step of 0.5%. As such, Pt Schottky diodes on semipolar AlGaN/GaN structures hold great promise for highly-sensitive hydrogen sensors due to their surface polarity and atomic configuration.