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 ~ 0.02 Ω-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.