Synthesis of Si-Ge nanoscale structures via deposition of single-source (GeH3)4−nSiHn hydrides

Abstract

Growth of nanoscale islands with distinct Si0.33Ge0.67, Si0.25Ge0.75, and Si0.20Ge0.80 compositions and uniform sizes is conducted on Si(100) via dehydrogenation of the single-source hydrides (H3Ge)2SiH2, (H3Ge)3SiH, and (H3Ge)4Si, respectively. High-spatial-resolution electron energy loss spectroscopy and Raman spectroscopy indicate homogeneous elemental concentrations within and among islands and confirm that their Si-Ge content is predetermined by the stoichiometry of the corresponding precursors. Z-contrast electron microscopy reveals distinct and perfectly epitaxial islands with atomically sharp interfaces grown via a smooth and continuous wetting layer ∼10Å thick. Cross-sectional electron microscopy shows monomodal distributions of islands with defect-free microstructures. Low-energy electron microscopy studies of the film formation reveal that the growth proceeds via the Stranski-Krastanov mode. Assemblies of coherent quantum dots with highly controlled Ge-rich concentrations produced by this method are desirable for their potentially useful optical properties.