陳昇暉

III-V solar cells are becoming more widely known for the quality performance that they bring. Hence, an appropriate substrate type is considered very important in their manufacturing. In this thesis, Ge epitaxial films on Si substrates are used as a virtual Ge substrate to manufacture highly efficient III-V solar cells. The two main methods employed are RF magnetron sputtering and cyclic thermal annealing. Ge epitaxial film will be deposited on the Si substrate via the RF magnetron sputtering method due to its lower cost and safety. Cycle thermal annealing is carried out after the deposition of Ge on Si with the aim of reducing the threading dislocation density (TDD) and defects. Due to the mismatch between Si and Ge in terms of the thermal expansion coefficient, after the annealing process, the Ge film in the plane strain will change from compression to tension. We will then analyze the effects of cyclic annealing as well as TDD reduction mechanisms via X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM).