p-Type conductivity in the delafossite structure

Compounds of the type CuMO2 and AgMO2 have been doped in various ways to induce p-type conductivity. Most of the compounds have the delafossite structure which can exist in 2H and 3R polytypes. Both the 2H and 3R forms of CuScO2 have been intercalated with oxygen up to a formula of CuScO2.5. p-Type conductivity can also be induced in CuScO2 by substitution of Mg for Sc. Thin films of CuScO2 prepared by rf sputtering are transparent and show a conductivity of 30 S cm(-1). Thin films of Mg-doped CuCrO2 are transparent and show a room-temperature conductivity of 220 S cm(-1). Doping of AgMO2 compounds with M=Sc, In, Cr, and Ga have produced p-type conductivity, but never higher than about 0.01 S cm(-1) at room temperature. (C) 2001 Elsevier Science Ltd. All rights reserved.