Raman spectroscopy of GaSe and InSe post-transition metal chalcogenides layers

III-VI post-transition metal chalcogenides (InSe and GaSe) are a new class of layered semiconductors, which feature a strong variation of size and type of their band gaps as a function of number of layers (N). Here, we investigate exfoliated layers of InSe and GaSe ranging from bulk crystals down to monolayer, encapsulated in hexagonal boron nitride, using Raman spectroscopy. We present the N-dependence of both intralayer vibrations within each atomic layer, as well as of the interlayer shear and layer breathing modes. A linear chain model can be used to describe the evolution of the peak positions as a function of N, consistent with first principles calculations.

Automated summary

In this study, the N-dependence of intralayer vibrations and interlayer modes in layers of InSe and GaSe encapsulated in hexagonal boron nitride was investigated using Raman spectroscopy. The peak positions evolution as a function of N can be described by a linear chain model, which is consistent with first principles calculations.