THE EFFECT OF ION IRRADIATION ON THE THERMAL-STABILITY OF GESI SI STRAINED-LAYER HETEROSTRUCTURES/

Double Crystal X-ray Diffraction (DCXRD), Transmission Electron Micros copy (TEM), and Rutherford Backscattering Spectrometry and Channelling (RBS-C) are used to study the effect of ion irradiation on the strain and strain relaxation of metastable GexSi1-x/Si strained layers, Room temperature irradiation within the alloy layer is shown to increase t he measured lattice strain, behaviour which is well modelled by assumi ng a strain profile which is based on the excess interstitial distribu tion created by the irradiation, During annealing to 650 degrees C the radiation damage evolves into intermediate defect complexes and dislo cation loops, and misfit dislocations nucleate and grow. The interacti ons between these different defects can result in a complex strain rel axation sequence which depends on the relative strain contributions of the defects and their relative nucleation and growth behaviour. Strai n relaxation can therefore be enhanced or retarded by the ion-irradiat ion depending on the irradiation fluence and annealing temperature. Ev olution of strain in irradiated GexSi1-x/Si alloy layers is discussed with reference to the defect microstructure after irradiation and anne aling.