Phase Separation of Dirac Electrons in Topological Insulators at the Spatial Limit

Abstract

In this work we present unique signatures manifested by the local electronic properties of the topological surface state in BiTe nanostructures as the spatial limit is approached. We concentrate on the pure nanoscale limit (nanoplatelets) with spatial electronic resolution down to 1 nm. The highlights include strong dependencies on nanoplatelet size: (1) observation of a phase separation of Dirac electrons whose length scale decreases as the spatial limit is approached, and (2) the evolution from heavily n-type to lightly n-type surface doping as nanoplatelet thickness increases. Our results show a new approach to tune the Dirac point together with reduction of electronic disorder in topological insulator (TI) nanostructured systems. We expect our work will provide a new route for application of these nanostructured Dirac systems in electronic devices.

2D Layered Material‐Based van der Waals Heterostructures for Optoelectronics

“…However, the research of graphene has been severely hampered due to the absence of a bandgap, which results in a small current on/off ratio for graphene transistors . Thus, other 2D layered materials (2DLMs) with varying bandgaps including semimetals (such as WTe 2 ), topological insulators (such as Pb 1− x Sn x Te, Bi 2 Te 3 ), semiconductors (such as black phosphorous (BP), MoS 2 , WS 2 , WSe 2 ), insulators (such as boron nitride (BN)). Different from gapless graphene, these 2DLMs possess bandgaps in a wide range and can also be modulated with the changing thickness, which have triggered tremendous interest in many fields such as field effect transistors, photodetectors, flexible devices …”

The role of morphology on the emergence of topologically trivial surface states and selection rules in topological-insulator nano-particles

“…Important examples for their relatively large band-gap [10,11] are the metal dichalcogenides Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 , displaying an anisotropic crystal structure composed by stacked quintuple layers (five covalentlybonded atomic layers) stabilized by van der Waals [12] interactions. With the aid of nanofabrication techniques such as vapor-phase growth [13][14][15][16], solution-phase growth [17][18][19], mechanical [20][21][22] and chemical [23] exfoliation, these materials allow for the synthesis of TI nanostructures at different sizes and morphologies [15][16][17][24][25][26][27], including nanoribbons [13,22,26], nanowires [14], nanorods [19,25] and nanoplates [15-17, 24, 27] of variable thickness with sharp edges and corners.…”

Nanoimaging of Electronic Heterogeneity in Bi2Se3 and Sb2Te3 Nanocrystals

“…[9,[19][20][21] However, STM is limited to conducting substrates and typically cannot access heterogeneity that spans the multiple atomic-to-mesoscopic length scales. Infrared scatteringtype scanning near-field optical microscopy (IR s-SNOM), in contrast, based on an atomic force microscope (AFM) coupled with a tip-localized optical excitation, can probe the low-energy local electronic structure associated with the Drude response with 10 nm resolution, and over multiple length scales with exquisite sensitivity.…”

“…Scanning tunneling microscopy (STM) has been used to identify the individual vacancies and dopants at the atomic scale . However, STM is limited to conducting substrates and typically cannot access heterogeneity that spans the multiple atomic‐to‐mesoscopic length scales.…”