Investigation of anisotropic mechanical, electronic, and charge carrier transport properties of germanium-pnictogen monolayers

Abstract

Recently, novel two-dimensional (2D) GeP and GeAs systems have been fabricated by mechanical exfoliation and utilized in various applications. These developments have brought the 2D germanium-pnictogens, C2/m-GeX (X = N, P, As, Sb, and Bi) structures into the limelight. In this study, we systematically investigate the structural, mechanical, electronic, and charge carrier transport properties of GeX monolayers by using first-principles methods. Our results show that the considered systems are dynamically stable and possess anisotropic physical properties. Examined structures are found to be flexible, and their mechanical strength and stiffness decrease down the group-V, in line with the trends of the bond strength, cohesive energy, charge transfer, and electron localization function. Additionally, the zigzag in-plane direction is mechanically superior to the armchair direction. The electronic band structure calculations based on HSE06 hybrid functional with the inclusion of spin-orbit coupling indicate that GeX monolayers are either direct or quasi-direct semiconductors with band gaps lying within the infrared and visible spectrum. The estimated charge carrier mobilities are highly anisotropic and also differ significantly depending on the structure and carrier type. These unique properties render GeX monolayers as suitable 2D materials for flexible nanoelectronic applications.

Two-dimensional AlXY (X = S, Se, and Y = Cl, Br, I) monolayers: promising photocatalysts for water splitting with high-anisotropic carrier mobilities

“…To validate the reliability of our calculation method, the elastic constants of graphene were also calculated and the corresponding results are given in Table 2, which are in good agreement with the previous results. 44 To gain further insights into the mechanical properties of the AlXY monolayers, Young's modulus Y ( θ ) and Poisson's ratio v ( θ ) with respect to the in-plane angle ( θ ) were calculated using the following formulae: 45 where s and c represent sin( θ ) and cos( θ ), respectively. The orientation-dependent Y ( θ ) and v ( θ ) are presented in Fig.…”

First-principles study on the photocatalytic field of two-dimensional Janus BiSY (Y = I, Br, Cl) monolayers

“…Examining the elastic constants provides a crucial understanding of the different mechanical properties associated with BiSY (Y = I, Br, Cl), such as its stiffness, resistance to deformation, and response under applied mechanical forces. Our calculations adhere to the formulation: 51,52 …”

Two-dimensional β-noble-transition-metal chalcogenide: novel highly stable semiconductors with manifold outstanding optoelectronic properties and strong in-plane anisotropy

“…10, give monolayer b-NX a exible quality. 48 Additionally, we calculated the effective masses of holes and electrons of the VBM and CBM along different directions for the different b-NX materials. The equation used in the calculation is shown in eqn (3), where ħ is the reduced Planck constant, and k and E represent the wave vector and corresponding energy, respectively.…”

“…That is to say, in b-NX, both the N (4) -X and N (2) -X bonds are composed of partial ionic bonds and partial covalent bonds, and there are lone-pair electrons around the X atoms. 45,[48][49][50] Such LPEs are more inclined to be between layers, which gives b-NX excellent conductivity. Additionally, the linear N (2) channel is intermittent along the y-direction and continuous along the x-direction, whereas the square-planar N (4) channel is the opposite.…”