Thickness-dependent phase transition and optical behavior of MoS2 films under high pressure

作     者：Xuerui Cheng Yuanyuan Li Jimin Shang Chuansheng Hu Yufen Ren Miao Liu Zeming Qi 

作者机构：School of Physics and Electronic Engineering Zhengzhou University of Light Industry Zhengzhou China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei China Energy Technologies Area Lawrence Berkeley National Laboratory Berkeley USA 

出 版 物：《Nano Research》 (纳米研究（英文版）)

年 卷 期：2018年第11卷第2期

页      面：855-863页

核心收录：

学科分类：082903[工学-林产化学加工工程] 08[工学] 080203[工学-机械设计及理论] 0829[工学-林业工程] 082201[工学-制浆造纸工程] 0802[工学-机械工程] 0822[工学-轻工技术与工程] 

基　　金：the financial support of National Natural Science Foundation of China Fund for Young Backbone Teachers of Universities in Henan Province Technological Development Grant of Hefei Science Center of CAS National Key Scientific Instrument and Equipment Development Project 

主　　题：molybdenum disulfide high pressure Raman spectroscopy photoluminescence diamond anvil cell 

摘      要：We report the Raman and photoluminescence spectroscopic analysis of layered MoS2 under hydrostatic pressure up to 30 GPa. Unlike previous studies, throughout this work, a special treatment is applied to submerge monolayer, bilayer, multilayer （-200 layers）, and bulk MoS2 samples directly into silicone oil without a supporting substrate in a diamond anvil cell, thereby eliminating possible interference from substrate-film contact. A thickness-dependent trend is observed for the 2Hc-to-2Ha phase transition： The transition pressure increases from 19.0 to 25.6 GPa as the system thickness is reduced from bulk to multilayer MoS2; a further decrease in thickness to the bilayer structure increases the transition pressure to - 36 GPa, as predicted theoretically. This exceeds our measured pressure range, indicating the weakening of interlayer repulsive interactions as the MoS2 film thickness is reduced. Our experiment also reveals a monotonic trend of Raman peak shifting vs. film thickness under applied pressure, suggesting that the Raman vibration modes are more responsive to external pressure in thinner films. The photoluminescence emission peak of the monolayer MoS2 exhibits a blue shift under applied pressure at the rate of 23.8 ***-1. These results show that the structural and optical properties of MoS2 can be effectively modified by applying hydrostatic pressure.