Schottky contact on hydrothermally grown a-plane ZnO for hydrogen sensing and UV detection

• Pt Schottky contact on a-plane ZnO film grown by a hydrothermal method was studied.
• The effect of ZnO crystal polarity on Schottky barrier height was investigated.
• Hydrogen sensing and UV detection of a-plane ZnO Schottky diode were evaluated.

Pt Schottky contact on nonpolar a-plane ZnO film grown by a simple hydrothermal method on a-plane GaN was investigated. The Schottky barrier height was measured to be 0.64 eV at room temperature and atmospheric pressure. The effect of ZnO crystal polarity on Schottky barrier height was studied, and the barrier height of a-plane ZnO was compared to the values of c-plane in the literature. Also, hydrogen sensing and UV detection characteristics of a-plane ZnO Schottky diode were evaluated. After exposure of 4% hydrogen in nitrogen, the diode showed current increase due to Schottky barrier height reduction, and 2006% of maximum sensitivity to hydrogen gas was observed. For repeated UV illumination, the Schottky contact presented stable and recoverable current response.