Charge compensation by phase segregated Sb2Se3 phase in Bi1.95Sb0.05Se3 topological insulator thin films

Abstract

We report the charge compensation in Sb-doped Bi₂Se₃ thin films by the segregated Sb₂Se₃ phase. Films were deposited on Si/SiO₂ substrates via pulsed laser deposition at different laser fluences varying from 1.25 J-cm⁻² to 3.25 J-cm⁻². GI-XRD confirms the rhombohedral structure of Bi_1.95Sb_0.05Se₃ along with a secondary Sb₂Se₃ phase. The phase fraction of the Sb₂Se₃ diminishes with increasing laser fluence. The film deposited at the lower fluence exhibits a bulk-insulating behavior, with a reduction in carrier density by one order. Magnetoconductivity analysis using the Hikami–Larkin–Nagaoka equation shows that α value decreases from 5 to 0.5, and the phase coherence exponent γ varies from 0.92 to 0.37 with decreasing fluence, indicating the suppression of bulk conduction channels. STM-IV studies reveal an increase in the band gap from 0.197 eV to 0.32 eV as the phase fraction of Sb₂Se₃ increases.