Morphological control and structural characteristics of crystalline Ge-C systems: Carbide nanorods, quantum dots, and epitaxial heterostructures

Chemical precursors are used to grow crystalline Ge-C materials with unusual morphologies that depend on the molecular design of the precursor and the C concentration. Ge-C nanorods with overall C content of about 13-15 at. % and lattice constants close to that of pure Si grew very rapidly from the surface of a 40 nm Ge-C epitaxial film. Coherent carbide islands are formed after epitaxial growth of 20 nm Ge_1-xC_x (x = 9 at. %) on (100)Si. Lower reaction temperatures resulted in extremely low growth rate of epitaxial Ge_1-xC_x (x = 3-5 at. %) heterostructures with very flat surfaces implying two-dimensional layer-by-layer growth. The use of precursor chemistry as reported here to control morphology and composition in the Ge-C system may provide a simple and reliable synthetic route to a new family of Si-based heterostructures.