Gallium nitride metal-semiconductor-metal photodetectors prepared on silicon substrates

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 359 nm, the maximum responsivities of the n(-)-GaN MSM photodetectors with TiW and Ni/Au contact electrodes were 0.187 and 0.0792 A/W, corresponding to quantum efficiencies of 64.7% and 27.4%, respectively. For a given bandwidth of 1 kHz and a given bias of 5 V, the corresponding noise equivalent powers of our n(-)-GaN MSM photodetectors with TiW and Ni/Au electrodes were 1.525x10(-12) and 5.119x10(-12) W, respectively. Consequently, the values of detectivity (D-*) determined for devices with TiW and Ni/Au electrodes were then calculated to be 1.313x10(12) and 3.914x10(11) cm Hz(0.5) W-1, respectively.