| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 106 === Due to the 4.2% lattice mismatch between Ge and Si, general direct growth will result in a higher Threading Dislocation Density (TDD), and the need to introduce the complicated composition gradually varied SiGe buffer layer makes the process cost high.
In this study, the low-cost liquid phase epitaxy (LPE) elemental composition self-modulated method is used to complete the Ge-on-Si heteroepitaxy. Moreover, epitaxial lateral overgrowth (ELO) is performed through the powderization of Si solute and achieve the purpose of improving the surface roughness. For lateral selective epitaxial growth, in order to prevent the SiO2 mask from peeling off at the customary saturation temperature of 950℃, we reduce the temperature and use the powdered Si solute to increase the melting rate of the solvent Sn to Si; in addition, by varying the growth time with the cooling rate to seek the best epitaxial parameters for high quality Ge-on-Si substrates.
In addition to the etch pit density (EPD) of the sample, the scanning electron microscopy (SEM), Atomic Force Microscope (AFM), and X-ray Diffraction (XRD) are also used to analyze the characteristics of the epitaxial layer and to confirm the integrity of the epitaxial structure prepared in this study. At present, the defect-free pure Ge layer can be prepared by using the ELO selective growth technology, and especially the surface roughness was reduced to about 5nm.
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