Atomically Abrupt Topological p-n Junction

TL;DR

This paper demonstrates a novel method to create atomically abrupt topological p-n junctions by growing ultrathin Sb films on Bi2Se3, enabling scalable, nanoscale electronic and spintronic devices based on topological surface states.

Contribution

It introduces an innovative fabrication technique for lateral topological p-n junctions with atomic precision using hybridization of surface states.

Findings

Achieved a 2 nm lateral topological p-n junction.

Demonstrated hybridization-induced p-type TSS on Bi2Se3 surface.

Enabled scalable topological device architectures.

Abstract

Topological insulators (TI's) are a new class of quantum matter with extraordinary surface electronic states, which bear great potential for spintronics and error-tolerant quantum computing. In order to put a TI into any practical use, these materials need to be fabricated into devices whose basic units are often p-n junctions. Unique electronic properties of a 'topological' p-n junction were proposed theoretically such as the junction electronic state and the spin rectification. However, the fabrication of a lateral topological p-n junction has been challenging because of materials, process, and fundamental reasons. Here, we demonstrate an innovative approach to realize a p-n junction of topological surface states (TSS's) of a three-dimensional (3D) topological insulator (TI) with an atomically abrupt interface. When a ultrathin Sb film is grown on a 3D TI of Bi2Se3 with a typical n-type TSS, the surface develops a strongly p-type TSS through the substantial hybridization between the 2D Sb film and the Bi2Se3 surface. Thus, the Bi2Se3 surface covered partially with Sb films bifurcates into areas of n- and p-type TSS's as separated by atomic step edges with a lateral electronic junction of as short as 2 nm. This approach opens a different avenue toward various electronic and spintronic devices based on well defined topological p-n junctions with the scalability down to atomic dimensions