Si—Ge materials are grown on Si(100) with Ge-rich contents (Ge>50 at. %) and precise stoichiometries SiGe, SiGe2, SiGe3 and SiGe4. New hydrides with direct Si—Ge bonds derived from the family of compounds (H3Ge)xSiH4-x (x=1-4) are used to grow uniform, relaxed, and highly planar films with low defect densities at unprecedented low temperatures between about 300-450° C. At about 500-700° C., SiGex quantum dots are grown with narrow size distribution, defect-free microstructures and highly homogeneous elemental content at the atomic level. The method provides for precise control of morphology, composition, structure and strain. The grown materials possess the required characteristics for high frequency electronic and optical applications, and for templates and buffer layers for high mobility Si and Ge channel devices.