Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin (original) (raw)
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Stanene: Atomically Thick Free- standing Layer of 2D Hexagonal Tin OPEN
Scientific Reports, 2016
Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar 'd' spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets. Two dimensional (2D) layered materials have recently gained renewed interest due to their exotic electronic properties along with high specific surface area. The prospects of exploiting these properties in sensing, catalysis, energy storage, protective coatings and electrochromism have witnessed a paradigm shift towards the exploration of these sophisticated 2D materials. The exemplary performance of graphene 1 which is among the first of these elemental 2D materials have initiated a runaway effect in the pursuit of studying alternative 2D materials. Even though graphene has tunable exotic electronic properties 2 , the spin-orbit (SO) coupling is weak 3-5 limiting its applications as spin filters, topological insulators etc. Topological insulators by their very nature force the electrons to travel on the surface at very high speeds thereby finding useful applications in electronic and photonic devices. Exploration of group IV elements using first principles calculations have revealed that the SO coupling increases as the atomic weight of the basis atoms in the honeycomb lattice 6,7. Tin is one of the heaviest elements in this series having strong spin-orbit coupling making it a promising applicant for room temperature topological insulator 8. Thus there is an urgent need to discover novel 2D materials in the post graphene age to overcome its deficiencies. Here we report the synthesis of few-layer stanene (FLS) using ultra-fast laser-material interactions. FLS is analogous to few-layer graphene and can be visualized by replacing carbon atoms by tin on a graphene lattice. Structural characterization performed using high resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray analysis (EDAX) and selected area electron diffraction (SAED) detectors confirm the presence of hexagonal lattice of Sn atoms. EDAX and comparative Raman studies that oxide phases are absent and rules out the possibility of (111) α-Sn sheets. Height profile measured using atomic force micros-copy (AFM) suggests interlayer separation of ~3.3 Å and in good agreement with that of recently reported epitax-ial stanene. Further the UV-Vis spectrum and Raman spectrum are in good agreement with the optical spectra and phonon frequencies calculated using first principles techniques. The structural characterization along with optical signature suggests the synthesis of free standing stanene sheets. Results and Discussions Free standing stanene sheets were synthesized by impinging pulses from a tunable Ti:Saphire ultra-fast femto second laser (140 femto-second pulse width and 80 MHz repetition rate) on to a target in liquid medium. This interaction of femo-second laser pulse due to inverse Bremsstrahlung multiphoton absorption process 9 induce non-equilibrium conditions 10. This we hypothesize initiates the change of phase from tetragonal structure of
A Perspective on Recent Advances in 2D Stanene Nanosheets
Advanced Materials Interfaces, 2019
Advancements in 2D nanomaterials have been impacting a wide range of technology‐driven applications. Here, the authors highlight stanene, a material that comprises a monolayer of elemental tin atoms, as a new addition to the monoelemental 2D family. Recent successes in the experimental realization of stanene in supported heterostructures and in free‐standing form have expanded interest in exploring and unlocking its potential applications, as predicted from advanced theoretical calculations. Stanene exhibits several remarkable features, including a large spin–orbit gap (allowing room‐temperature electronics based on the quantum spin Hall effect), topological superconductivity, quantum anomalous Hall behavior, giant magnetoresistance, and efficient thermoelectricity. Research into stanene and stanene‐based 2D materials, both experimentally and theoretically, is suggesting immense potential for future quantum‐based electronics systems. Here, the fundamental features of stanene, progre...
Optical Properties of Stanene-like Nanosheets on Al2O3(0001): Implications for Xene Photonics
ACS applied nano materials, 2021
Stanene is one of the most intriguing two-dimensional (2D) materials because of its nontrivial topological properties. Here, the optical properties from THz to UV of molecular beam deposited tin nanosheets on Al 2 O 3 (0001) are reported. The experimental absorption coefficient cannot be described in terms of metallic tin or tin oxides. Nonetheless, a similar optical behavior was predicted by theory for freestanding stanene, thus suggesting the formation of the 2D tin nanosheets with stanene-like properties. These findings show that 2D tin bears appealing optical properties in a broad range of the electromagnetic spectrum, thus paving the way to Xenes-based nanophotonics.
Optical Properties of Stanene-like Nanosheets on Al2O3(0001): Implications for Xene Photonics
ACS Applied Nano Materials
Stanene is one of the most intriguing two-dimensional (2D) materials because of its nontrivial topological properties. Here, the optical properties from THz to UV of molecular beam deposited tin nanosheets on Al 2 O 3 (0001) are reported. The experimental absorption coefficient cannot be described in terms of metallic tin or tin oxides. Nonetheless, a similar optical behavior was predicted by theory for freestanding stanene, thus suggesting the formation of the 2D tin nanosheets with stanene-like properties. These findings show that 2D tin bears appealing optical properties in a broad range of the electromagnetic spectrum, thus paving the way to Xenes-based nanophotonics.
