Imaging devices in the invisible light regions of ultraviolet, infrared and low light level are described and discussed, considering, in particular, the surface problems of photocondutive material. In the MIS blocking junction of a photoconductive target for an ultraviolet vidicon, a thin insulating film of MgF2 on a a-Se photoconductor and SiXNY on a-Si : H are shown to produce interfacial fields increasing sensitivity in short wave length region. In an infrared vidicon with a PbO-S target, it is shown that PbS, which forms a thin sucface layer on the textured Pb0 crystals, plays an important role and brings infrared sensitivity and resistivity sufficiently close to vidicon operation. For low light level use. SiO2-Si interface problems of a silicon intensifier target are described, and new type target with a hydrogenated amorphous silicon to crystalline silicon heterojunction is presented and discussed.
