Self-organized MBE growth of Ge-rich SiGe dots on Si(100)

Si1-xGex dots with high Ge contents ranging from x = 0.4 to x = 1 were grown on Si(100) substrates with varying layer thickness. The structural examination of the dots, using atomic force microscopy, shows SiGe dots with lateral sizes between 100 and 200 nm and heights ranging from 8 to 30 nm. A reduction of the nominal layer thickness to the critical thickness for dot formation leads to an abrupt growth-mode changeover from three-dimensional island growth to two-dimensional layer growth. Strong evidence of Ge surface diffusion playing an important role in the formation of the dots is found.