| Abstract | High-quality SiGe epitaxial layers have been grown on low-defect-density bulk single-crystal SiGe substrates using low-temperature ultrahigh vacuum chemical vapor deposition (UHV/CVD). The layers were simultaneously grown on Si substrates for comparison. Various techniques, including high-resolution x-ray diffraction (HRXRD), photoluminescence (PL), Auger electron spectroscopy, atomic force microscopy (AFM), and cross-sectional transmission electron microscopy (XTEM) were used to characterize the structural quality of the materials. There is good agreement between different techniques for the determination of the composition and thickness of the layers. HRXRD, PL, and XTEM results confirm that the materials deposited are high-quality single-crystal epilayers. The surface root-mean-square roughness measured by AFM is less than 0.4 nm, indicating very smooth surfaces. A thin undoped Si buffer layer was found to improve the structural quality of the layers. The bulk crystal SiGe substrates are useful for the growth of thick lattice-matched and strained SiGe epilayers. |
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