Influence of the incorporation of metals on the optical properties of MCM-41 and CdSe quantum dots

• Main Authors: Ya-Ping Hsieh, 謝雅萍
• Other Authors: CHI-TE LIANG AND
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/16603525684417786839

碩士 === 國立臺灣大學 === 物理研究所 === 93 === In this thesis, we report the studies of Influence of the incorporation of metals on the optical properties of MCM-41 and CdSe will be reported. Photoluminescence (PL) and photoluminescence excitation (PLE) measurements are employed to characterize their physical properties. This thesis consists of two parts as described as following. 1. Influence of the incorporation of metals on the optical properties of MCM-41 We presented the influence of the incorporation of metals on the optical properties of MCM-41. A series of Al-MCM-41 samples with different Al contents were investigated with photoluminescence (PL) and photoluminescence excitation (PLE). PL measurements revealed an enhancement in intensity by two orders as the Si : Al ratio decreases to 14. The transitions involved with charged oxygen vacancies as well as excess defects have been identified. When Au nanoparticles were deposited onto Al-MCM-41, the PL intensity decreases dramatically. With the help of electron paramagnetic resonance (EPR) and PLE, we found that there is a strong interaction between Au nanoparticles and charged oxygen defects, which is responsible for the reduction of related luminescent intensity. 2. Origin of giant emission enhancement in Au/CdSe nanocomposites A mechanism responsible for the emission enhancement and quenching in Au and CdSe nanocomposites is presented. It is found that the underlying origin arises from the interlay between electron-hole pairs generation by surface plasmon wave and electrons transfer from CdSe quantum dots (QDs) to the Fermi level of Au nanoparticles. Based on our proposed mechanism, the enhancement of CdSe QDs emission can be tuned to reach a factor of up to 140 times, which is the largest value ever reported. It can be used to clarify the confusion in controlling the emission enhancement of semiconductor nanocrystals by using the interaction with surface plasmon of metal nanostructures. The mechanism presented here is very useful for the implementation of semiconductor nanoparticles in optoelectronic devices for applications as high efficiency biolabels and solid state emitters.