Effect of irradiation temperature on post-irradiation strain levels in Ge _xSi _1-x/Si strained layer heterostructures

Abstract

Double crystal x-ray diffraction (DCXRD), transmission electron microscopy (TEM), and Rutherford backscattering spectroscopy and channelling (RBS-C) were used to study the effect of irradiation temperature and ion-energy on the perpendicular strain (ε ⊥) in Ge xSi 1-xSi strained layer heterostructures. Room temperature irradiation was shown to increase ε ⊥. This effect was adequately modelled by assuming that irradiation caused additional strain due to excess interstitial distribution. The effects of irradiating at 253 °C were more complex, resulting in: a) an increase in ε ⊥ when the radiation damage profile was confined to the alloy layer; or b) a decrease in ε ⊥ when the damage profile extended through the alloy/substrate interface. Strain relaxation at elevated temperature is believed to be effected by loop-like defects which nucleate at or near the alloy/substrate interface during high energy irradiation. Show more