Investigation of weak interlayer coupling in 2D layered GeS2 from theory to experiment
Hui‐Juan Yan, Zongbao Li, Shunchang Liu, Xia Wang, Xing Zhang, Ding‐Jiang Xue, Jin‐Song Hu
Abstract
Interlayer coupling as a unique feature for two-dimensional (2D) materials may influence their thickness-dependent physical properties, especially the bandgap due to quantum confinement effect. Widely-studied 2D materials usually possess strong interlayer coupling such as most of transition metal dichalcogenides (TMDs), PtS 2 and so on. However, 2D materials with weak interlayer coupling are rarely referred that mainly focus on ReS 2 , as well as its counterpart ReSe 2 . Here we report a new member of weak interlayer coupling 2D materials, germanium disulfide (GeS 2 ). The interlayer interaction in GeS 2 is investigated from theory to experiment. By density functional theory calculations, we find that this extraordinarily weak interlayer coupling in GeS 2 originates from the weak hybridization of interlayer S atoms. Thickness-dependent Raman spectra of GeS 2 flakes exhibit that the Raman peaks remain unchanged when increasing the thickness; and a small first-order temperature coefficient of −0.00857 cm −1 ·K −1 is obtained from the temperature-dependent Raman spectra. These experimental results further confirm the weak interlayer coupling in GeS 2 .