Enhanced carrier concentration of Fe doped delafossite CuAlO2 by double-effect: Divalent metal ions doping and excess oxygen

Abstract Bulk CuAlO 2 compound has been widely studied as a p-type metal oxide semiconductor material due to the simplicity in its synthesis and use of inexpensive raw materials. The Fe doping in CuAlO 2 has been demonstrated to enhance the electrical conductivity. An in-depth analysis of the effect of Fe doping in CuAlO 2 on the carrier concentration improvement was revealed. Delafossite CuAl 1−x Fe x O 2 powders with x  = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.30 were synthesized by a solid-state reaction method. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) studies were used to measure the atomic-ion concentrations and the oxidation state of each element. The variations of carrier concentration corresponded with a ratio of Cu 2+ /Cu 1+ in CuAlO 2 . We found that the increase of Cu 2+ /Cu 1+ was caused by double effects through divalent metal ions (Fe 2+ ) doping and excess oxygen (O 2−δ ) in CuAlO 2 . The maximum carrier concentration of 8.09 × 10 17  cm −3 was obtained for the CuAlO 2 sample at Fe content of 10 at.%.