| Summary: | 碩士 === 國立彰化師範大學 === 物理學系 === 106 === Abstract
CuIn1-xGaxS2 (CIGS) nanocrystals (NCs) were synthesized by a heating method. Lattice structure and optical properties of the samples were measured by X-ray diffraction, absorption spectroscopy, transmission electron microscopy (TEM) and Raman spectroscopy. X-ray diffraction results showed that the CIGS NCs have chalcopyrite structure, and theirlattice constant was related to the molar ratio of Ga in the NCs. The higher the molar ratio of Ga, the smaller the lattice constant. The size of the NCs was confirmed to be about 15 nm by X-ray diffraction and TEM. The energy gap of the NCs determined by absorption spectra was between 1.05 to 1.72 eV. Results of absorption measurement also showed that the energy gap was a quadratic function of the mole ratio of Ga. The higher the molar ratio of Ga, the larger the energy gap. The results of Raman spectroscopy showed that the main vibration signal of the CIGS NCs shifted from 178 cm-1 to 186 cm-1 as the molar ratio of Ga increased. The frequency of this main vibration mode was related to the atomic mass as well as the force constant of bond between atoms. A theoretical model was used to analyses the effect of the atomic mass on the vibration mode with fixed force constant, and the effect of the force constant on the vibration mode with fixed atomic mass, respectively. The theoretical predictions were in good agreement with the experimental data.
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