(Al,Ga)N ultraviolet photodetectors and applications

The structure and characteristics of AlGaN-based UV photodetectors are pres ented. Photoconductive, Schottky barrier, and metal-semiconductor-metal dev ices with Al mole fractions of up to 35% have been fabricated, showing cuto ff wavelengths that shift from 365 to 290 nm. Photoconductive detectors are non-linear with incident power and have very slow time response tails, whi le photodiodes are quite linear, and their time response is limited by the device resistance-capacitance product. Some material issues related to phot odetector design are discussed. Solar UV monitoring and biological applicat ions are described.