Topological p-n Junction

TL;DR

This paper explores the creation of a topological p-n junction on an ideal topological insulator, highlighting the emergence of chiral edge states and proposing a practical realization in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ for device applications.

Contribution

It introduces a method to realize topological p-n junctions with controllable surface states and predicts the existence of chiral edge states under magnetic fields.

Findings

Chiral edge states appear along the junction interface.

Proposed realization in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ with tunable surface states.

Potential for device applications using topological p-n junctions.

Abstract

We consider a junction between surface $p$-type and surface $n$-type on an ideal topological insulator in which carrier type and density in two adjacent regions are locally controlled by composition graded doping or electrical gating. Such junction setting on topological insulators are fundamental for possible device application. A single gapless chiral edge state localized along the junction interface appears in the presence of an external magnetic field, and it can be probed by scanning tunneling microscopy and transport measurements. We propose to realize this topological \emph{p-n} junction in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$, which has insulating bulk properties and a tunable surface state across the Dirac cone.