Abstract
Due to the mismatch of InAs with respect to GaAs, self-assembly quantum dots are formed when more than 1.4 monolayer (ML) of InAs are grown. This self-assembly quantum dots are known as Stranski-Krastanov growth mode. There exists strain in and around this self-assembly quantum dots fabricated by molecular-beam-epitaxy( MBE ). The presence of strain in and around the quantum dots influences the optical properties.This thesis uses ion-channeling method to investigate the structure of quantum dots (InAs), the base of quantum dots (GaAs wafer) and the cap layer of quantum dots in the same time. The results show theirs axes of symmetry are not coincided. It supposes caused by strain in and around the quantum dots.In addition, using the same technique measures the lattice structure of lithium niobate under in situ E-field induced phase transition. But it fails to find any difference of the lattice structure of lithium niobate under phase transition.