Cadmium stannate conductive layer with high optical transmittance and tunable work function

Abstract

200 nm cadmium stannate (Cd2SnO4) transparent conductive layer films with a sheet resistance of 6.35 Ω/sq and resistivity of 1.27 × 10−4 Ω · cm are deposited by magnetron sputtering coupling with adjustable target bias voltage followed by 620 °C 30 min annealing. The lowest resistivity of Cd2SnO4 films reported before was 1.28 × 10−4 Ω · cm, achieved with 510 nm Cd2SnO4. The average transmission rate of 200 nm sputtering Cd2SnO4 films between 400–800 nm is 94%. The deposition rate increase target bias voltage can the and electrical performance of Cd2SnO4 films. The surface work function of Cd2SnO4 films is also tunable by target bias voltage. The Cd2SnO4 phonon spectrum and phonon density of states combined with Raman microscope shows the Cd2SnO4 films with most ideal electric properties has a identical phonon response. XPS shows the chemical component of as-deposited Cd2SnO4 films and Cd2SnO4 films after annealing with 120 V target bias voltage is Cd2.03SnO6.36 and Cd1.25SnO4.15, respectively, which is contrary to the general conclusions that interstitial cadmium atoms and oxygen vacancies are the main self-doping defects in Cd2SnO4 films.