Ion bombardment-induced enhancement of the properties of indium tin oxide films prepared by plasma-assisted reactive magnetron sputtering

Research on tin doped indium oxide (ITO) has for many years been stimulated by the need to simultaneously optimize the electrical, optical and mechanical properties, and by new challenges related to the deposition of transparent conducting oxides on flexible plastic substrates. In the present work, we investigate the growth and optical, electrical, and mechanical (hardness, elastic modulus and stress) properties of ITO films deposited by plasma assisted reactive magnetron sputtering (PARMS) from an indium-tin alloy target. PARMS achieves an effective control of bombardment by reactive species (e.g., O2+, O+) on the surface of the growing film by varying the bias voltage, VB, induced by a radiofrequency power applied to the substrate. Stress-free films possessing high transparency (> 80% - film on glass) and low resistivity (4 × 10− 4 Ω cm) can be deposited by PARMS under conditions of intense ion bombardment (≤ 600 eV).