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 130 mA/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 (>30 MHz in devices with a diameter φ=200 μm). Detectivities as high as 5×109 Hz^1/2 mW^-1 were obtained in photodiodes with φ=400 μm, working at -3.4 V bias