Effect of growth conditions on the structural properties of ion beam sputter deposited SiGe epilayers

Abstract

Structural properties of Si1−xGex layers epitaxially grown on Si(100) by Ion Beam Sputter Deposition were studied as a function of growth temperature and film thickness. It was shown that the structure of defects strongly depends on the growth temperature, Tg. The dislocations cross grid which is observed at the SiGe/Si interface for layers grown at high (700 °C) Tg is missing in layers grown at low (≲550 °C) Tg, while a new type of defects parallel to {001} and {113} lattice planes appear at these temperatures. The optimal Tg for a Ge content of 20-25 at. % was found to be close to 550-625 °C. Surface roughness for all the growth temperatures was found to be less than that for such a ‘‘smooth’’ technique as MBE. Photoluminescence studies revealed, to the best of our knowledge for the 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 these peaks is strongly correlated with the dynamics of strain relaxation and can be attributed to a set of dislocations at the SiGe/Si interface extending both to the epilayer and to the bulk Si.

Morphology, Defect Spectrum, and Photoluminescence of Thin Si[sub 0.7]Ge[sub 0.3] Layers

“…We have identified it as the D 2 peak. 19 On these figures and in the text we employ the subscripted notations to denote PL lines with photon energy of 0.82-0.85 eV. This allows one to distinguish them from the similar traditional notations for the hole trap levels, applied in the previous subsection.…”