High Pressure XRD And Raman Spectroscopic Studies Of Multilayer And Monolayer Of ReSe₂

Transition Metal Dichalcogenides?TMDs?are semiconductor materials similar to graphene layered structure.Typical transition metal disulfides such as MoS₂ and WS₂ have hexagonal symmetry similar to graphene.Due to their potential applications in optoelectronic devices and photoluminescence,the TMDs materials have drawn much attention.However,The characteristics of ReSe₂ are different from those of typical TMDs such as MoS₂:1,the monolayer has spatial inversion symmetry break;2,multilayer has unordered stacking between layers;3,strong anisotropy in single layer.It is an ideal system for the study of polarization-sensitive optoelectronic devices.In this paper,our research object is ReSe₂.The structure and lattice vibrations of bulk,monolayer and bilayer ReSe₂ are modulated by high pressure diamond anvil technique.The main results of this study are as follows:?1?The high pressure synchrotron radiation X-ray diffraction spectra of bulk ReSe₂ is studied.It's found that bulk ReSe₂ has structure change at 11.75 GPa.The high pressure structure of bulk ReSe₂ is analyzed preliminarily.?2?The high pressure Raman spectroscopy of bulk ReSe₂ shows that the phase transition of bulk ReSe₂ starts at 7.5 GPa and finishes at12.6 GPa.The number of Raman peaks before and after the phase transition is invariant.It is considered that the phase transition of ReSe₂at high pressure belongs to the iso-structural phase transition.?3?The high pressure Raman spectra of monolayer and bilayer ReSe₂ show that all Raman peaks blue shift monotonously with the pressure,no new vibrational peaks appear.There is no structural phase transition of monolayer and bilayer ReSe₂ within the experimental pressure range.It is inferred that the phase transition of bulk ReSe₂ at high pressure is related to interlayer slipping.