Lattice strain and static disorder in hydrogen-implanted and annealed single-crystal silicon as determined by large-angle convergent-beam electron diffraction

Abstract

The large-angle convergent-beam electron-diffraction technique, available in a conventional transmission electron microscope, has been employed in order to characterize the defective layer present in heavily damaged high-dose hydrogen-implanted and low-temperature annealed $(T<~500\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})$ single-crystal silicon in terms of lattice strain and static disorder. These quantities have been measured to determine the mean relaxation volume and atomic concentration of defect clusters present in the implanted layers in order to investigate the structural features causing the reverse annealing phenomena observed in ion channeling measurements. In particular, the mean relaxation volume detected in the 300 \ifmmode^\circ\else\textdegree\fi{}C 2-h annealed sample (0.1 ${\mathrm{nm}}^{3}$) results in a factor three times higher than that measured in the as-implanted sample; on the contrary the mean atomic concentration of clusters does not vary appreciably after this thermal treatment. This experimental evidence suggests a nonconservative growth of clusters in the low-temperature annealing regime. After annealing at 500 \ifmmode^\circ\else\textdegree\fi{}C for 2h, an increase of the relaxation volume and a significant decrease of the mean concentration is found, thus suggesting that only after this thermal treatment, producing in the meantime intrinsic defects with extended internal surfaces, defects seem to follow a conservative ripening.