Effect of gallium doping on structural and transport properties of the topological insulator Bi2Se3 grown by molecular beam epitaxy

Abstract

Topological insulators possess a non-conductive bulk and present surface states, henceforth, they are electrically conductive along their boundaries. Bismuth selenide ($B{i}_{2}S{e}_3$) is one of the most promising topological insulators. However, a major drawback is its n-type nature arising from its natural doping, which makes the transport in the bulk dominant. This effect can be overcome by shifting the chemical potential into the bandgap, turning the transport of the surface states to be more pronounced than the bulk counterpart. In this work, $B{i}_{2}S{e}_3$ was grown by molecular beam epitaxy and doped with 0.8, 2, 7, and 14 at. % of Ga, with the aim of shifting the chemical potential into the bandgap. The structural, morphological, and electronic properties of the Ga doped $B{i}_{2}S{e}_3$ are studied. Raman and X-ray diffraction measurements confirmed the incorporation of the dopants into the crystal structure. Transport and magnetoresistance measurements in the temperature range of 1.5 to 300 K show that Ga-doped $B{i}_{2}S{e}_3$ is n-type with a bulk charge carrier concentration of $10^{19}c{m}^{-3}$. Remarkably, magnetotransport of the weak antilocalization effect (WAL) measurements confirm the existence of surface states up to a doping percentage of 2 at. % of Ga and coherence length values between 50-800 nm, which envisages the possibility of topological superconductivity in this material.

arXiv comment17 pages, 8 figures, Supplementary Information included

References in corpus (17)

• Superconductivity in CuxBi2Se3 and its implications for pairing in the undoped topological insulator
• Weak localisation magnetoresistance and valley symmetry in graphene
• Superconductivity with topological surface state in SrxBi2Se3
• Tunable Surface Conductivity in Bi2Se3 Revealed in Diffusive Electron Transport
• Topological-Metal to Band-Insulator Transition in (Bi1-xInx)2Se3 Thin Films
• Weak Localization and Antilocalization in Topological Insulator Thin Films with Coherent Bulk-Surface Coupling
• Linear magnetoresistance in topological insulators: Quantum phase coherence effects at high temperatures
• Molecular beam epitaxy of high structural quality Bi2Se3 on lattice matched InP(111) substrates
• Evidence of surface transport and weak anti-localization in single crystal of Bi2Te2Se topological insulator
• Resonant levels, vacancies and doping in Bi2Te3, Bi2Te2Se and Bi2Se3 tetradymites
• Electronic structure of a superconducting topological insulator Sr-doped Bi2Se3
• Revealing surface states in In-doped SnTe superconducting nanoplates with low bulk mobility
• A combined method for synthesis of superconducting Cu doped Bi2Se3
• Structurally and Chemically Compatible BiInSe3 Substrate for Topological Insulator Thin Films
• Enhanced coherence and decoupled surface states in topological insulators through structural disorder
• Possible Lattice and Charge Order in CuxBi2Te2Se
• Introduction of Sr into Bi2Se3 thin films by molecular beam epitaxy