SCHOTTKY-BARRIER PHOTODETECTOR BASED ON MG-DOPED P-TYPE GAN FILMS

In this letter we report the fabrication and characterization of Schot tky barrier photodetectors on p-type GaN films. These films were grown over basal plane sapphire substrates using low pressure metalorganic chemical vapor deposition and magnesium as the p-type dopant. The curr ent-voltage and capacitance-voltage characteristics were measured for Ti/Au Schottky barriers for a film with a p doping of 7 X 10(17) cm-3. We measured a 1.5 V forward turn on and a 3 V reverse breakdown. The zero bias responsivity of a detector with 1 mm2 area was measured to b e 0.13 A/W. For these photovoltaic detectors, the photoresponse was ne arly constant from 200 to 365 nm and fell sharply by several orders of magnitude for wavelengths above 365 nm.