High-Sensitivity Mid-Ultraviolet Pt/Mg_0.59Zn_0.41O Schottky Photodiode on a ZnO Single Crystal Substrate

Abstract

A Pt/Mg0.59Zn0.41O Schottky photodiode on a ZnO single crystal is reported. The Mg0.59Zn0.41O film was deposited on a ZnO single crystal substrate by an RF magnetron sputtering method. The optical bandgap of the Mg0.59Zn0.41O film obtained from the spectral transmittance and reflectance, was 4.6 eV. The fabricated photodiode consisted of an anti-reflection SiO2 film, semitransparent Schottky Pt electrode, Mg0.59Zn0.41O film, n+-ZnO single crystal substrate and Pt/Ti ohmic electrode. The ideality factor of the photodiode, obtained from the current–voltage characteristics, was 1.3. The maximum responsivity was 0.015 A/W at the wavelength of 220 nm.