Electrically active defects induced by hydrogen and helium implantations in Ge

It was found from an analysis of DLTS spectra that low doses (<5×1010 cm−2) of H and He ion implantations resulted in the introduction of damage similar to that observed after MeV electron irradiation. The Sb-vacancy complex was the dominant deep-level defect in the lightly implanted samples. After implantations with doses higher than 5×1010 cm−2 peaks due to more complex defects were observed in the DLTS spectra. Implantations with heavy (⩾5×1013 cm−2) doses of both H and He ions caused the formation of a sub-surface layer with a high (up to 1×1017 cm−3) concentration of donors. These donors were eliminated by anneals at temperatures in the range 100-200 °C. Heat treatments of the heavy proton-implanted Ge samples in the temperature range 250-300 °C resulted in the formation of shallow hydrogen-related donors, the concentration of which was the highest in a region close to the projected depth of implanted protons. The maximum peak concentration of the H-related donors was higher than 1×1015 cm−3 for a proton implantation dose of 1×1014 cm−2.