RELAXED EPITAXIAL SI(1-X)GE-X GROWN BY MBE

MBE-grown, relaxed epitaxial Si1-xGex alloy layers with x=0.4 and 0.5 were studied by transmission electron microscopy (TEM), photoluminesce nce, atomic force microscopy (AFM) and channeling. The TEM studies did not reveal any extended defects in the layers, except for threading d islocations of a density less than or equal to 10(6) cm(-2). Strong ne ar-band luminescence due to bound excitons indicates a high quality of the films. Preferential chemical etching combined with AFM allowed us to detect the density of threading dislocations, which was estimated to be similar to 10(6) cm(-2) for x = 0.4 and 0.5. A deviation from pe rfect crystallinity was observed by channeling. The channeling paramet ers were measured as a function of depth by removal of thin layers by polishing; no depth dependence of the channeling parameters was detect ed.