A study on phase transformation of SnOx thin films prepared by reactive magnetron sputtering

In the paper, SnOx thin films were deposited by reactive magnetron sputtering from a tin target in O2 containing working gas. The evolution from Sn-containing SnO to tetravalent SnO2 films was investigated. The films could be classified into three groups according to their optical band gaps, which are Eg<2.5 eV, Eg=3.0–3.3 eV and Eg>3.7 eV. The electric measurements show that high conductivity can be obtained much easier in SnO2 than in SnO films. A high electron mobility of 15.7 cm2 V−1 s−1, a carrier concentration of 1.43×1020 cm−3 and a resistivity of 2.8×10−3 Ω cm have been achieved in amorphous SnO2 films. Films with the optical band gap of 3.0–3.3 eV remain amorphous though the substrate temperature is as high as 300 °C, which implies that °btaining high mobility in p-type SnO is more challenging in contrast to n-type SnO2 films.