DETERMINATION OF THE ACTIVATION-ENERGY FOR THE HETEROGENEOUS NUCLEATION OF MISFIT DISLOCATIONS IN SI1-XGEX SI DEPOSITED BY SELECTIVE EPITAXY/

Si0.84Ce0.16/Si heterostructures with variable finite lateral dimensio ns (10-300 mu m) and different layer thicknesses grown by selective lo w pressure chemical vapor deposition epitaxy at a temperature of 700 d egrees C were investigated with regard to relaxation by formation of m isfit dislocations. While in small structures only nucleation and prop agation occur, the dislocation-dislocation interaction (mainly multipl ication) becomes more and more important in larger structures. Therefo re it was possible to separate the three different mechanisms which pl ay a role in relaxation, i.e., nucleation, propagation, and multiplica tion, and to study them independently. From the analysis of the misfit dislocations at the initial stage of relaxation it was possible to de termine the nucleation site density and an activation energy of 2.8 eV for the heterogeneous nucleation of misfit dislocations. (C) 1997 Ame rican Institute of Physics.