The size-dependent phonon frequency of semiconductor nanocrystals

Abstract

A model, without adjustable parameters, describing the size-dependent phonon frequency of semiconductor nanocrystals is established based on the size-dependent force constant and thus the size-dependent bond length and bond energy of nanocrystals. This model shows frequency shifts as the size of the crystals decreases. Our predictions agree with the results of experiments for the blue shift of TiO2 nanoparticles, Si and InP quantum dots. The model will be useful for understanding the origins of the phonon behaviour of nanocrystals and the effect of the thermodynamic parameters on the phonon frequency.