STRAIN-STABILIZED HIGHLY CONCENTRATED PSEUDOMORPHIC SI1-XCX LAYERS INSI

We present evidence that Si1-xCx layers with x almost-equal-to 0.20 ca n be grown pseudomorphically on a Si(001) substrate despite the large difference of the C and Si lattice constants. Calculations based on de nsity-functional theory and a Keating model predict that embedded laye rs of certain structures with stoichiometry Sin-1C where n = 5,6,... a re considerably more stable than isolated C impurities. The common fea ture of these structures is that the carbon atoms tend to arrange as t hird-nearest neighbors. Multilayer structures grown by molecular beam epitaxy strongly suggest that defect-free heterostructures with such h igh C concentrations can be fabricated.