Strain transfer between thin films on buried oxide and its application in heteroepitaxial crystal growth

A strain transfer process between two epitaxial thin films with different lattice constants will be discussed. It is demonstrated that an epitaxial film (epifilm) grown on top of a thin buffer layer may release the strain to the buffer layer, leaving the epifilm dislocation free. A criterion to achieve this strain transfer is also derived. The strain transfer model can explain recent experiments on the growth of low dislocation relaxed SiGe material on Si. For GaAs-based materials we propose a scheme to form a thin buffer by GaAs situated on top of a buried oxide such as Al₂O₃through wet oxidation of AlAs. This GaAs thin buffer provides a flexible substrate for the growth of epifilms with thicknesses not limited by conventional critical thickness for strained layers. Detailed numerical analysis on the growth of In_xGa_1-xAs on GaAs is also performed.