Nanocomposites and nanomaterials 

Indium Selenide – an Evolution of the Electronic and Dynamical Properties under Transition from Bulk Crystal to Monolayers

L.Yu. Kharkhalis1, K.E.Glukhov1, T.Ya.Babuka1,2,
 M.V. Lyakh1 

1 Institute of Physics and Chemistry of Solid State, Uzhgorod National University, 
54 Voloshin St., 88000 Uzhgorod, Ukraine, 
E-mail: lkharkhalis@gmail.com

2 Institute of Physics, Faculty of Mathematics and Natural Science, Jan Dlugosz University in Czestochowa, Al. Armii Krajowej 13/15, 42-200 Czestochowa, Poland

Among various indium selenide materials currently under investigation, the β-InSe crystals have attracted considerable interest since they are potential candidates for the application of their physical properties in nonlinear optics, solar energy, and spintronics. Owing to their unique intrinsic structures, indium selenides were utilized for the construction of the heterostructures so as β-InSe/graphene, InSe/SiC, and nanotubes. Nowadays, the investigations of the structural, electronic and dynamical properties of the nanotubes and thin indium selenide flakes are interested due to their use in the thermoelectric and ultraviolet photodetectors [1]. While slab and bulk β-InSe crystals show different electronic and dynamical features, how they transform from monolayer to bulk is an important issue, which can be explored by changing the number of layers. 
In the present work, we aimed at ab initio calculations of the evolution of the electronic, dynamical and elastic properties under transitions from bulk β-InSe layered crystal to its monolayers. The influence of the number of layers on the shape of the band structure in the vicinity of the main extrema of the valence band and conduction band and also on the phonon dispersion curves and phonon density have been analyzed. We carried out the Raman and IR spectra calculations and constructed the vectors of atom displacements corresponding to normal vibration active in these spectra. For the first time, the calculations of Born effective charges, dielectric constants, and velocities of the sound propagations were carried out for the hexagonal crystal β-InSe and its monolayers.

1.	Hai G.S, Yuan X.W., Yu L.Y., Guang B.Z. Structural, Electronic, and Thermoelectric Properties of InSe Nanotubes: First-Principles Calculations // J. Phys. Chem. C. – 2012.– 116.– P. 3956-3961.