Effect of the addition of zirconium on the electrical, optical, and mechanical properties and microstructure of ITO thin films

Indium Tin Oxide (ITO) thin films are doped with zirconium (Zr) by varying the direct current (DC) power sources to investigate the effects of Zr doping on surface morphology, microstructure, and mechanical, electrical, and optical properties. The ITO:Zr specimens possess more grains with the (400) orientation when the DC power is elevated. Crystallinity and surface roughness are highly dependent on grain size. The product value of crystallinity and grain size is observed to be positively correlated to the surface roughness. Reduced modulus and hardness of specimen are lowered by increasing the DC power, and these two parameters are also positively correlated to the product of crystallinity and grain size. In this study, the choice of 35 W as the power can bring in the highest transmittance (>81%) in the wavelength region of 380–2600 nm and the lowest resistivity of all specimens. Increasing the power to be higher than 35 W will produce more excessive carriers to reduce the carrier concentration and mobility, thus elevating the resistivity. A significant rise in the infrared transmittance (800–2600 nm) compared to the undoped ITO thin film is achieved by doping the Zr into ITO with a DC power of 35 W.