Phase stability and properties of two-dimensional phosphorus carbide, ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ ($0\le x\le 1$), are investigated using the first-principles method in combination with cluster expansion and Monte Carlo simulation. Monolayer ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ is found to be a phase-separating system which indicates difficulty in fabricating monolayer ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ or crystalline ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ thin films. Nevertheless, a bottom-up design approach is used to determine the stable structures of ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ of various compositions which turn out to be superlattices consisting of alternating carbon and black phosphorene nanoribbons along the armchair direction. Results of first-principles calculations indicate that once these structures are produced, they are mechanically and thermodynamically stable. All the ordered structures are predicted to be semiconductors, with band gap (Perdew-Burke-Ernzerhof) ranging from 0.2 to 1.2 eV. In addition, the monolayer ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ are predicted to have high carrier mobility, and high optical absorption in the ultraviolet region which shows a redshift as the P:C ratio increases. These properties make two-dimensional ${\mathrm{P}}_x{\mathrm{C}}_{1-x}$ promising materials for applications in electronics and optoelectronics.

中文翻译：

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单层碳化磷（PxC1-x）的相图和超晶格结构

二维碳化磷的相稳定性和性能 ${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$ （$0\le X\le \mathrm{1个}$），是使用第一原理方法结合簇扩展和蒙特卡洛模拟进行研究的。单层${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$ 被发现是一种相分离系统，表明难以制造单层膜 ${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$ 或结晶 ${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$薄膜。尽管如此，仍采用自下而上的设计方法来确定结构的稳定结构。${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$各种成分组成的超晶格是沿着扶手椅方向由交替的碳和黑色磷光体纳米带组成的。第一性原理计算的结果表明，一旦产生了这些结构，它们在机械和热力学上都是稳定的。预测所有有序结构均为半导体，带隙（Perdew-Burke-Ernzerhof）的范围为0.2至1.2 eV。另外，单层${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$据预测，它们具有高的载流子迁移率，并且在紫外区域具有高的光吸收，随着P：C比的增加，该区域显示出红移。这些特性使二维${\mathrm{P}}_X{\mathrm{C}}_{\mathrm{1个}-X}$ 在电子和光电子领域中应用前景广阔的材料。