Phosphorene analogues: Isoelectronic two-dimensional group-IV monochalcogenides with orthorhombic structure

Gomes, Lídia C.; Carvalho, Alexandra

doi:10.1103/physrevb.92.085406

Cited by 430 publications

(396 citation statements)

References 59 publications

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“…The generic results presented here call to investigate the properties recently predicted on crystalline samples (valleytronics, shift-current photovoltaics, and piezoelectronics) [15][16][17][18] as 2D disorder sets in; something that will be pursued in forthcoming work. Having T c = 510 K, GeS monolayers appear as the proper crystalline material platform -already available in the bulk form-for the pursuit of MM-based applications that require crystallinity of the 2D lattice at room temperature.…”

Section: Resultsmentioning

confidence: 99%

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Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers

et al. 2016

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Ridged, orthorhombic two-dimensional atomic crystals with a bulk Pnma structure such as black phosphorus and monochalcogenide monolayers are an exciting and novel material platform for a host of applications. Key to their crystallinity, monolayers of these materials have a four-fold degenerate structural ground state, and a single energy scale E C (representing the * To whom correspondence should be addressed † Department of Physics. elastic energy required to switch the longer lattice vector along the x− or y−direction) determines how disordered these monolayers are at finite temperature. Disorder arises when nearest neighboring atoms become gently reassigned as the system is thermally excited beyond a critical temperature T c that is proportional to E C /k B . E C is tunable by chemical composition and it leads to a classification of these materials into two categories: (i) Those for which E C ≥ k B T m , and (ii) those having k B T m > E C ≥ 0, where T m is a given material's melting temperature. Black phosphorus and SiS monolayers belong to category (i): these materials do not display an intermediate order-disorder transition and melt directly. All other monochalcogenide monolayers with E C > 0 belonging to class (ii) will undergo a two-dimensional transition prior to melting. E C /k B is slightly larger than room temperature for GeS and GeSe, and smaller than 300 K for SnS and SnSe monolayers, so that these materials transition near room temperature. The onset of this generic atomistic phenomena is captured by a planar Potts model up to the orderdisorder transition. The order-disorder phase transition in two dimensions described here is at the origin of the Cmcm phase being discussed within the context of bulk layered SnSe.

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Section: Resultsmentioning

confidence: 99%

“…Monolayers of layered orthorhombic materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] can become disordered at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers

et al. 2016

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“…The equilibrium configuration of black-phosphorus-like α-GeSe has a puckered structure that forms zigzag chains along the y axis, where the individual layers are weakly coupled t o the adjacent layers by van der Waals forces [19]. For the orthorhombic α-GeSe monolayer structure, four atoms in the unit cell are [33]. The calculated bond lengths and bond angles of the five systems are summarized in Fig.…”

Section: Resultsmentioning

confidence: 99%

Structural and electronic properties of atomically thin germanium selenide polymorphs

et al. 2015

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tronic counterpart to the layered group V semiconductors [25]. Similarly, GeSe is an isoelectronic counterpart to the group V semiconductors and has the same layered structures. α-GeSe nanosheets have been synthesized by several methods and applied in photodetector devices [11,12]. The semiconducting electronic properties of α-GeSe have been confirmed by a recent theoretical investigation [26]. However, the stability and electronic properties of the GeSe monolayers in the other polymorphs have not been investigated. A systematic theoretical investigation of their structures and properties will not only enrich our understanding of the property variations of the polymorphs, but it will also facilitate potential applications. Despite some theoretical and experimental studies of α-GeSe being reported, many important questions still remain unknown: what are the stabilities of the GeSe monolayers in the different phases? How do the electronic properties vary with the different phase structures? In this work, we aim to answer these questions.In this work, by comprehensive density functional theory (DFT) calculations, we report the discovery of the four previously unknown phases of the GeSe monolayer in addition to layered α-GeSe: β-GeSe, γ-GeSe, δ-GeSe, and ε-GeSe. The five polymorphs of GeSe exhibit versatile energy band gaps, which are very significant for broadband optoelectronic and photonic applications. In particular, β-GeSe is an indirect band-gap semiconductor with a band gap of 3.01 eV calculated using the HSE06 exchange-correlation functional. From the band edge alignment, the conduction band minimum (CBM) and valence band maximum (VBM) energies of β-GeSe are −2.54 and −5.55 eV, respectively, which indicates that it is a promising material Using comprehensive density functional theory calculations, we systematically investigate the structure, stability, and electronic properties of five polymorphs of GeSe monolayer, and highlight the differences in their structural and electronic properties. Our calculations show that the five free-standing polymorphs of GeSe are stable semiconductors. β-GeSe, γ-GeSe, δ-GeSe, and ε-GeSe are indirect gap semiconductors, whereas α-GeSe is a direct gap semiconductor. We calculated Raman spectra and scanning tunneling microscopy images for the five polymorphs. Our results show that the β-GeSe monolaye r is a candidate for water splitting.

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“…In Ref. 19 , the VBM is still between the Y and G points with a=3.68Å and b=4.40 A.). The related gaps with GGA and GGA+SOC and the differences between them are summarized in Table I, which are consistent with previous theoretical results 19 .…”

Section: Main Calculated Results and Analysismentioning

confidence: 99%

“…Like other layered materials, 2D SnSe has been recently synthesized 14,15 , which is reported to be a promising 2D semiconductor 16 , and the thermoelectric transport has been also investigated 17 . Besides 2D SnSe, the optical and piezoelectric properties of orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) have been also studied [18][19][20] . Moreover, it is predicted that orthorhombic group IV-VI monolayers are multiferroic with coupled ferroelectricity and ferroelasticity, and GeS and GeSe of them can maintain their ferroelasticity and ferroelectricity beyond the room temperature 21 .…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of orthorhombic group IV–VI monolayers from the first-principles calculations

Guo

Wang

2017

Journal of Applied Physics

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Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, we systematically investigate the thermoelectric properties of orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is included to investigate their electronic transport, which produces observable effects on power factor, especially for n-type doping. According to calculated ZT , the four monolayers exhibit diverse anisotropic thermoelectric properties, although they have similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion, which can be understood by the strength of anisotropy of their respective power factor, electronic and lattice thermal conductivities. Calculated results show that ZT for different carriers of n-and p-type has little difference for GeS, SnS and SnSe. It is found that GeSe, SnS and SnSe show better thermoelectric performance compared to GeS in n-type doping, and SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to a lot of 2D materials, orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) may possess better thermoelectric performance due to higher power factor and lower thermal conductivity. Our work would be beneficial to further experimental study.

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Phosphorene analogues: Isoelectronic two-dimensional group-IV monochalcogenides with orthorhombic structure

Cited by 430 publications

References 59 publications

Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers

Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers

Structural and electronic properties of atomically thin germanium selenide polymorphs

Thermoelectric properties of orthorhombic group IV–VI monolayers from the first-principles calculations

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