Correlation between p-type conductivity and electronic structure of Cr-deficient CuCr1-xO2 (x = 0-0.1)
Journal
Physical Review B
Journal Volume
86
Journal Issue
24
Pages
241103
Date Issued
2012
Author(s)
Singh, Shashi B.
Yang, L. T.
Wang, Y. F.
Shao, Y. C.
Chiou, J. W.
Lin, K. T.
Chen, S. C.
Wang, B. Y.
Chuang, C. H.
Ling, D. C.
Pong, W. F.
Tsai, M. H.
Tsai, H. M.
Pao, C. W.
Shiu, H. W.
Chen, C. H.
Lin, H.-J.
Lee, J. F.
Yamane, H.
Kosugi, N.
Abstract
The correlation between the p-type hole conduction and the electronic structures of Cr-deficient CuCr1-xO2 (x=0-0.1) compounds was investigated using O K-, Cu, and Cr L3,2-edge x-ray absorption near-edge structure (XANES), scanning photoelectron microscopy, and x-ray emission spectroscopy measurements. XANES spectra reveal a gradual increase in the Cu valence from Cu1+ to Cu2+ with increasing Cr deficiency x, whereas, the valence of Cr remains constant as Cr3+. These results indicate that the p-type conductivity in the CuCr 1-xO2 samples is enhanced by a Cu1+-O-Cu2 + rather than a Cr3+-Cr4+ or direct Cu1 +-Cu2+ hole mechanism. Remarkable Cr-deficiency-induced changes in the densities of Cu 3d, Cu 3d-O 2p, and O 2p states at or near the valence-band maximum or the Fermi level were also observed. In addition, a crossover of conduction mechanism from thermally activated (TA) hopping to a combination of TA and Mott's three-dimensional variable range hopping occurs around 250 K. © 2012 American Physical Society.
Type
journal article