| Summary: | 碩士 === 國立臺灣師範大學 === 物理學系 === 102 === In this thesis, we study the carrier dynamics of (i) GaN nanorod/film, and (ii) strontium titanate (SrTiO3)/strontium ruthenate (SrRuO3) heterostructures by utilizing time-resolved pump-probe spectroscopy. In the first part, the photoluminescence spectrum of GaN thin film exhibits side peaks at 3.36 eV and 3.30 eV besides bandgap 3.40 eV, while the spectrum of GaN nanorods shows only one peak at 3.40 eV. These phenomena were also observed in wavelength-dependent pump probe traces, and the absorption peaks were resolved for GaN thin film and nanorods. The carrier diffusion and surface trapping effects have also been investigated. The second part, two different pump-probe spectroscopy setups were employed to study STO/SRO heterostructures. We demonstrate that SRO beneath STO thin film can be served as phonon transducer. According to the Brillouin scattering, the refractive index of STO around near UV region was accurately obtained. In the temperature-dependent experiment (80K~ 300 K), we discovered dramatic changes of time-resolved reflectivity during the phase transition of STO (105 K) and SRO (160 K), respectively. The lifetimes of phonon were also shorter during the phase transitions of both materials.
|
|---|
