Fabrication of bipolar CuInO2 with delafossite structure Original Research Article

The crystal structure, electrical behaviors and band structure of new delafossite-type CuInO2, which was newly synthesized in our previous study, were investigated to compare with those of isostructural CuAlO2. The structure of CuInO2 is rhombohedral, and its lattice parameters are larger than those of CuAlO2. CuAlO2 shows both p-type semiconductor with a conductivity of 6.7×10−5 S m−1 at 600 K, which is smaller than that (9.4×10−2 S m−1) of CuAlO2, and n-type semiconductor with a conductivity of 4.4×10−1 S m−1 at 600 K. The band structure calculations based on the density functional theory indicate that CuInO2 is a semiconductor having a 0.49 eV indirect band gap. The bands lying near the Fermi level of CuInO2 are mainly made up from the Cu-3d and O-2p wave functions.