Alternating layers of vacancy-type and interstitial-type defects in Ge ion implanted silicon

The defect structure of Ge-implanted and annealed silicon was investigated. Based on the observation of both, interstitial- and vacancy-type defects, a stacked structure of layers of vacancy and interstitial clusters was detected. These defects form a substructure within the basic dual structure consisting of a vacancy-dominated and an interstitial-dominated region. The appearance of cavities (vacancy clusters) in the interstitial-dominated region indicates significant vacancy–vacancy clustering beside the vacancy–interstitial recombination. Clustering of vacancies and interstitials prevents the vacancy–interstitial recombination. The observed defect structure is in contrast to the widely accepted +1 model which predicts the complete recombination of ion-generated vacancies and interstitials. The limits of the +1 model are discussed.