Step Bunching, Chemical Ordering, and Diffusivity in Si1−yCy Heteroepitaxy

ABSTRACTThe growth of Si1−yCy on Si(001) and Si(118) surfaces is investigated experimentally and theoretically. A step instability is found on (118) surfaces leading to step bunching, under low C-concentrations. This behavior is explained by increased diffusivity of Si dimers in the vicinity of carbon. Self adjusting step bunches are found in kinetic Monte Carlo simulations with ordering of the carbon along nearly (001) planes. Experimental parameters (i.e., temperature, flux rate, and tilt angle of the substrate), which are controllable experimentally, can be used to adjust the length scale of the step bunching.