ZnSe-based Schottky barrier photodetectors

Vertical geometry photodetectors based on n(-)/n(+)-ZnSe structures grown semi-insulating GaAs (001) substrates by molecular beam epitaxy have been realised. A semi-transparent bilayer (Ni (50 Angstrom)-Au (50 Angstrom) 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 1.17eV and a low dark current density of similar to 10(-8) A/cm(2) at -4V 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 (460nm) of 3-4 orders of magnitude.