Nanocrystalline <i>p</i>-type transparent Cu–Al–O semiconductor prepared by chemical-vapor deposition with Cu(acac)2 and Al(acac)3 precursors

Abstract

P-type transparent copper–aluminum–oxide semiconductor films are prepared by the use of the chemical-vapor deposition (CVD) technique with Cu(acac)2 and Al(acac)3 precursors. Transmission electron microscopy and electron diffraction suggest that the films contain nanocrystalline phases of CuAlO2 and Cu2O, in which CuAlO2 is dominant. Both Hall technique and Seebeck measurement reveal that the film is p type, and a very high room-temperature conductivity of 2 S cm−1 is achieved. This success of high-conductive p-type transparent semiconductor using CVD further paves the way for transparent semiconductor p–n junctions as well as industrial mass production of the relevant devices. The Hall measurement of the film shows a sheet mobility of 0.16 cm2 V−1 S−1 and a carrier concentration of 1.8×1019 cm−3. A wide optical gap of 3.75 eV due to quantum confinement is found, and the activation energy for the positive holes is 0.12 eV.