Optical studies of ZnSe nanocrystals in potassium borosilicate glass matrices

We have prepared ZnSe nanocrystals embedded in potassium borosilicate glass matrices in concentrations up to 14 wt%. The optical and electronic properties of these nanocrystals as a function of the fabrication process were investigated with High Resolution Transmission Electron Microscopy (HRTEM) and various optical techniques including absorption, photoluminescence, and excitation spectroscopy, and photoluminescence lifetime measurements, HRTEM confirms the presence of nanocrystals and indicates an average diameter size of 50 Angstrom. The majority of the photoluminescence extends throughout the visible and is highly red-shifted from the absorption-edge, indicating emission from trap states such as Se vacancies. Contributions from the ZnSe nanocrystals as well as the borosilicate glass matrix are also observed. Exponential and biexponential photoluminescence decays are observed with decay times ranging from a few nanoseconds to a few hundred nanoseconds. The significance of these results to the optical and electronic properties of the ZnSe nanocrystals and their relevance as luminescent materials for light emitting applications will be discussed.