A fast detector by discontinuous metal film for the millimeter through optical frequency range

Metal-to-metal (M-I-M) point contact diodes are used as mixers and detectors for precise frequency measurement of lasers in submillimeter and infrared regions. They, however, are not so stable for mechanical and electric shocks and their lifetimes are short. In order to overcome these defects, discontinuous metal films deposited by vacuum evaporation are proposed to get stable M-I-M junctions, and discontinuous platinum-palladium-alloy films superposed on a discontinuous gold films showed good performance as fast detectors for millimeter wave and CO2 laser signals. The comparison of detection properties of various frequencies showed that the detection was caused by the nonlinearity of the thin film, that is, by the nonlinearity of the tunneling effect between metal islands.