The formation of dislocations in the interface of GeSi/low-temperature Si buffer grown on Si (001)

We have studied the mechanism of strain relaxation of Ge0.3Si0.7 alloy laye rs grown on low-temperature (LT) Si buffers by high-resolution X-ray diffra ction and transmission electron microscopy (TEM). X-ray rocking-curve analy ses show that the strain relaxation of an alloy layer is quite inhomogeneou s at its early stage, and becomes homogeneous when the layer approaches bec omes fully relaxed. High-resolution cross-section TEM analyses indicate tha t stacking faults hale formed in the LT buffer near the interface of LT-Si/ GeSi and have separated the mismatch dislocations in the interface of GeSi/ LT-Si into Shockley partials. We propose that this could be due to the aggr egation of the vacant defects ill the LT-SI layer. The mechanism of this ag gregation is the osmotic force created by the vacancy super-saturation in t he LT-SI layer and/or the tension stress propagating from the interface of GeSi/LT-Si. (C) 2001 Elsevier Science B.V. All rights reserved.