Electrical transport and structural study of CuCr1-xMgxO2 delafossite thin films grown by pulsed laser deposition

The growth and properties of delafossites CuCr1-xMgxO2 thin films are examined. These films are grown by pulsed laser deposition. As a class of materials delafossites have received recent interest since some members show p-type behavior. While not considered true wide-bandgap materials due to a narrow indirect bandgap that fails to adsorb light due to a forbidden same parity transition, optical transparencies greater than 40% in the visible can be observed. In order to be useful for transparent device applications, CuCr1-xMgxO2 films are needed with low resistivity and high optical transparency. Epitaxial films of CuCr1-xMgxO2 were grown on c-sapphire, examining the effects of oxygen pressure and growth temperature on film properties. Films were realized with resistivity of similar to 0.02 Omega-cm and optical transparency of 40% in the visible. The formation of a problematic secondary minority spinel phase of (Cu,Mg)Cr2O4 is discussed. While conductivity increases substantially with Mg doping, the incidence of the spinel phase increases as well. (C) 2008 Elsevier B.V. All rights reserved.