Band bending at interfaces between topological insulator Bi2Se3 and transition metals

TL;DR

This study investigates the electronic and chemical properties of interfaces between topological insulator Bi2Se3 and transition metals, revealing band bending effects that impact potential spintronic device applications.

Contribution

It demonstrates that clean, chemically stable interfaces can be formed with ultrathin transition metal layers and uncovers significant band bending phenomena near the interface.

Findings

Achieved chemically clean interfaces with 1 nm metal layers

Observed depletion or inversion of charge carriers near the interface

Detected strong band bending affecting surface state properties

Abstract

Interfaces between exfoliated topological insulator Bi2Se3 and several transition metals deposited by sputtering were studied by XPS, SIMS, UPS and contact I-V measurements. Chemically clean interfaces can be achieved when coating Bi2Se3 with a transition metal layer as thin as 1 nm, even without capping. Most interestingly, UPS spectra suggest depletion or inversion in the originally n-type topological insulator near the interface. Strong band bending in the topological insulator requires careful material engineering or electric biasing if one desires to make use of the spin locking in surface states in the bulk gap for potential spintronic applications