Theoretical Prediction for Band Gap of Semiconducting Nanoparticles

In the present study, a well-established relation between the band gap of low dimensional solid and its cohesive energy has been used to calculate the band gap variation at nano level. The different thermodynamical models proposed for the cohesive energy do not consider the unsaturated bonds of surface atoms, the shape of the nanoparticle and the packing density of the corresponding crystal simultaneously. Extending the bond energy model, a simple theoretical model for the cohesive energy has been proposed which incorporate all the above-mentioned properties simultaneously and hence getting a more comprehensive relation between the band gap and the characteristics of the nanoparticle. We have computed bandgap of compound semiconducting nanosolids ZnE and CdE, (E=S, Se, Te) in different shapes. It is found that band gap expands as the particle size decreases and the shape deviates more from spherical one. A close agreement between our calculated results and the available experimental da