Gallium arsenide (GaAs), a typical covalent semiconductor, is widely used in the electronic industry, owing to its superior electron transport properties. However, its brittle nature is a drawback that has so far significantly limited its application. An exploration of the structural deformation modes of GaAs under large strain at the atomic level, and the formulation of strategies to enhance its mechanical properties is highly desirable. The stress-strain relations and deformation modes of single-crystal and nanotwinned GaAs under various loading conditions are systematically investigated, using first-principles calculations. Our results show that the ideal strengths of nanotwinned GaAs are 14% and 15% higher than that of single-crystal GaAs under pure and indentation shear strains, respectively, without producing a significantly negative effect in terms of its electronic performance. The enhancement in strength stems from the rearrangement of directional covalent bonds at the twin boundary. Our results offer a fundamental understanding of the mechanical properties of single crystal GaAs, and provide insights into the strengthening mechanism of nanotwinned GaAs, which could prove highly beneficial in terms of developing reliable electronic devices.

砷化镓（GaAs）是一种典型的共价半导体，由于其优越的电子传输特性，在电子工业中得到广泛应用。然而，其脆性是迄今为止显着限制其应用的一个缺点。在原子水平上探索大应变下 GaAs 的结构变形模式，并制定提高其机械性能的策略是非常可取的。使用第一性原理计算系统地研究了在各种负载条件下单晶和纳米孪晶 GaAs 的应力-应变关系和变形模式。我们的结果表明，在纯剪切应变和压痕剪切应变下，纳米孪晶 GaAs 的理想强度分别比单晶 GaAs 高 14% 和 15%，不会对其电子性能产生明显的负面影响。强度的提高源于双晶界处定向共价键的重排。我们的研究结果提供了对单晶 GaAs 机械性能的基本理解，并提供了对纳米孪晶 GaAs 强化机制的见解，这对于开发可靠的电子器件非常有益。