Surface phonons in two-layer thin films of GeSe

TL;DR

This study uses ab initio calculations to analyze the surface phonon spectra of two-layer GeSe thin films, revealing the nature of surface vibrational modes in layered semiconductors.

Contribution

It provides the first ab initio analysis of surface phonon spectra in two-layer GeSe films using Density Functional Perturbation Theory.

Findings

Identification of surface phonon modes in gaps and pockets

Characterization of surface modes outside bulk phonon boundaries

Insights into surface vibrational properties of layered GeSe

Abstract

This paper presents ab inition calculations of the surface phonon spectra of GeSe layered semiconductor compound, based on the Density Functional Perturbation Theory (DFPT). The surface has been imitated by a structure of periodically arranged slabs of two layers of GeSe crystal separated from other identical layers by the layers of vacuum sufficiently wide to ignore the effect of the upper boundary of the double-layer upon its lower boundary. We discuss the character of the surface modes located in the gaps, in the pockets, and in the area of allowed phonon states for the bulk GeSe crystals, as well as outside (above and below) the boundaries of the bulk phonon states.