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(a) Ball-and-stick model of the rhombohedral Bi2Se3 or Sb2Se3 crystals. Bismuth or antimony atoms are shown by purple balls, selenium atoms by yellow balls. (b) RHEED patterns from to the initial Bi2Se3 film of 24 QL thickness grown on Si(1 1 1) and Sb2Se3 2 QL and 5 QL-thick films grown atop of it. ((c) and (d)) STM images (400 × 400 nm², Vs=−0.8 V) of 2 and 5 QL-thick films of Sb2Se3 grown on Bi2Se3. (e) STM profiles along the hexagonal Moiré directions. Profiles are separated by 0.15 nm in height for clarity. (f) FFT image taken from (d) together with profile along line marked by red arrows. Profile is fitted by Lorentzians. Red peak corresponds to low frequency background while blue peaks correspond to Moiré lattice.
Source publication
Thin films of rhombohedral Sb2Se3 with thicknesses from 1 to 5 quintuple layers (QL) were grown on Bi2Se3/Si(111) substrate. The electronic band structure of the grown films and the Sb2Se3/Bi2Se3 interface were studied using angle-resolved photoemission spectroscopy. It was found that while Sb2Se3 has an electronic band structure generally similar...
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Citations
... Unfortunately, Sb 2 Se 3 always crystallizes in the orthorhombic structure at ambient conditions [34,35]. Only recently, its existence in a few-layers thin film has been shown and its structural stability at room temperature conditions fully discussed [36,37]. Therefore, the existence of a pressureinduced TQPT in β-Sb 2 Se 3 is far from being experimentally demonstrated. ...
... Due to the strong SOC and a narrow band gap, these systems are identified as secondgeneration 3D TIs, and all of them show a single Dirac cone at Γ point of the BZ [5][6][7]. In this class, it is important to include β-As 2 Te 3 [29,30] and β-Sb 2 Se 3 [19,27,33,36,39] that are NIs due to insufficient SOC strength, as previously commented. ...
... But the synthesis of single-crystal was not supported (or proven) by any systematic structural analysis such as single crystal XRD, microstructural characterization like TEM, etc. Mention must be made that the reported rhombohedral phase (R3m of Sb 2 Se 3 ) observation in bulk form has not been verified to date by any other experimental group. Only a few-layer film of this phase seems to have been recently synthesized over a Bi 2 Se 3 substrate [36]. Most of the experimental studies confirm that Sb 2 Se 3 adopts an orthorhombic structure (SG: Pnma) at room temperature conditions [34,35]. ...
Research on topological and topological crystalline insulators is one of the most intense and exciting topics due to its fascinating fundamental science and potential technological applications. Pressure (strain) is one potential pathway to induce the non-trivial topological phases in some topologically trivial (normal) insulating or semiconducting materials. In the last ten years, there have been substantial theoretical and experimental efforts from condensed-matter scientists to characterize and understand pressure-induced topological quantum phase transitions. In particular, a promising enhancement of the thermoelectric performance through pressure-induced topological quantum phase transition has been recently realized; thus evidencing the importance of this subject in society. Since the pressure effect can be mimicked by chemical doping or substitution in many cases, these results have opened a new route to develop more efficient materials for harvesting green energy at ambient conditions. Therefore, a detailed understanding of the mechanism of pressure-induced topological quantum phase transitions in various classes of materials with spin-orbit interaction is crucial to improve their properties for technological implementations. Hence, this review focuses on the emerging area of pressure-induced topological quantum phase transitions to provide a comprehensive understanding of this subject from both theoretical and experimental points of view. In particular, it covers the Raman signatures of detecting the topological transitions (under pressure), some of the important pressure-induced topological and topological crystalline insulators of the various classes of spin-orbit coupling materials, and provide future research directions in this interesting field.
... For the Bi cell temperature of 700 • C, the three vibrational modes were weaker than those at 750 • C, indicating the thinner film of Bi 2 Se 3 and thus the lower deposition rate. According to the previous literature [37], the growth rate of Bi 2 Se 3 film depends on the Bi deposition rate in an Se-rich atmosphere (evaporation rate: Se:Bi =~10:1). The Bi deposition rate depends on the temperature of the Bi source cell. ...
In the present study, vacuum evaporation method is used to deposit Bi2Se3 film onto Si nanowires (NWs) to form bulk heterojunction for the first time. Its photodetector is self-powered, its detection wavelength ranges from 390 nm to 1700 nm and its responsivity reaches its highest value of 84.3 mA/W at 390 nm. In comparison to other Bi2Se3/Si photodetectors previously reported, its infrared detection length is the second longest and its response speed is the third fastest. Before the fabrication of the photodetector, we optimized the growth parameter of the Bi2Se3 film and the best Bi2Se3 film with atomic steps could finally be achieved. The electrical property measurement conducted by the physical property measurement system (PPMS) showed that the grown Bi2Se3 film was n-type conductive and had unique topological insulator properties, such as a metallic state, weak anti-localization (WAL) and linear magnetic resistance (LMR). Subsequently, we fabricated Si NWs by the metal-assisted chemical etching (MACE) method. The interspace between Si NWs and the height of Si NWs could be tuned by Ag deposition and chemical etching times, respectively. Finally, Si NWs fabricated with the Ag deposition time of 60 s and the etching time of 10 min was covered by the best Bi2Se3 film to be processed for the photodetector. The primary n-Bi2Se3/p-Si NWs photodetector that we fabricated can work in a self-powered mode and it has a broadband detection range and fast response speed, which indicates that it can serve as a promising silicon-based near- and mid-infrared photodetector.
... Even simple band bending could dramatically affect conduction properties and superconductivity at the heterointerface [6,7]. Then, crystallographic configurations that are unstable in a bulk could be realized in a thin-film limit [8,9]. Finally, substrate-related surface reconstruction could be formed in a sub-unit-cell limit with completely new crystal structure, stoichiometry, etc. ...
In this paper, we report on the transient phase that forms at the initial stages of InSe growth on Si(111) surface. Using scanning tunneling microscopy and angle resolved photoemission spectroscopy observation and density-functional-theory (DFT) calculations we found that it consists of In-Se bi-layer that is half of the authentic InSe quadruple layer (QL). It has indirect band gap of ~1.2 eV and the parabolic shape of the valence band in contrast to the Mexican-hat shape of the valence band observed for InSe QL. Parity analysis of the valence bands suggests inversion of the Se pz and pxy orbitals near the Г point. We attribute the observed features of the InSe valence bands to the charge transfer from the InSe bi-layer to the Si(111) substrate.
We report a comparative theoretical study of the Pnma and R 3̄ m phases of Sb 2 S 3 , Bi 2 S 3 , and Sb 2 Se 3 close to ambient pressure and show that both phases of Sb 2 S 3 may coexist up to moderate applied pressures.
