Comparative study of ITO layers deposited by DC and RF magnetron sputtering at room temperature

Two different magnetron sputtering techniques with RF and DC plasma discharge modes were tested for room temperature deposition of ITO layers from In2O3:SnO2 targets (10 wt% SnO2). The influence of sputtering conditions (mainly the sputtering power and oxygen content in the Ar–O2 gas mixture) on the transparency and conductivity of the formed layers was investigated. The ITO films obtained both by RF and DC magnetron sputtering at room temperature have a high transparency in the visible wavelength range (80–85%) and a low surface resistance (20–25 Ω/sq for ∼300 nm thickness) but their optimized deposition conditions and structural properties are significantly different. The DC sputtering can be performed in pure Ar with a lower discharge power density (1.0 W/cm2) and relatively high deposition rate (∼60 nm/min) while the RF sputtering requires Ar–O2 (3.0 vol.% O2) gas mixture, higher discharge power density (1.5 W/cm2) and yields a lower deposition rate (∼20 nm/min). The RF sputtered ITO layers show a crystalline structure with strong (2 2 2), (4 0 0), (4 4 0), (6 2 2) X-ray diffraction peak intensities while the DC layers are amorphous with surface morphology formed by nano-scale grains.