Channeling analysis of stacking defects in epitaxial Si layers

Abstract

The channeling effect technique has been applied to investigate dechanneling by stacking defects in heteroepitaxially grown silicon. Ion backscattering was performed on 0.9 μm Si layers grown on sapphire as a function of beam energy (1.1–2.5 MeV He +), projectile ion (He +, D +) and crystal direction (〈100〉, 〈111〉, 〈112〉,〈113〉). Transmission electron muscopy analysis revealed the presence of a high density of stacking faults and twin lamellae. A model based on the new interior surfaces presented by such stacking defects is used to calculate the dechanneling cross section, and the disorder profiles are obtained from the experimental dechanneled fractions in terms of displaced rows per unit volume. Direct backscattering of channeled particles from the defects is neglected since the dechanneling cross section per row is about one order of magnitude larger than that per displaced atom. The resulting defect depth distributions are independent of beam energy and projectile ion, and give improved quantitative agreement with previous studies. The application of channeling to stackingdefect measurements requires a minimum density of ∼10 15 displaced rows/cm 2.