DEFECT LEVELS IN SILICON BOMBARDED WITH LIGHT-IONS

Defect levels produced by H+, D+ and He+ ion bombardment of silicon with different phosphorus doping and oxygen content have been investigated using deep-level transient spectroscopy. After He+ implantation only pure damage defect levels occur, whereas after H+ and D+ implantation additional hydrogen-related defects are observed. Defect profiles are generally much broader than theoretical distributions. For vacancy-related defect levels both the peak concentration and the halfwidth of the profiles depend only on the Fermi energy. The broadening which increases with decreasing doping level is explained by a model based on electric-field-enhanced diffusion of the vacancies out of the collision cascades. For the most prominent hydrogen-related defect, E(c)-0.30 eV, a mechanism for its formation has been deduced. This defect is tentatively identified as (H-V) pair.