Optimizing defect states in $(Bi_{0.3}Sb_{0.7})_{2}Te_{3}$ ternary topological insulators using indium doping

TL;DR

This paper demonstrates that indium doping in (Bi0.3Sb0.7)2Te3 topological insulators systematically modifies defect states, improving insulating properties and electronic behavior for advanced applications.

Contribution

It provides new insights into how indium doping shifts defect energy levels and suppresses impurity bands in topological insulators, enabling tailored electronic properties.

Findings

Indium doping shifts thermal activation energy by ~100 meV.

Doping suppresses shallow impurity band at 72 meV.

Increases deep defect activation energy from 292.3 to 392 meV.

Abstract

This study investigates the influence of indium doping on the defect states in (Bi0.3Sb0.7)2Te3 (BST) ternary topological insulators. Thin (10 nm) and thick (60 nm) films of pristine BST and indium-doped BST (In0.14(Bi0.3Sb0.7)1.86Te3) were synthesized using pulsed laser deposition. The electronic properties were characterized through low-frequency noise spectroscopy and temperature-dependent resistance (R-T) measurements. For the 10 nm films, R-T analysis revealed that indium doping shifts the thermal activation energy by approximately 100 meV. This doping also suppresses a shallow impurity band at 72 meV, a finding corroborated by 1/f noise measurements. In the 60 nm films, noise spectroscopy was used to probe deep defect states, where indium doping was found to increase the activation energy from 292.3 meV to 392 meV -- a consistent shift of 100 meV. These findings demonstrate that indium doping is an effective method for systematically modifying both shallow and deep defect states, enhancing the insulating properties and offering a mechanism to engineer the electronic behavior of topological insulators for advanced electronic applications where noise reduction is crucial.