THIN-FILM DIAMOND UV PHOTODETECTORS - PHOTODIODES COMPARED WITH PHOTOCONDUCTIVE DEVICES FOR HIGHLY SELECTIVE WAVELENGTH RESPONSE

Silicon-supported and free-standing thin films of diamond have been us ed to fabricate photoconductive and photodiode structures for the dete ction of UV light. On free-standing (80 mu m thick) material, a planar interdigitated design with 20-mu m electrode spacings is found to off er unprecedented wavelength discrimination between deep UV and visible light, with dark currents <0.1 nA, when a methane-air gas treatment i s used. On silicon-supported (6 mu m thick) films, a planar photodiode utilising gold Schottky and Ti-A-Au ohmic contacts also offers a shar p cut-off in photo-response in the deep UV with no measurable dark cur rent; photoconductive devices fabricated on this material do not show useful levels of performance. The characteristics of each type of devi ce are discussed.