Variation of ion-irradiation induced strain as a function of ion fluence in Si

Abstract

Strain in Si induced by ion irradiation at temperatures of 200–400°C has been measured at room temperature. Quantitative analysis of the strain distribution produced by 750-keV Si ion implantation in Si substrates was characterized by double-crystal X-ray diffraction (DCXRD). Strain in the Si surface layer was determined by modeling the DCXRD rocking curve using the program Rocking curve Analysis by Dynamic Simulation (RADS) where a generated strain profile is iteratively fitted to the measured rocking curve.The strain was tensile, resulting from a vacancy excess, and measured as a function of irradiation temperature and ion fluence. For a given temperature, strain increased as a function of ion fluence until a strain maximum was attained and then relaxed via dislocation formation. The maximum strain attainable decreased with an increase in irradiation temperature as consistent with thermally activated dislocation formation.