Chemical routes to Ge/Si(100) structures for low temperature Si-based semiconductor applications

The authors describe very low temperature (350-420 degrees C) growth of atomically smooth Ge films (0.2-0.4 nm roughness) directly on Si(100) via gas-source molecular beam epitaxy. A carefully tuned admixture of (GeH3)(2)CH2, possessing unique pseudosurfactant properties, and conventional Ge2H6 provides unprecedented control of film microstructure, morphology, and composition. Formation of edge dislocations at the interface ensures growth of virtually relaxed monocrystalline Ge films (similar to 40-1000 nm thick) with a threading dislocation density less than 10(5) cm(-2) as determined by etch pit measurements. Secondary ion mass spectroscopy showed no measurable carbon incorporation indicating that C desorbs as CH4, consistent with calculated chemisorption energies. (c) 2007 American Institute of Physics.