Choi Hyeong-Kyu, Cha Janghwan, Choi Chang-Gyu, Kim Junghwan, Hong Suklyun
Department of Physics, Graphene Research Institute, and GRI-TPC International Research Center, Sejong University, Seoul 05006, Korea.
Nanomaterials (Basel). 2021 Nov 4;11(11):2960. doi: 10.3390/nano11112960.
Using density functional theory calculations, atomic and electronic structure of defects in monolayer GeS were investigated by focusing on the effects of vacancies and substitutional atoms. We chose group IV or chalcogen elements as substitutional ones, which substitute for Ge or S in GeS. It was found that the bandgap of GeS with substitutional atoms is close to that of pristine GeS, while the bandgap of GeS with Ge or S vacancies was smaller than that of pristine GeS. In terms of formation energy, monolayer GeS with Ge vacancies is more stable than that with S vacancies, and notably GeS with Ge substituted with Sn is most favorable within the range of chemical potential considered. Defects affect the piezoelectric properties depending on vacancies or substitutional atoms. Especially, GeS with substitutional atoms has almost the same piezoelectric stress coefficients eij as pristine GeS while having lower piezoelectric strain coefficients dij but still much higher than other 2D materials. It is therefore concluded that Sn can effectively heal Ge vacancy in GeS, keeping high piezoelectric strain coefficients.
通过密度泛函理论计算，聚焦空位和替代原子的影响，研究了单层GeS中缺陷的原子和电子结构。我们选择IV族元素或硫族元素作为替代原子，它们在GeS中替代Ge或S。结果发现，含有替代原子的GeS的带隙与原始GeS的带隙相近，而含有Ge或S空位的GeS的带隙小于原始GeS的带隙。就形成能而言，具有Ge空位的单层GeS比具有S空位的单层GeS更稳定，值得注意的是，在考虑的化学势范围内，用Sn替代Ge的GeS是最有利的。缺陷根据空位或替代原子影响压电性能。特别是，含有替代原子的GeS具有与原始GeS几乎相同的压电应力系数eij，同时具有较低的压电应变系数dij，但仍远高于其他二维材料。因此得出结论，Sn可以有效地修复GeS中的Ge空位，同时保持较高的压电应变系数。
