Pressure confinement effect in MoS2 monolayers.
With ever increasing interest in layered materials, molybdenum disulfide has been widely investigated due to its unique optoelectronic properties. Pressure is an effective technique to tune the lattice and electronic structure of materials such that high pressure studies can disclose new structural and optical phenomena. In this study, taking MoS2 as an example, we investigate the pressure confinement effect on monolayer MoS2 by in situ high pressure Raman and photoluminescence (PL) measurements. Our results reveal a structural deformation of monolayer MoS2 starting from 0.84 GPa, which is evidenced by the splitting of E(1)2g and A1g modes. A further compression leads to a transition from the 1H-MoS2 phase to a novel structure evidenced by the appearance of two new peaks located at 200 and 240 cm(-1). This is a distinct feature of monolayer MoS2 compared with bulk MoS2. The new structure is supposed to have a distorted unit with the S atoms slided within a single layer like that of metastable 1T'-MoS2. However, unlike the non-photoluminescent 1T'-MoS2 structure, our monolayer shows a remarkable PL peak and a pressure-induced blue shift up to 13.1 GPa. This pressure-dependent behavior might enable the development of novel devices with multiple phenomena involving the strong coupling of the mechanical, electrical and optical properties of layered nanomaterials.
State Key Laboratory of Superhard Materials, College of Physics, Jilin University, No. 2699 Qianjin Street, Changchun 130012, P.R. China. zhouqiang@jlu.edu.cn.
Fangfei
F
Li
Yalan
Y
Yan
Bo
B
Han
Liang
L
Li
Xiaoli
X
Huang
Mingguang
M
Yao
Yuanbo
Y
Gong
Xilian
X
Jin
Baoli
B
Liu
Chuanrui
C
Zhu
Qiang
Q
Zhou
Tian
T
Cui