Growth of Single Crystal, Metastable Ge(1-X)sn(x) Alloys and Ge(1-X)sn(x)/ge Strained-Layer Superlattices on Ge(001)2 X 1 by Molecular Beam Epitaxy

75 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.Single-crystal metastable diamond-structure $\rm Ge\sb{1-x}Sn\sb{x}$/Ge strained-layer superlattices (SLS) with x up to 0.24 (the equilibrium solid solubility of Sn in Ge is $<$0.01) were also grown on Ge(001)2x1 substrates using temperature-modulated molecular-beam epitaxy with maximum growth temperatures $\rm T\sb{s}\leq140\sp\circ$C. In-situ reflection high energy electron diffraction combined with post-deposition high-resolution x-ray diffraction (HR-XRD) and XTEM results showed that the $\rm Ge\sb{1-x}Sn\sb{x}(001)2x1$ alloy and Ge(001)2x1 spacer layers were commensurate. In fact, the alloy layers were essentially fully strained with an average in-plane lattice constant mismatch of $(1\pm2)\times10\sp{-5}$ and an average tetragonal strain in the growth direction of $(1.39\pm0.03)\times10\sp{-2}$ as determined from HR-XRD reciprocal-space lattice maps obtained using asymmetric (113) reflections. $\omega$ broadening of the zero-order SLS peak was only 30.1 arc-s full width at half maximum (FWHM), indicating that the degree of mosaicity in these structures was negligible. The intensities and positions of the satellite reflections and finite-thickness interference fringes in HR-XRD 004 rocking curve $\omega$-2$\theta$ scans were in good agreement with simulated curves obtained using a dynamical scattering model.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD