Step Bunching during SiGe Growth on Vicinal Si(111) Surfaces

Abstract

AbstractWe investigate step bunching during SiGe growth on vicinal Si(111) surfaces. Step bunching occurs irrespective of the misorientation angle and direction of the vicinal surface, the growth temperature, and the Ge concentration. At 550°C, the average number of the steps in the bunch increases with the Ge concentration. After growth of 10-nm-thick SiGe layers, twodimensional islands are formed on the terraces, which indicates that the terrace width has already been saturated. Therefore, the terrace width is mainly determined by the diffusion length of the adatom. The average number of steps in the bunch increases with the Ge concentration because the diffusion length increases with the Ge concentration. The diffusion length also increases with the temperature. So the higher the temperature is, the larger the step bunch becomes.