CLEANING OF SI(100) SURFACE BY AS IONIZED CLUSTER BEAM PRIOR TO EPITAXIAL-GROWTH OF GAAS

It has been found that the exposure of a Si (100) surface to an As ionized cluster beam (ICB) is effective in the preparation of the surface prior to epitaxial growth of GaAs under conventional high vacuum conditions of 2 X 10(-5) Pa. This process is achieved at a temperature as low as 600-degrees-C. A clear 1 X 2 or 2 X 2 reflection high energy electron diffraction pattern observed after the procedure indicates good ordering of the sample surface. The cleaning process is attributed to chemical and physical sputtering by As ICB in the first stage and to the subsequent As termination of Si dangling bonds. It has been found that the optimum preparation conditions are an accelerating voltage of the As ionized cluster beam of 1.3 kV and a substrate temperature of 600-degrees-C. GaAs films deposited on As ICB treated Si (100) substrates show good crystal quality with single domain structure.