Tuning of physical properties through implantation mediated Cu doping in Sb2Te3 thin films

Abstract

The time-reversal symmetry-protected surface states make topological insulators an interesting candidate for the fantastic quantum phenomenon. Nowadays, 3D Topological insulators doped with magnetic elements are becoming a promising area of research in fundamental device applications. The present work aims to investigate the influence of Cu dopants via implantation on the physical properties of Sb2Te3 thin films. Thin films synthesized using the e-beam evaporation technique were implanted with Cu ions at 5 different fluences (1 × 1013, 5 × 1013, 1 × 1014, 5 × 1014, and 1 × 1015ions/cm2). X-ray Diffraction measurements reveal the rhombohedral structure of thin films with an R-3 m space group. The smaller radii of Cu ion embedded in Sb2Te3 thin films could reduce the lattice parameter ‘c’. The ion implantation induced structural strain is also observed in Raman modes as confirmed by optical studies. The Atomic Force Microscopy (AFM) measurements indicate the effect of ion implantation on the granular morphology of thin films. The increase in grain boundaries with implantation indicates the implantation induced damage to the surface. The temperature-dependent resistivity plot suggests the enhancement of the semiconducting behavior of thin films by implantation-induced defects. Our findings provide a route to have modifications in the material in a controlled way.