Development of Epitaxial AlN/GaN/GaInN Photocathode Heterostructures . for UV/Blue Scintillation and Cherenkov Radiation Detection . ... Photocathode layers consisting of wide-band-gap AlN/GaN/GaInN heterostructures are being compositionally tailored on an atomic scale during the epitaxial crystal growth process to control photoelectron absorption, diffusion, and transport to the negative electron affinity cathode surface. ... The heart of such a device is the photocathode. ...