EFFECT OF GROWTH-CONDITIONS ON THE STRUCTURAL-PROPERTIES OF ION-BEAM SPUTTER-DEPOSITED SIGE EPILAYERS

Structural properties of Si1-xGex layers epitaxially grown on Si(100) by Ion Beam Sputter Deposition were studied as a function of growth te mperature and film thickness. It was shown that the structure of defec ts strongly depends on the growth temperature, T-g. The dislocations c ross grid which is observed at the SiGe/Si interface for layers grown at high (700 degrees C) T-g is missing in layers grown at low (less th an or similar to 550 degrees C) T-g while a new type of defects parall el to {001} and {113} lattice planes appear at these temperatures. The optimal T-g for a Ge content of 20-25 at. % was found to be close to 550-625 degrees C. Surface roughness for all the growth temperatures w as found to be less than that for such a ''smooth'' technique as MBE. Photoluminescence studies revealed, to the best of our knowledge for t he first time, two peaks on the low energy side in the neighborhood of the Si(TO) peak of the epilayers. The evolution of the intensity of t hese peaks is strongly correlated with the dynamics of strain relaxati on and can be attributed to a set of dislocations at the SiGe/Si inter face extending both to the epilayer and to the bulk Si. (C) 1995 Ameri can Institute of Physics.