A highly UV-selective Schottky-barrier photodiode based on a Ag–GaP contact

Abstract

A Schottky-barrier photodiode with spectral sensitivity in the 300–340 nm region has been prepared successfully using the transmission window of silver and its barrier effect on GaP. Radio-frequency magnetron sputtering has been used for deposition of the silver film. Silver films with thicknesses in the 10–150 nm range exhibit a transmission window at a wavelength of about 320 nm, which can be used as an ultraviolet (UV) bandpass on a GaP photodiode. Furthermore, the Schottky contact of sputtered silver films on n-type GaP grown by liquid-phase epitaxy shows good characteristics, including large barrier heights (1.2–1.3 eV) and low reverse currents (below 2 pA cm−2 at 5 V). The GaP photodiode with a silver Schottky contact exhibits a sensitivity of 0.02 A W−1 at a wavelength of 320 nm. The simplicity of this structure of a UV sensor opens up the possibility for mass production.