Charge puddles in a completely compensated topological insulator

TL;DR

This study investigates how charge puddles formed by bulk carriers influence electrical transport in compensated topological insulators, using electron irradiation to fine-tune compensation in Bi2Te3.

Contribution

It demonstrates that charge puddles are essential for understanding transport properties in compensated TIs, highlighting the role of bulk carrier inhomogeneities.

Findings

Charge puddles coexist with electrons and holes at optimal compensation.

Bulk carriers form charge puddles affecting electrical transport.

Charge puddles are crucial regardless of compensation method.

Abstract

Compensation of intrinsic charges is widely used to reduce the bulk conductivity of 3D topological insulators (TIs). Here we use low temperature electron irradiation-induced defects paired with in-situ electrical transport measurements to fine-tune the degree of compensation in Bi2Te3. The coexistence of electrons and holes at the point of optimal compensation can only be explained by bulk carriers forming charge puddles. These need to be considered to understand the electric transport in compensated TI samples, irrespective of the method of compensation.