Boron Monochalcogenides; Stable and Strong Two-Dimensional Wide Band-Gap Semiconductors

Abstract

In this short communication, we conducted first-principles calculations to explore the stability of boron monochalcogenides (BX, X = S, Se or Te), as a new class of two-dimensional (2D) materials. We predicted BX monolayers with two different atomic stacking sequences of ABBA and ABBC, referred in this work to 2H and 1T, respectively. Analysis of phonon dispersions confirm the dynamical stability of BX nanosheets with both 2H and 1T atomic lattices. Ab initio molecular dynamics simulations reveal the outstanding thermal stability of all predicted monolayers at high temperatures over 1500 K. BX structures were found to exhibit high elastic modulus and tensile strengths. It was found that BS and BTe nanosheets can show high stretchability, comparable to that of graphene. It was found that all predicted monolayers exhibit semiconducting electronic character, in which 2H structures present lower band gaps as compared with 1T lattices. The band-gap values were found to decrease from BS to BTe. According to the HSE06 results, 1T-BS and 2H-BTe show, respectively, the maximum (4.0 eV) and minimum (2.06 eV) electronic band gaps. This investigation introduces boron monochalcogenides as a class of 2D semiconductors with remarkable thermal, dynamical, and mechanical stability.

Two-dimensional boron monochalcogenide monolayer for thermoelectric material

“…From our calculations, it is observed that our calculated parameters are in good agreement with previous work. 31 Cohesive energy was calculated by using the formula given below:…”

“…S1 (ESI †) shows the obtained phonon dispersion curves, which show good agreement with previous investigations. 31 Most of the BX monolayers are free from imaginary frequencies, except BTe (2H). BTe (2H) can be considered dynamically stable and includes very low imaginary frequencies (À0.224 THz) close to G, due to numerical anomalies that would be improved if a larger supercell or increased k-points were used for calculation.…”

“…Boron monochalcogenides are recently proposed materials utilizing density functional theory (DFT) which contain two phases, 1T and 2H. 31 We have systematically investigated the thermoelectric properties of both the 1T and 2H phases of boron monochalcogenides. This present study includes the structural, vibrational, electronic and thermoelectric properties of boron chalcogenides.…”

Eighteen functional monolayer metal oxides: wide bandgap semiconductors with superior oxidation resistance and ultrahigh carrier mobility

“…All 18 MMOs are either semiconductors or insulators, with bandgaps ranging from 1.22 to 6.48 eV, which are comparable to the values of other wide band-gap semiconducting 2D materials, like boron monochalcogenides (with bandgap in the range of 2.06-4.00 eV). 42 In particular, Thus, these MMOs are suitable for potential applications as electronic and optoelectronic devices to operate at much higher voltages, frequencies and temperatures than the conventional semiconductor materials like silicon and gallium arsenide. [43][44][45][46] On the other hand, ZrO 2 and HfO 2 monolayers possess exceptionally large bandgaps of 6.0 and 6.48 eV, and should be considered as 2D insulators.…”

Phase diagrams and electronic properties of B-S and H-B-S systems under high pressure

“…The semiconducting Ibam BH phase transforms into the metallic P6/mmm structure, which also becomes a superconductor with a T c of 14.1 ∼ 21.4 K at 168 GPa [56]. For B-S compounds, most of the current studies are focused on structures and electronic properties at ambient pressure [58][59][60][61][62]. Structural phase transitions of BS and B 2 S 3 have been studied below 50 GPa [63][64][65].…”