Luminescence with Local Distribution and Its Possible Mechanism in Zinc Oxide Micro-Crystallites

The spatial luminescence distribution in the ZnO micro-crystallite films deposited on silicon substrates by CVD at room temperature is investigated by the cathedoluminescence (CL) image. It has been observed that the CL image of the samples constitutes a certain pattern. The UV emission pattern projective to the (0001) face of ZnO grains consists of a series of lines nearby the grain boundaries .The included angles between any two adjacent lines are almost 120°. What is more, some luminescent lines form a close hexagon similar to ZnOcrystalline structure. Such a local distribution property shows that the UV emission on as-grown ZnO crystallite should be due to some local
defects congregated to 1010 facets of ZnO grain rather than free exciton recombination.