CHARACTERIZATION OF SI SI1-YCY SUPERLATTICES GROWN BY SURFACTANT ASSISTED MOLECULAR-BEAM EPITAXY/

Si/Si0.97C0.03 superlattices grown on Si(001) substrates by Sb surfact ant assisted molecular beam epitaxy are characterized by in situ refle ction high energy electron diffraction (RHEED), atomic force microscop y, transmission electron microscopy (TEM), and high resolution x-ray d iffraction. The RHEED shows that, in the absence of Sb, the growth fro nt roughens during Si0.97C0.03 growth and smooths during subsequent Si growth. In contrast, when Sb is present, the growth front remains smo oth throughout the growth. This observation is confirmed by cross-sect ional TEM, which reveals that for samples grown without the use of Sb, the Si/Si0.97C0.03 interfaces (Si0.97C0.03 on Si) are much more abrup t than the Si0.97C0.03/Si interfaces. In the case of Sb assisted growt h, there is no observable difference in abruptness between the two typ es of interfaces. Atomic force microscopy micrographs of the Si0.97C0. 03 surface reveal features that could be the source of the roughness o bserved by RHEED and TEM. (C) 1996 American Vacuum Society.