Invariable exciton states upon increasing pumping in ZnO quantum dots

• Main Authors: Liao, Wan-Jiun, 廖婉君
• Other Authors: Hsieh, Wen-Feng
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/ztbeg5

碩士 === 國立交通大學 === 光電工程學系 === 98 === ZnO QDs are synthesized by a simple sol-gel method and the average size of QDs can be tailored under solution concentration. Size-dependent blue shifts of photoluminescence give the evidence of the quantum confinement effect. Furthermore, the unchanged spectral profiles of near-bandedge emission (NBE) for a fixed size of ZnO quantum dots (QDs) reveal no signature of biexciton formation and exciton-exciton scattering under excitation density covering three orders of magnitude. These results quite differ from that of the micrometer-sized powder. The intensities of NBE peaks attributed to free exciton and surface bound exciton states exhibit linear dependence on the excitation power density that confirms the invariable exciton states with no effect of two-exciton interaction in ZnO QDs upon increasing the pump intensity.