Metal-semiconductor-metal GaN ultraviolet photodetectors on Si(111)

GaN metal-semiconductor-metal photoconductive detectors have been fabricate d on Si(111) substrates. The GaN epitaxial layers were grown on Si substrat es by means of metalorganic chemical-vapor deposition. These detectors exhi bited a sharp cutoff at the wavelength of 363 nm and a high responsivity at a wavelength from 360 to 250 nm. A maximum responsivity of 6.9 A/W was ach ieved at 357 nm with a 5 V bias. The relationship between the responsivity and the bias voltage was measured. The responsivity saturated when the bias voltage reached 5 V. The response time of 4.8 ms was determined by the mea surements of photocurrent versus modulation frequency. (C) 2000 American In stitute of Physics. [S0003-6951(00)03327-1].