Mechanism of the reduction of dislocation density in epilayers grown on compliant substrates

A simplified model of the mechanism of dislocation reduction in epilayers grown on compliant substrates by molecular-beam epitaxy has been developed based on the dislocation theory and detailed experiments. Theoretical results calculated with this model indicate that up to 100-fold defect reduction can be achieved by using a silicon-on-insulator compliant substrate for the thick epilayer growth as compared to that of using a conventional Si substrate. The advantage of growing thick epilayers on compliant substrates can be predicted quantitatively. The mechanism of a nearly dislocation-free SiGe alloy, as well as GaAs epilayers grown on silicon-on-insulator compliant substrates, is explained and the dislocation density calculated with this model is in good agreement with our experimental results.