Optical quench of excitonic emission

• Main Authors: Yi-Heng Ho, 何易恒
• Other Authors: Yue-Lin Huang
• Format: Others
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/93086049363739244761

碩士 === 國立東華大學 === 物理學系 === 103 === Direct-band-gap semiconductor can efficiently convert energy. In the form of electromagnetic wave/ light electronic excited state energy release. On the one hand can be applied to the opto-electronic element, on the other hand allows the use of non-destructive optical observation understanding physical processes of electron energy chill out. Recent studies have found that second-band-gap excitation can quenching excitonic emission. Has the potential to develop novel components such as optical switches. The mechanism of the quench effect involving of electron energy state ionization those in the band gap.It provide physical message of crystal defects. This study used ZnO which has a direct band gap as a model system to observe the quench of excitonic emission. Its exciton binding energy (60 meV) is much higher than the thermal energy at room temperature. Therefore, it still has high luminous efficiency at room temperature. In this study, we achieve optical measurement system design / assembly which can change temperature. Establish a CCD photography to capture the spectral and the wavelength calibration method. We observe the quench of excitonic emission in the low temperature and room temperature. Exciton radiation spectrum characteristics change with temperature influence of exciton-phonon coupling and the crystal defects. According to spectral characteristics of neutral donor-bound excitons and phonon replicas excitons established exciton emission spectrum model. To achieve energy gap and exciton-phonon coupling strength by spectral fitting. The results of this study can to check and prove the model of defects affect on the exciton - phonon coupling strength and the mechanism of the quench effect on excitonic emission.