Schottky barrier photodetector based on Mg‐doped p‐type GaN films

In this letter we report the fabrication and characterization of Schottky 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 current‐voltage and capacitance‐voltage characteristics were measured for Ti/Au Schottky barriers for a film with a p doping of 7×1017 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 be 0.13 A/W. For these photovoltaic detectors, the photoresponse was nearly constant from 200 to 365 nm and fell sharply by several orders of magnitude for wavelengths above 365 nm.