Effect of Thermal Annealing up to 200°C on SnO Thin Films Deposited at Room Temperature by Direct Current Magnetron Sputtering

The effect of thermal annealing at low temperature (≤200°C) on some structural, optical, and electrical properties of tin (Sn) layers, deposited at room temperature by direct current magnetron sputtering in an argon and oxygen reactive plasma, was studied to obtain tin monoxide (SnO). The Sn layers were 70±5 nm thick. The oxygen partial pressure (OPP) was fixed at 7% or 9%. Subsequently, deposited films were thermally annealed (TA) for 1 hour at temperatures between 160° C and 200° C in air environment. X-ray diffraction patterns of films deposited at 7% and 9% of OPP showed a dominant Sn phase oriented to different crystallographic planes. Once the deposited films were annealed at 200° C, a phase of polycrystalline SnO became predominant for the deposition process at 9% of OPP. The optical bandgap energy, the refractive index and the extinction coefficient of the annealed layers varied with the TA temperature. Finally, four-point-probe measurements showed the resistivity variation of the films from as-deposited to thermally annealed up to 200° C.