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Gallium nitride (GaN) ultraviolet metal-semiconductor-metal photodetectors (PDs) grown on Si substrates were demonstrated. The dark current of PDs fabricated on Si substrates was substantially smaller in magnitude compared to identical devices prepared on sapphire substrates. With an incident wavelength of 359nm, the maximum responsivities of the n−‐GaN MSM photodetectors with TiW and Ni∕Au contact electrodes were 0.187 and 0.0792A∕W, corresponding to quantum efficiencies of 64.7% and 27.4%, respectively. For a given bandwidth of 1kHz and a given bias of 5V, the corresponding noise equivalent powers of our n−‐GaN MSM photodetectors with TiW and Ni∕Au electrodes were 1.525×10−12 and 5.119×10−12W, respectively. Consequently, the values of detectivity (D*) determined for devices with TiW and Ni∕Au electrodes were then calculated to be 1.313×1012 and 3.914×1011cmHz0.5W−1, respectively.

Vertically well-aligned ZnO nanowire ultraviolet (UV) photodetectors were fabricated by spin-on-glass technology on ZnO:Ga/glass templates. With 2V applied bias, it was found that dark current density of the fabricated device was only 2.0×10−7A∕cm2. It was also found that UV-to-visible rejection ratio and quantum efficiency of the fabricated ZnO nanowire photodetectors were more than 1000 and 12.6%, respectively.