Effects of specimen preparation on the cathodoluminescence properties of ZnO nanoparticles

To establish a reliable procedure for the characterization of luminescence from nanomaterials, the cathodoluminescence (CL) observation conditions, such as the packing density of particles and the electron beam energy for irradiation, were examined by using ZnO nanoparticles. The evolutions of the intensities and peak position with the accelerating voltage are strongly affected by the packing density of particles. For the low-density specimen, the band edge emission reaches a maximum at 4 kV where the excitation of each nanoparticle becomes the most effective. On the other hand, the position of band edge emission does not shift for low-density specimen while it changes for high-density specimen. Such artifact may bring serious modifications to the CL data. This work suggests that the specimen preparation and the optimum excitation conditions are the keys for the reliable CL characterization of nanomaterials. (C) 2008 American Institute of Physics.