Structural, optical, and electrical properties of conducting p-type transparent Cu-Cr-O thin films

Cu-Cr-O films were prepared by DC magnetron co-sputtering using Cu and Cr targets on quartz substrates. The films were then annealed at temperatures ranging from 400 degrees C to 900 degrees C for 2 h under a controlled Ar atmosphere. The as-deposited and 400 degrees C-annealed films were amorphous, semi-transparent, and insulated. After annealing at 500 degrees C, the Cu-Cr-O films contained a mixture of monoclinic CuO and spinel CuCr2O4 phases. Annealing at 600 degrees C led to the formation of delafossite CuCrO2 phases. When the annealing was further increased to temperatures above 700 degrees C, the films exhibited a pure delafossite CuCrO2 phase. The crystallinity and grain size also increased with the annealing temperature. The formation of the delafossite CuCrO2 phase during post-annealing processing was in good agreement with thermodynamics. The optimum conductivity and transparency were achieved for the film annealed at approximately 700 degrees C with a figure of merit of 1.51 x 10(-8) Omega(-1) (i.e., electrical resistivity of up to 5.13 Omega-cm and visible light transmittance of up to 58.3%). The lower formation temperature and superior properties of CuCrO2 found in this study indicated the higher potential of this material for practical applications compared to CuAlO2. (C) 2016 Published by Elsevier Ltd and Techna Group S.r.l.