Tuning of charge carrier density by deposition pressure in Sb-doped Bi2Se3 thin films

Superconducting properties of Nb, NbN, and MoN thin films grown on topological insulator Bi1.95Sb0.05Se3: a comparative study

“…A high bulk carrier density would completely mask the topological surface conduction. The deposition parameters of BSS films used in this study (350 o C, 5×10 -1 mbar Ar) yield films with smaller carrier density (∼10 19 cm -3 ) and long coherence length (∼220 nm) with a solely electron-electron dephasing mechanism [18]. However, these films are granular and a significant fraction of the grains are not oriented along the c-axis, as shown in previous studies [18,19].…”

“…Previous studies on such heterostructures have reported growth of Bi 2 Se 3 under vacuum at high temperatures [11], which would inevitably dope the system with large Se vacancy concentration and pin the Fermi level deep into the conduction band, thus obscuring the topological surface states which are expected to support the Majorana modes when superconductivity is induced. As has been reported elsewhere [18,19], Sb-doped Bi 2 Se 3 thin films with the nominal stoichiometry Bi 1.95 Sb 0.05 Se 3 (BSS) grown in high pressure argon (Ar) environments possess a smaller defect-induced charge density concentration. In this work magnetron sputtering and pulsed laser deposition (PLD) techniques have been employed for the fabrication of superconductor-TI heterostructures and the superconducting properties have been studied.…”

“…Superconductor-BSS heterostructures with less roughness can be fabricated by modifying the PLD deposition parameters of BSS. Deposition at higher substrate temperatures (∼400 o C) and low background pressures (<10 -2 mbar Ar) [18] can yield BSS films which are well oriented along the c-axis and possess larger grains, as shown in figure 6 (h). However, the carrier density is found to be high (>10 21 cm -3 ) due to large Se escape.…”

The effect of charged particle irradiation on the transport properties of bismuth chalcogenide topological insulators: a brief review

“…Two different decay exponents in different temperature ranges are observed in the as-deposited film and are successfully transformed into a single decay behaviour in the measured temperature range after the irradiation-annealing process. More importantly, the study compares the magnetotransport behaviour of PLD-grown Sb–Bi 2 Se 3 thin films 105 with Bi 2 Se 3 systems, in which Sb is included through ion irradiation. It is interesting to note that the two systems exhibit similar transport behaviour.…”

Current redistribution model of anomalous resistance behaviour in superconductor-topological insulator heterostructures

“…Superconductor-TI heterostructures fabricated in the step geometry have been studied in this work. Bi 1.95 Sb 0.05 Se 3 (BSS) TI thin films [30][31][32] of lateral dimensions 10 mm × 4 mm and of thickness 100 nm were masked using aluminium (Al) shadow mask such that half of the surface is exposed for deposition of NbN superconductor of 100 nm thickness [32]. See supplementary (suppl.)…”