Two-dimensional Penta-BP5 Sheets: High-stability, Strain-tunable Electronic Structure and Excellent Mechanical Properties

Abstract

Two-dimensional (2D) crystals exhibit unique and exceptional properties and show promise for various applications. In this work, we systematically studied the structures of a 2D boronphosphide (BP) monolayer with different stoichiometric ratios (BPx, x = 1, 2, 3, 4, 5, 6 and 7) and observed that each compound had a stable 2D structure with metallic or semiconducting electronic properties. Surprisingly, for the BP5 compounds, we discovered a rare penta-graphene-like 2D structure with a tetragonal lattice. This monolayer was a semiconductor with a quasi-direct band gap of 2.68 eV. More importantly, investigation of the strain effect revealed that small uniaxial strain can trigger the band gap of the penta-BP5 monolayer to transition from a quasi-direct to direct band gap, whereas moderate biaxial strain can cause the penta-BP5 to transform from a semiconductor into a metal, indicating the great potential of this material for nanoelectronic device applications based on strain-engineering techniques. The wide and tuneable band gap of monolayer penta-BP5 makes it more advantageous for high-frequency-response optoelectronic materials than the currently popular 2D systems, such as transition metal dichalcogenides and black phosphorus. These unique structural and electronic properties of 2D BP sheets make them promising for many potential applications in future nanodevices.

Two-Dimensional Anisotropic C10 Carbon Allotrope with Mechanically Tunable Band Gap

“…Usually with application of strain, the deep conduction band states near Fermi comparatively shifts to lower energy than the lowest conduction band states; this causes change in the nature of band gap between direct or indirect. 23 In some cases similar to the present case, the variation in the valence band is also authoritatively significant to decide the nature of the band gap. On the structural front, a large anisotropy of black phosphorous along with one of the highest carrier mobility has led to highly anisotropic electrical, optical, thermal, and mechanical properties.…”

Anisotropic ultrahigh hole mobility in two-dimensional penta-SiC2 by strain-engineering: electronic structure and chemical bonding analysis

“…It should be noted that the available range of the compressive or tensile strain is determined by both the method to generate strains and the condition of the mechanical failure of strained materials. 52 Common strain-generating methods include lattice mismatch on the substrate, and thermal expansion or mechanical loading, which generally generate strains ranging from À12% to 25%. 53 Further stretching or compression should involve an investigation on the stability of strained materials.…”

Contact properties of a vdW heterostructure composed of penta-graphene and penta-BN2 sheets

“…The unique geometry and novel properties of PG have stimulated a lot of study in the field of 2D materials, leading to the discovery of a new class of 2D materials entirely composed of pentagonal structural units explored theoretically [11][12][13][14][15][16][17][18][19][20][21][22][23][24] and experimentally. 25,26 On the other hand, it has been demonstrated that 2D materials can be used to construct van der Waals (vdW) heterostructures for electronic devices.…”