SIMULTANEOUS MOLECULAR-BEAM EPITAXY GROWTH AND SCANNING-TUNNELING-MICROSCOPY IMAGING DURING GE SI EPITAXY/

A high temperature scanning tunneling microscope (STM) capable of simu ltaneous imaging and molecular beam epitaxy (MBE) growth at 600-900 K sample temperature is described. The formation of the two-dimensional Stranski-Krastanov layer and the evolution of three-dimensional island s during further growth of Ge on Si (111) was observed. An inversion o f the aspect ratio of the islands with increasing coverage indicates a transition from coherent to dislocated 3D islands. This method (MBSTM ) opens the possibility to follow MBE growth processes with STM in a r eal in situ way and gives access to the evolution of specific features during growth.