Optical, structural, and electrical properties of sputter-deposited SnOx thin films

This study investigated the effect of deposition parameters on the properties of tin oxide (SnOx) thin films deposited by direct current magnetron sputtering using a Sn metal target. As confirmed by optical bandgap, X-ray photoelectron spectroscopy, high-resolution X-ray diffraction and Hall effect measurements, as-grown samples deposited at 7.5 and 10% oxygen partial pressure (OPP) and post-annealed samples deposited at 5% OPP had a p-type SnO phase, whereas samples fabricated with 7.5 and 10% OPP and annealed at 400°C had a n-type SnO2 phase. Post-annealing at 400°C increases the bandgap and injects more oxygen into the SnOx thin film, further oxidizing the sample. In addition, post-annealing greatly increased the carrier concentration of the SnOx thin film, which increased carrier scattering and, in turn, greatly reduced the mobility of the sample. The SnOx thin film deposited at 7.5% OPP and not heat treated showed the best p-type properties, with a Hall mobility of 5.11 cm2/Vs, a hole carrier concentration of 1.13 × 1015 cm−3, and a resistivity of 1082 Ωcm.