Sputtering and Evaporating of High Density (111)-textured Ag Nanotwinned Films on Sapphire Wafers

- The excellent properties of nanotwinned structures have been a hot area of research in recent years. Silver (Ag) has the lowest stacking fault energy (SFE) among all FCC metals, which has a strong tendency to form a twin structure. Also, sapphire substrates are ideal for use in LED applications due to high-temperature resistance, high strength, good electrical insulations, and low dielectric loss. Depositing Ag nanotwinned films on sapphire substrates can serve as a perfect candidate for die bonding in LED manufacturing. In this study, two deposition methods had been demonstrated for the fabrication of high density (111)-textured Ag nanotwinned films on sapphire wafers. Microstructural analyses show that both the sputtered and evaporated Ag grains presented a high density of twin structure. The cross-sectional EBSD analysis of the sputtered Ag nanotwinned film indicated a highly (111)-preferred orientation to 34.6% of the overall grains. Further, the sputtering process allows the production of surface roughness of the Ag nanotwinned film up to 65.1 nm. The epitaxial growth of Ag nanotwinned films with (111)-preferred orientation can be utilized by both the deposition methods.