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 differ ent lattice constants will be discussed. It is demonstrated that an ep itaxial 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 stra in transfer model can explain recent experiments on the growth of low dislocation relaxed SiGe material on Si. For GaAs-based materials we p ropose a scheme to form a thin buffer by GaAs situated on top of a bur ied oxide such as Al2O3 through wet oxidation of AlAs. This GaAs thin buffer provides a flexible substrate for the growth of epifilms with t hicknesses not limited by conventional critical thickness for strained layers. Detailed numerical analysis on the growth of InxGa1-xAs on Ga As is also performed.