Using first-principles calculations, we study the structural, electronic and optical properties of the monolayer, bilayer and trilayer germanium monosulfide GeS. The results reveal an indirect semiconducting band gap for the monolayer and trilayer GeS, whereas the gap is direct for the bilayer GeS. Both the generalized gradient approximation and the screened hybrid functionals assess a decrease in band energy as the number of layers is improved. Furthermore, due to the high buckling of lattice structures, the optical spectra show significant degree of anisotropy. The number of layers engineers key optical parameters including the refractive index, the reflectivity absorption and provides the layered GeS with excellent absorption in the low energy region, namely the visible and UV range of the electromagnetic spectrum. Accordingly, 2D hexagonal GeS few-layers can be used as a highly promising material in the optoelectronic, ultraviolet optical nanodevices and photovoltaics.

使用第一性原理计算，我们研究了单层，双层和三层单硫化锗GeS的结构，电子和光学性质。结果揭示了单层和三层GeS的间接半导体带隙，而双层GeS的间隙是直接的。无论是广义梯度近似和筛选杂交函作为层的数量提高评估带能量的减少。此外，由于晶格结构的高屈曲，光谱显示出很大程度的各向异性。层数是工程师的关键光学参数，包括折射率，即反射率吸收，并为层状GeS在低能量区域（即电磁光谱的可见光范围和UV范围）提供出色的吸收。因此，二维六角形GeS少数层可以用作光电子，紫外线光学纳米器件和光伏中的高度有前途的材料。