Size-induced metal-insulator transition in metals and semiconductors

Abstract We report on the size-induced metal-insulator transition discovered in tiny metal crystals. Here the electric conductivity drastically decreases with particle diameter below a few μm. On the other hand, in semiconductor crystallites a size-correlated inter-band absorption blue shift was observed. The effects are a consequence of the quantum confinement in all three dimensions (“quantum dots”) and hence are of universal character. In addition to their fundamental importance, the observations now allow the design of the ultimate microelectronic device and permit the engineering of novel devices as well.