Thin copper oxide films prepared by ion beam sputtering with subsequent thermal oxidation: Application in chemiresistors

摘要

Copper oxide films were prepared by thermal oxidation of thin Cu films deposited on substrates by ion beam sputtering. The subsequent oxidation was achieved in the temperature range of 200 degrees C-600 degrees C with time of treatment from 1 to 7 h (with a 1-h step) in a furnace open to air. At temperatures 250 degrees C-600 degrees C, the dominant phase formed was CuO, while at 200 degrees C mainly the Cu2O phase was identified. However, the oxidation at 200 degrees C led to a more complicated composition - in the depth Cu2O phase was observed, though in the near-surface layer the CuO dominant phase was found with a significant presence of Cu(OH)(2). A limited amount of Cu2O was also found in samples annealed at 600 degrees C. The sheet resistance R-S of the as-deposited Cu sample was 2.22 Omega/square, after gradual annealing R-S was measured in the range 2.64 MS Omega/square-2.45G Omega/square. The highest Rs values were obtained after annealing at 300 degrees C and 350 degrees C, respectively. Oxygen depth distribution was studied using the O-16(alpha,alpha) nuclear reaction with the resonance at energy 3032 keV. It was confirmed that the higher oxidation degree of copper is located in the near-surface region.