The effect of nitrogen on the properties of zinc nitride thin films and their conversion into p-ZnO:N films

Zinc nitride thin films were deposited by magnetron sputtering using ZnN target in plasma containing either N-2 or Ar gases. The rf-power was 100 Wand the pressure was 5 mToff. The properties of the films were examined with thermal treatments up to 550 degrees C in N-2 and O-2 environments. Films deposited in Ar plasma were opaque and conductive (p similar to 10(-1) to 10(-2) Omega cm, N-D similar to 10(18) to 10(20) cm(-3)) due to excess of Zn in the structure. After annealing at 400 degrees C, the films became more stoichiometric, Zn3N2, and transparent, but further annealing up to 550 degrees C deteriorated the electrical properties. Films deposited in N-2 Plasma were transparent but very resistive even after annealing. Both types of films were converted into p-type ZnO upon oxidation at 400 degrees C. All thermally treated zinc nitride films exhibited a shoulder in transmittance at around 345 nm which was more profound for the Ar-deposited films and particularly for the oxidized films. Zinc nitride has been found to be a wide band gap material which makes it a potential candidate for transparent optoelectronic devices. (c) 2007 Elsevier B.V All rights reserved.