Bulk Fermi surface and electronic properties of Cu$_{0.07}$Bi$_{2}$Se$_{3}$

TL;DR

This study investigates the bulk electronic structure of Cu-doped Bi2Se3, revealing a three-dimensional Fermi surface, increased impurity bands, and structural changes due to Cu incorporation, using multiple experimental techniques.

Contribution

It provides detailed insights into the bulk electronic properties and impurity effects of Cu-doped Bi2Se3, highlighting the role of Cu in modifying the material's electronic and structural characteristics.

Findings

Bulk 3D Fermi surface with anisotropy approximately 2

Increase in impurity bands and microstrain due to Cu doping

Effective mass similar to undoped Bi2Se3

Abstract

The electronic properties of Cu$_{0.07}$Bi$_{2}$Se$_{3}$ have been investigated using Shubnikov-de Haas and optical reflectance measurements. Quantum oscillations reveal a bulk, three-dimensional Fermi surface with anisotropy $k^{c}_{F}/k^{ab}_{F}\approx$ 2 and a modest increase in free-carrier concentration and in scattering rate with respect to the undoped Bi$_{2}$Se$_{3}$, also confirmed by reflectivity data. The effective mass is almost identical to that of Bi$_{2}$Se$_{3}$. Optical conductivity reveals a strong enhancement of the bound impurity bands with Cu addition, suggesting that a significant number of Cu atoms enter the interstitial sites between Bi and Se layers or may even substitute for Bi. This conclusion is also supported by X-ray diffraction measurements, where a significant increase of microstrain was found in Cu$_{0.07}$Bi$_{2}$Se$_{3}$, compared to Bi$_{2}$Se$_{3}$.