Sputtering and the annealing of radiation damage in single crystal semiconductors

Abstract

Single crystals of germanium, silicon and indium antimonide were bombarded with medium energy (5, 10, 15 keV) rare gas ions and the effects arising from the interaction of these ions with target atoms studied. Incidence of energetic ions in the crystal is followed by ejection of lattice atoms from their normal positions. The ejection of atoms from the bombarded surface was studied with two methods, namely the sputtered atom ejection pattern technique and monitoring of the sputtering yields using a mass spectrometrie technique. Ejection patterns were collected from (111) and (100) surfaces of silicon, (111), (110) and (100) surfaces of germanium and (ill), (110) and (100) surfaces of indium antimonide. The patterns were examined as functions of ion mass, ion energy, target temperature and species, and target orientation. Major ejection directions of target species were determined. In addition the ejection patterns from the elemental semiconductors were compared with those from compound semiconductors and significant differences were found. The results were analyzed on the basis of current models of anisotropic ejection from semiconductors. For quantitative evaluation of the sputtering process a mass spectrometric technique was developed. This technique, which is reported in detail, was employed in following the variation of relative sputtering yields with ion beam incidence direction as the target was rotated about the normal. Critical angles for channelling were determined from the data, and the results compared with the models of Onderdelinden (1968) and with the transparency model. In addition both techniques were used to study the production and insitu annealing of i o n bombardment induced damage. The rate of production was observed to depend on ion energy , ion mass, target species and orientation , target temperature and dose rate , Activation energies for the annealing processes were calculated . The thesis commences with a review of relevant experimental and theoretical aspects of ion -crystal interaction . Show more