Resonant impurities states-driven topological transition in quantum well

TL;DR

This paper theoretically proposes a new quantum well system where impurity-driven band anti-crossings induce topological phase transitions, offering a practical approach for topological insulators using standard semiconductor fabrication.

Contribution

The study introduces a novel method to realize topological transitions in quantum wells through impurity-induced strain and band anti-crossings, expanding the potential for topological insulators in semiconductor systems.

Findings

Negative band gap correlates with topological phase transition.

Strain tuning via nitrogen and bismuth concentrations enables control of topological states.

Theoretical model predicts feasible experimental realization.

Abstract

We demonstrate theoretically that a new system quantum well can realize the topological transition based on the 16-band kp model. Utilizing the strain introduced by the doped impurities, the band anti crossing induced by the doped nitrogen and valence band anti crossing induced by the doped bismuth, the band gap of the quantum well is rapidly decreased and even becomes negative. As a result, the topological transitions arise. Furthermore, the band gap as a function of the concentration of nitrogen and bismuth is calculated, where the negative gap corresponds to the topological phase. Noting the cancel of strain resulting from the combination of tensile strain introduced by N and strain introduced by Bi, we can easily tune the ratio of the N and Bi to meet the requirement of strain in the crystal growth procedure. Our proposal provides a promising approach for topological insulator in traditional semiconductor system utilizing the semiconductor fabrication technologies.