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Role of size, shape, crystal structure and dimension on the energy band gap expansion in nanostructures
Monika Goyal
A unified qualitative model is presented to study the impact of size, shape, crystal structure and dimension on the energy band gap of nanostructures. The formulated approach is based on the Bond energy model used to determine the relative melting temperature of nanosolids. The model approach depends on size, dimension, crystal structure and shape of nanomaterial.The study is done on AlN, AlP, AlAs, GaN, GaP, GaAs. The formulation is obtained using the Arrhenius relation of electrical conductivity and is used to determine energy band gap expansion with respect to diameter/height of the nanostructures of different shapes. Depending on the shape of the nanomaterial, the surface area to volume ratio varies in nanomaterials that results in the change in the energy band gap value in nanostructure of same size. The study reveals that parameters viz. size, size, shape, crystal structure and dimension results in change in energy band gap value that enhance the possibility of tuning the optical properties of nanostructures. The model results are compared with the simulated and experimental data available and good agreement of model results with compared data is observed. The shifts in band gap energy of valence and conduction band is determined from the study in GaP nanosolid. Drop in size at nano level results in increase the band gap energy leading to Raman blue shift.
Keywords: Size, Shape parameter, band gap expansion, dimension, crystal structure