Controlled MOCVD growth of Bi2Se3 topological insulator nanoribbons

TL;DR

This paper presents a new MOCVD method for synthesizing Bi2Se3 topological insulator nanoribbons with controlled morphology and stoichiometry, enabling better surface state studies for electronic applications.

Contribution

It introduces a controlled MOCVD growth process for Bi2Se3 nanostructures, demonstrating tunable morphology and growth mechanisms based on reaction conditions.

Findings

MOCVD allows control of Se/Bi flux ratio during growth.

Nanoribbons are nucleated by gold nanoparticles at the base.

Growth conditions determine whether ribbons or platelets are formed.

Abstract

Topological insulators are a new class of materials that support topologically protected electronic surface states. Potential applications of the surface states in low dissipation electronic devices have motivated efforts to create nanoscale samples with large surface-to-volume ratios and highly controlled stoichiometry. Se vacancies in Bi2Se3 give rise to bulk conduction, which masks the transport properties of the surface states. We have therefore developed a new route for the synthesis of topological insulator nanostructures using metalorganic chemical vapour deposition (MOCVD). MOCVD allows for control of the Se/Bi flux ratio during growth. With the aim of rational growth, we vary the Se/Bi flux ratio, growth time, and substrate temperature, and observe morphological changes which indicate a growth regime in which nanoribbon formation is limited by the Bi precursor mass-flow. MOCVD growth of Bi2Se3 nanostructures occurs via a distinct growth mechanism that is nucleated by gold nanoparticles at the base of the nanowire. By tuning the reaction conditions, we obtain either single-crystalline ribbons up to 10 microns long or thin micron-sized platelets.