Structure determination of ultra-flat stanene on Cu(111) using low energy electron diffraction
Surface Science, 2019
The 2D hexagonal structure of tin atoms which is termed stanene is structurally determined on a Cu(111) substrate using low energy electron diffraction (LEED). The structural analysis of Cu{111}-p(2 × 2)-Sn at a coverage of 0.5 at low temperature reveals the relaxation of underlying Cu atoms, which stabilizes the formation of almost zero-buckled Sn atoms forming a honeycomb structure. Our results using quantitative LEED conclusively reveals an ultra-flat stanene structure that complements well with the previous calculations. The detailed structural analysis presented in this article is expected to give in-depth information for characterizing the properties of as-grown stanene.
Stanene the New Gas Sensing Wonder Material: Current Status and Future Prospects
2021
In the search for new 2D materials beyond graphene with similar exemplary properties Stanene the new graphene relative was successfully synthesized and characterized in 2016 [14]. This new material which consists of atomically thin tin (Sn) atoms arranged in a hexagonal lattice has shown great promise in gas sensing applications in its pristine, doped and functionalized forms as evidenced by the recent research outputs following its discovery. Researchers have discovered that with its exotic properties it is highly efficient in the detection of the environmentally harmful gases like SO2, NO2, CO2, NH3 and can serve as a multifunctional gas sensor. In this focused and up-to-date review we aim to group the literature on first principles studies of stanene regards to its application for gas sensing and critically examine the success/failures of its multifunctional gas sensing properties as compared to graphene. We systematically present and discusses how structural deformations, defect...
Structure and binding of stanene on the Al$_{2}$O$_{3}$(0001) surface
arXiv: Materials Science, 2020
Stanene, the two-dimensional monolayer form of tin, has been predicted to be a 2D topological insulator due to its large spin-orbit interaction. However, a clear experimental demonstration of stanene's topological properties has eluded observation, in part because of the difficulty of choosing a substrate on which stanene will remain topologically nontrivial. In this paper, we present first-principles density functional theory (DFT) calculations of epitaxial monolayer stanene grown on the (0001) surface of alumina, Al$_{2}$O$_{3}$. We perform a detailed analysis of the binding energy and electronic structure of stanene on Al$_{2}$O$_{3}$, and demonstrate that it is a quantum spin Hall insulator. In addition, we discuss the relevance of decorated stanene and dumbbell stanene on the alumina surface.
Structural, Electronic and Optical Properties of Stanene Doped Beryllium: A First Principle Study
Physical Science International Journal, 2021
Stanene is a 2D hexagonal layer of tin with exceptional electronic and optical properties. However, the semiconductor applications of stanene are limited due to its zero band-gap. However, doping stanene could lead to a band gap opening, which could be a promising material for electronic and optical applications. In this work, optimized structure, electronic band structure, real and imaginary parts of the frequency-dependent dielectric function, electron loss function, and refractive index of stanene substitutionally doped with alkaline earth metal (beryllium) were analyzed using density functional theory (DFT) calculations as implemented in the quantum espresso and yambo suites. A pure stanene has a zero band gap energy, but with the inclusion of spin-orbit coupling in the electronic calculation of pure stanene, the band-gap is observed to open up by 0.1eV. Doping stanene with beryllium opens the band-gap and shifts the Dirac cone from the Fermi level, the band gap opens by 0.25eV,...
Semimetal behavior of bilayer stanene
Physica E: Low-dimensional Systems and Nanostructures, 2017
Stanene is a two-dimensional (2D) buckled honeycomb structure which has been studied recently owing to its promising electronic properties for potential electronic and spintronic applications in nanodevices. In this article we present a first-principles study of electronic properties of fluorinated bilayer stanene. The effect of tensile strain, intrinsic spin-orbit and van der Waals interactions are considered within the framework of density functional theory. The electronic band structure shows a very small overlap between valence and conduction bands at the Γ point which is a characteristic of semimetal in fluorinated bilayer stanene. A relatively high value of tensile strain is needed to open an energy band gap in the electronic band structure and the parity analysis reveals that the strained nanostructure is a trivial insulator. According to our results, despite the monolayer fluorinated stanene, the bilayer one is not an appropriate candidate for topological insulator.
Computational Condensed Matter
The recent work on stanene as quantum spin Hall insulators made us investigate bilayer stanene using first principle calculations. With an aim of improving and developing new properties, via modulating the stacking order (and angle) of the bilayers. This stacking of layers has been proven technique for modulating the properties of monolayer materials. Here we design multiple bilayer systems, with different stacking angles and AA and AB configurations. Rather observing an improvement in bandgap due to spin-orbit coupling (SOC), we witness a splitting of the band due to SOC, a characteristic behavior of stacked MoS2 sheets. This splitting of the bands gives rise to different, independent and distinct spin-up and spin-down channels, manifesting a valley dependent spin polarization. Also, as a contrast to stacked MoS2 system we notice in our system the stacking angle and order, does effect electronic states.