INITIAL GROWTH-PROCESSES IN THE EPITAXY OF GE AND GEH4 ON OXIDIZED SISUBSTRATES

The heteroepitaxial growth of Ge on (100) Si in a horizontal, atmosphe ric pressure metallorganic vapor-phase epitaxy reactor is reported usi ng germane GeH4 (0.1% in H-2). A particularly crucial parameter for ge rmanium deposition on silicon is the time for the onset of epitaxial g rowth, the incubation time. The time was measured at substrate tempera tures between 450 and 600 degrees C. At a substrate temperature of 450 degrees C an incubation time of 520 s was found and for the subsequen t epitaxy growth rates of 50 nm/min were determined by Nomarski micros copy and electron diffraction. The existence of residual oxide in the reactor chamber forming an in situ SiO2 layer was evaluated by x-ray p hotoemission spectroscopy. To obtain a more thorough understanding of the gas- and solid-phase composition of Ge, Si, and oxygen the Gibbs e nergy of the system was calculated for various growth temperatures. It was concluded that SiO2 molecules are reduced by GeH4 molecules durin g the incubation period.