Effect of size confinement on CdSe nanocrystals in a GeO 2 glass matrix characterized by photoacoustic spectroscopy

Abstract

Change in the electronic states due to quantum confinement effect was studied for CdSe nanocrystals in a GeO 2 glass matrix by photoacoustic (PA) spectroscopy. The PA technique is a photothermal method which is useful for optical absorption characterization of opaque samples. In the PA method, one can detect an acoustic energy directly proportional to the thermal energy induced by nonradiative processes. The lowest excited energy of CdSe nanocrystals in a GeO 2 glass by quantum confinement effect shifts to lower energy region with the increase of annealing time and temperature, indicating the increase of nanocrystal size. The nanocrystal growing is a diffusion process and the thermal activation energy of ion diffusion during nanocrystal growth is determined to be 1.7 eV.