Tuning of fermi level in antimony telluride thin films by low-energy Fe−-ion implantation

The influence of magnetic dopants on the transport properties of topological insulators is of great interest. In this work, studies on the impact of Fe− ion implantation on the physical and electronic properties of Sb2Te3 thin films have been done. The implantation was done with low-energy Fe− ions at three different fluences (1 × 1013, 1 × 1014, and 5 × 1014 ions/cm2). The film thickness was estimated using Rutherford backscattering spectroscopy (RBS). Magnetic force microscopy (MFM) topographic image showed the Fe− ion-induced magnetization in thin films. Overall enhancement in the electrical resistivity with increasing implantation dose was observed in the temperature-dependent transport measurements. However, the mobility of the carriers was found to decrease with increasing fluence. The Hall measurements showed that the carrier concentration initially increased with the fluence up to 1 × 1014 ions/cm2, but further increase in the fluence results in a decrease in the carrier concentration. P-type nature of the dominant charge carriers was observed for all the fluences except the highest dose where a change in the type of carriers from p-type to n-type was observed. It can be explained based on Fe− ion implantation-induced donors as well as acceptors like defects.