Transparent Rectifying Contacts for Visible-Blind Ultraviolet Photodiodes Based on ZnO

The authors report on the fabrication of transparent rectifying contacts by reactive sputtering of silver or platinum on heteroepitaxially grown zinc oxide. The contacts exhibit Schottky-like current–voltage behavior; the effective barrier height is \(0.73\,\hbox{eV}\) for both materials. In photovoltaic mode, the transparent rectifying contacts reach external quantum efficiencies as high as 32% and responsivities as high as \(0.1\,\hbox{A/W}\).