High UV/visible contrast photodiodes based on epitaxial lateral overgrown GaN layers

Schottky photodiodes have been fabricated on epitaxial lateral overgrown GaN layers, showing a responsivity of 130mA/W. An improvement of one order of magnitude in the UV/visible contrast has been observed, in comparison with devices on standard GaN on sapphire. The significantly lower residual doping concentration reduces markedly the leakage current, and increases the detector bandwidth (> 30MHz in devices with a diameter phi = 200 mu m). Detectivities as high as 5 x 109 Hz(1/2)mW(-1) were obtained in photodiodes with phi = 400 mu m, working at -3.4V bias.