A Theoretical Study on the Electronic Structure of ZnSe/ZnS and ZnS/ZnSe Core/Shell Nanoparticles

Abstract

By making use of a density-functional tight-binding (DFTB) method we studied the electronic and optical properties of ZnSe/ZnS and ZnS/ZnSe core/shell nanoparticles. Our emphasis will be on the atomic charge distribution, electronic energy levels, band gap, excitation spectra, and their variation with the thickness of the shell for both ZnSe/ZnS and ZnS/ZnSe core/shell systems. We have made a qualitative comparison of our theoretical results with those of experimental observation on these core/shell systems. Finally, we studied the energetics of diffusion of one Se(S) and S(Se) atoms between the core and the shell in these nanostructures to understand the stabilities of these systems against chemical degradation.