부산대학교 도서관

Reduction of crystalline defect density and size is a major issue in optimization of thin film for industrial scale applications. It is particularly hard to achieve defect minimization due to the lack of statistically relevant techniques where defect-induced strain information is also available. In this work, we use a combination of high-resolution transmission electron microscopy and synchrotron X-ray diffraction to investigate the evolution of defects during the growth of highly mismatched cadmium telluride (CdTe) films on silicon(111) as a function of growth temperature and layer thickness. High-resolution transmission electron microscopy was employed to show that the grown layers are epitaxial, following the [111] substrate orientation, and to identify the main defect type (double twins). Detailed reciprocal space maps obtained by synchrotron X-ray diffraction were used to identify the presence of additional intensities near the (113) and (002) CdTe bulk reciprocal space positions caused by these defects. Analysis of these maps allowed to retrieve the strain of the atoms inside defects as well as to evaluate their average size and density. We show that defect density decreases as a function of temperature but increases as a function of layer thickness, while defect size and the elastic energy of the atoms inside each defect increases up to 400 °C.