Ar +-laser-assisted subatomic-layer epitaxy of Si

Abstract

Si submonolayer-by-submonolayer epitaxy or subatomic-layer epitaxy (SALE) from Si 2H 6 on Si(001) has been carried out by repeating Si 2H 6 exposure and surface excitation induced by the combination of substrate resistive heating and Ar + laser irradiation. As the average substrate temperature or the laser irradiation power increases, the surface morphology of a grown film changes from a convex shape to a concave shape through a trapezoid shape. The roughness of a flat area of the trapezoid film is within ±2A˚per growth thickness of 100A˚, and a substrate temperature window of∼ 15°C and a laser power window of∼ 0.25W, where such a flat growth surface and a constant growth rate are obtained, has been observed. The ranges of these windows have been estimated to correspond to the same variation of the surface temperature in the laser irradiation area during the laser irradiation. This result together with the result of the analyses on growth thickness distribution profiles suggests that the laser irradiation works as a thermal effect. Thus, in the Ar +-laser-assisted SALE method, the growth surface morphology then the growth mode is controlled by the surface temperature during the laser irradiation. An Ar + laser is a useful tool to control the surface temperature.