| Summary: | 碩士 === 國立中興大學 === 光電工程研究所 === 101 === This thesis mainly uses photoreflectance method to study the optical property of InAs/GaAs quantum dots, which are grown by hydrogen-assisted molecular beam epitaxy.
A. V. Katkova et al. in 2011 published a thesis which mainly discusses the InAs/GaAs quantum dots structure and studies how to improve the optical efficiency. It proves that if we add hydrogen atoms during the process of growing GaAs bulk, the nonradiative recombination centers are decreased, and it could largely increase the PL intensity in InAs/GaAs structure .However, there is no direct evidence to prove the relation between adding the hydrogen atoms and the defect density in the InAs/GaAs quantum dots, therefore photoreflectance is used to study this issue.
In addition, we use the pump beams with different wavelengths to excite the samples to study the variations of oscillation features. After this treatment, the quantum dots signals of PR spectra were observed, then we use Origin software to fit the QD signals, which correspond to the quantum dots emission in the PL spectra.
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