High electron doping to a wide band gap semiconductor 12CaO•7Al2O3 thin film

High-density electrons (similar to 1.9x10(21) cm(-3)) were doped into a polycrystalline film of a wide band gap (similar to 7 eV) semiconductor 12CaO center dot 7Al(2)O(3) (C12A7) by an in situ postdeposition reduction treatment using an oxygen-deficient C12A7 overlayer. The resultant film exhibits metallic conduction with a Hall mobility of similar to 2.5 cm(2) V-1 s(-1) and a conductivity of similar to 800 S cm(-1). Optical analyses indicate that most of the doped electrons behave as free carriers with an effective mass of 0.82m(e) and the estimated in-grain mobility is 5.2 cm(2) V-1 s(-1), which agrees reasonably with the value obtained for high-quality single crystals. (C) 2007 American Institute of Physics.