ZnSe-based Schottky barrier photodetectors

Vertical geometry photodetectors based on n^-/n⁺ -ZnSe structures grown on semi-insulating GaAs (001) substrates by molecular beam epitaxy have been realised. A semi-transparent bilayer (Ni(50 Å)-Au (50 Å)) was used to form the Schottky contact. The current-voltage characteristics show that the devices have an ideality factor of 1.1, a barrier height of 1.17 eV and a low dark current density of ~10^-8 A/cm² at -4 V bias. These photodetectors have a flat responsivity above the bandgap (measured to be 0.1 A/W) and a sharp cutoff at the band edge (460 nm) of 3-4 orders of magnitude