Correlation between the EFG Values Measured at the Cd Impurity in a Group of Cu-based Delafossites and the Semiconducting Properties of the Latter

Abstract

In this paper we analyze trend of EFG values measured at Cd impurity in a group of semiconducting delafossites with chemical formula CuBO 2 (B = Al, Fe, Cr, Nd). We conclude that this trend reveals one of the most subtle details in electronic spectrum of the compounds: if impurity states are formed within or out of the band gap. In CuAlO 2 and CuFeO 2 the Cd EFG exhibits larger value than in CuCrO 2 and CuNdO 2 , when Cd substitutes the Cu atom. This occurs because in the first two compounds the Cd forms shallow band within the gap, and in the second two compounds does not. When Cd occupies the B position it exhibits almost the same EFG in all delafossites. In this case, Cd does not form its states within the gap in none of the compounds. To arrive to these conclusions we analyzed and calculated various systems (Cd-doped CuAlO 2 and CuCrO 2 compounds, fictitious molecules), using the FP-LAPW method.

Reactive SputteredWide-Bandgap p-Type Semiconducting Spinel AB2O4 and Delafossite ABO2 Thin Films for “Transparent Electronics”

“…Several groups theoretically calculated the effects on the electronic behavior of the material due to the presence of various cations in Cu and/or Al sites. Lalić et al [188][189][190] showed that Cd and Zn substitutions on Cu site would produce n-type conductivity in the material, whereas Ni doping in Cu sites would enhance the p-type conductivity of the material. But Cd doping on Al sites would have no effect on the electrical properties of the material.…”