Growth of topological insulator Bi2Se3 particles on GaAs via droplet epitaxy

Abstract

The discovery of topological insulators (TIs) and their unique electronic properties has motivated research into a variety of applications, including quantum computing. It has been proposed that TI surface states will be energetically discretized in a quantum dot nanoparticle. These discretized states could then be used as basis states for a qubit that is more resistant to decoherence. In this work, prototypical TI Bi2Se3 nanoparticles are grown on GaAs (001) using the droplet epitaxy technique, and we demonstrate the control of nanoparticle height, area, and density by changing the duration of bismuth deposition and substrate temperature. Within the growth window studied, nanoparticles ranged from 5 to 15 nm in height with an 8–18 nm equivalent circular radius, and the density could be relatively well controlled by changing the substrate temperature and bismuth deposition time.

Optimization of the Growth of the Van der Waals Materials Bi2Se3 and (Bi0.5In0.5)2Se3 by Molecular Beam Epitaxy

“…To preserve and to take full advantage of the surface states, researchers have explored various ways to obtain crystalline thin films, ranging from top-down methods like mechanical exfoliation − to bottom-up methods like epitaxial growth via molecular beam epitaxy (MBE), − physical vapor deposition (PVD), chemical vapor deposition (CVD), , etc. MBE is often used for chalcogenide-based TI growth because it produces high-purity films, enables the precise control of the growth parameters including the film thickness and doping level, and can be used to create atomically sharp interfaces in TI-based heterostructures. − MBE can also be used to synthesize pristine topological insulator nanoparticles. , Unfortunately, applications of the Bi 2 Se 3 surface states have been limited by the poor film quality: intrinsic point defects (such as selenium vacancies or metal/chalcogenide antisite defects) may introduce unwanted doping, causing the Fermi level to be pinned in the conduction band, which will obscure the signals from the surface states; and twin domains (also called antiphase domains) often form due to the threefold crystal symmetry, introducing dislocations in the film that serve as extra scattering paths for the surface states, thus limiting the surface state electron mobility . A variety of MBE-based techniques have been used to reduce the doping and to improve the film crystallinity. , In this paper, we will do a head-to-head comparison of several growth strategies that have previously been tried on TIs, transition metal dichalcogenides, or III-V semiconductors.…”

“…18−20 MBE can also be used to synthesize pristine topological insulator nanoparticles. 21,22 Unfortunately, applications of the Bi 2 Se 3 surface states have been limited by the poor film quality: intrinsic point defects (such as selenium vacancies or metal/ chalcogenide antisite defects) may introduce unwanted doping, causing the Fermi level to be pinned in the conduction band, which will obscure the signals from the surface states; 12 and twin domains (also called antiphase domains) often form due to the threefold crystal symmetry, introducing dislocations in the film that serve as extra scattering paths for the surface states, thus limiting the surface state electron mobility. 23 A variety of MBE-based techniques have been used to reduce the doping and to improve the film crystallinity.…”