Knowledge about chemical functionalization is of fundamental importance to design novel two-dimensional topological insulators. Despite theoretical predictions of quantum spin Hall effect (QSH) insulator via chemical functionalization, it is quite challenging to obtain a high-quality sample, in which the toxicity is also an important factor that cannot be ignored. Herein, using first-principles calculations, we predict an intrinsic QSH effect in amidogen-functionalized Bi/Sb(111) films (SbNH₂ and BiNH₂), characterized by nontrivial Z₂ invariant and helical edge states. The bulk gaps derived from p_x,y orbitals reaches up to 0.39 and 0.83 eV for SbNH₂ and BiNH₂ films, respectively. The topological properties are robust against strain engineering, electric field, and rotation angle of amidogen, accompanied with sizable bulk gaps. Besides, the topological phases are preserved with different arrangements of amidogen. The H-terminated SiC(111) is verified as a good candidate substrate for supporting the films without destroying their QSH effect. These results have substantial implications for theoretical and experimental studies of functionalized Bi/Sb films, which also provide a promising platform for realizing practical application in dissipationless transport devices at room temperature.

中文翻译：

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酰胺基功能化对Bi / Sb（111）薄膜中量子自旋霍尔效应的影响

有关化学功能化的知识对于设计新颖的二维拓扑绝缘体至关重要。尽管通过化学功能化对量子自旋霍尔效应（QSH）绝缘子进行了理论预测，但要获得高质量的样品还是非常具有挑战性的，其中毒性也是一个不可忽视的重要因素。在这里，使用第一性原理计算，我们预测了由酰胺基官能化的Bi / Sb（111）薄膜（SbNH ₂和BiNH ₂）固有的QSH效应，其特征是非平凡的Z ₂不变和螺旋边缘态。对于SbNH ₂和BiNH _，从p _x，y轨道得出的体隙达到0.39和0.83 eV₂部电影。拓扑特性对于应变工程，电场和酰胺原的旋转角具有强大的抵抗力，并具有较大的体积间隙。此外，拓扑阶段以不同的酰胺基形式保留。氢封端的SiC（111）被证明是支撑薄膜而不破坏其QSH效果的良好候选衬底。这些结果对功能化Bi / Sb薄膜的理论和实验研究具有重大意义，这也为在室温下实现无损耗传输设备中的实际应用提供了有希望的平台。