Enhanced Hydrogen Detection Sensitivity of Semipolar GaN Schottky Diodes by Surface Wet Etching on Schottky Contact

Abstract

We report on the enhanced hydrogen sensing characteristics of surface-etched Pt Schottky diodes fabricated on semipolar GaN films using photo-electrochemical wet etching. The surface-etched Pt Schottky diodes showed a rapid sensing response to 4% hydrogen, as well as a full recovery to their initial current level after removing the hydrogen from the ambient. They also demonstrated stable and reproducible current changes with a reasonable linearity in response to H2 concentrations of 0.5∼4% in increments of 0.5%. The hydrogen sensitivity of Pt Schottky diodes on semipolar GaN could therefore be improved by incorporating surface etching on the Schottky contact area using KOH solutions. This rough surface is expected to improve hydrogen detection sensitivity due to the presence of more available adsorption sites, resulting in effective variations of the Schottky barrier height.