Comparison of GaN Schottky barrier and p-n junction photodiodes

At present, the main efforts in fabrication of UV photodetectors are directed to GaN Schottky barriers and pn junction photodiodes. The future development of UV photodetectors will be dominated by complex band gap heterostructures using 3-dimensional gap and doping engineering. AlGaN exhibits extreme flexibility, it can be tailored for optimised detection at important region of UV spectrum, and multicolor devices can be easily constructed. The comparative study of GaN Schottky barriers (with a n-type material) and p-n junction photodiodes are carried out in more details. Due to the fact that the built-in voltage of a Schottky diode is smaller than that of a pn junction, the saturation current of a Schottky barrier is considerably higher than that of pn junction. Special attention has been devoted on analysis of current responsivities of both types of detectors. Owing to relative simplicity in fabrication of Schottky barriers, they can be more promising than pn junction detectors, especially in the case of low doping ensuring the entire depletion of the n-type layer.