Improvement in micro-structural and mechanical properties of zinc film by surface treatment with low temperature argon plasma

Nanocrystalline zinc films were deposited on gold coated borosilicate glass substrates by thermal evaporation method using zinc powders as the source material and then treated with argon plasma at various temperatures. From X-ray diffraction study, the as-deposited films are found to be metallic Zn and polycrystalline in nature. The crystalline nature improves with the increase of temperature up to 200 °C and decreases with the further increase of temperature to 300 °C. The binding energy observed for Zn 2p3/2, and the binding energy separation between Zn 2p3/2 and Zn 2p1/2 in the X-ray photoelectron spectrum indicate that the films are metallic zinc films. Transmission electron microscopic study shows hexagonal shaped grains having size ∼58 nm upon treatment with Ar plasma. It is clearly shown the grain growth and distinct grain boundary with the increase in temperature. The average Young's modulus (E) and hardness (H) are measured to be 84 GPa and 4.0 GPa for as-deposited film, whereas 98 GPa and 5.8 GPa for plasma treated film at 200 °C. The enhancement in mechanical properties is attributed to improvement in crystalline nature of the film and better interlinking between grains and boundaries.

Highlights► Deposition of Zinc thin film on gold coated borosilicate glass by rf plasma treatment. ► Improvement of crystalline ordering in rf plasma treated films at 200 °C. ► Distinct grain growth and grain boundary with the increase in temperature. ► Improvement of the mechanical properties like hardness and Young's modulus.