Fabrication of high-density electron-doped 12CaO·7Al₂O₃ thin films by physical and chemical processes

Abstract

12CaO·7Al₂O₃ (C12A7) crystal is a constituent of alumina cements and an electrical insulator having a wide bandgap of ∼7 eV. When high-density electrons were doped into C12A7 by replacing the O^2- ions in its crystallographic cages with electrons almost exclusively (C12A7:e^-), they exhibited metallic conduction with a small work function of ∼2.4 eV, making the C12A7:e^- attractive for use in electronic devices. This article focuses on comparing two fabrication methods for the C12A7:e^- thin films: ion implantation of inert gas ions and a reduction reaction using an oxygen deficient amorphous C12A7 layer. Further, their respective electrical and optical properties are discussed.