First-principles study of the structures and fundamental electronic properties of two-dimensional P_0.5As_0.5alloy

Abstract

In this work, the structures, stabilities and electronic properties of 25 possible two‐dimensional (2D) binary P0.5As0.5 alloys were systematically investigated. We found that α‐ and β‐phase are the two most favourable lattice configurations for atomic positional fluctuation. Moreover, we show that the predicted structure IV is slightly more stable than the previously proposed structure III for elementary distribution. Our results indicate that atomic positional fluctuation and elementary distribution are two effective routes to modulating the electronic properties of the 2D P0.5As0.5 alloy with direct or indirect band‐gaps. New ground states for 2D binary P0.5As0.5 alloy.

Phase stability of two-dimensional monolayer As1−xPx solid solutions revealed by a first-principles cluster expansion

“…We reveal that as T → 0 K, monolayer As 1−x P x exhibits a tendency toward phase segregation into its constituent elemental phases without formation of stable ordered structures of α-As 1−x P x and β-As 1−x P x . Furthermore, we demonstrate that the contributions from the lattice vibrations can significantly affect the phase stability of monolayer As 1−x P x , thus leading to the higher thermodynamic stability of the β phase relative to that of the α phase over the whole composition range even at T = 0 K and upon annealing a complete solubility of β-arsenene and β-phosphorene to form a continuous series of disordered solid solution of β-As 1−x P x with 0 x 1 is predicted at T 550 K. These findings suggest not only that the ordered structures of monolayer α-As 1−x P x and β-As 1−x P x , frequently discussed in the previous theoretical studies [14][15][16][17], may not exist in nature, but also that monolayer α-As 1−x P x may merely be metastable with respect to monolayer β-As 1−x P x .…”

“…According to our analysis, an access to the (possibly metastable) ordered structures of monolayer As 1−x P x can be rather limited and they might be achieved in practice only at low temperature. As a consequence, the ordered structures of monolayer As 1−x P x (both α and β phases), regularly considered in the previous theoretical studies [ [14][15][16][17], may not exist in nature, while fabrication of monolayer As 1−x P x by using, for example, epitaxial growth [45,46], chemical vapor deposition [47], and pulse laser deposition [48] techniques, in which the operation temperature can reach several hundred Kelvin, can lead to the formation of disordered solid solutions, in particular β-As 1−x P x , under the thermodynamic equilibrium conditions. Phase separation of the as-synthesized disordered solid solutions of monolayer β-As 1−x P x into the relevant competing phases upon cooling down is, however, likely to be hindered due to a lack of atomic diffusion at low temperature.…”

“…Aside from their pristine states, arsenene and phosphorene have often been considered together from the theoretical viewpoint in the form of monolayer As 1−x P x [14][15][16][17]. In this way, their properties could be effectively fine tuned for relevant applications, as recently demonstrated for three-dimensional (3D) bulk β-As 1−x P x [18][19][20][21].…”

“…In this way, their properties could be effectively fine tuned for relevant applications, as recently demonstrated for three-dimensional (3D) bulk β-As 1−x P x [18][19][20][21]. It should, however, be noted that theoretical investigations on the properties of monolayer As 1−x P x in most cases have so far been restricted only to some certain ordered structures [14][15][16][17], in which the configurational degree of freedom has been completely neglected. In reality, the alloy constituents can exhibit at a given temperature * Annop.E@chula.ac.th and composition different alloying behaviors, i.e., an ordering tendency to form ordered structures/compounds, a clustering tendency toward phase separation, and a mixing tendency to form disordered solid solutions.…”

2D V‐V Binary Materials: Status and Challenges

“…As a result, the carrier mobility of α‐Sb 1− x P x monolayer is tuned to 2 × 10 4 cm 2 V −1 s −1 , twice more than the mobility of black phosphorene . Apart from changing the component percentage, atomic arrangement also effectively modulates the electronic properties . Moreover, the low transport current of 2D AsP is enhanced by appropriate component percentage and atomic positional fluctuation …”