Anomalous activation of shallow B+ implants in Ge

The electrical activation of B+ implantation at 2 keV to doses of 5.0 × 1013–5.0 × 1015 cm−2 in crystalline and pre-amorphized Ge following annealing at 400 °C for 1.0 h was studied using micro Hall effect measurements. Preamorphization improved activation for all samples with the samples implanted to a dose of 5.0 × 1015 cm−2 displaying an estimated maximum active B concentration of 4.0 × 1020 cm−3 as compared to 2.0 × 1020 cm−3 for the crystalline sample. However, incomplete activation was observed for all samples across the investigated dose range. For the sample implanted to a dose of 5.0 × 1013 cm−2, activation values were 7% and 30%, for c-Ge and PA-Ge, respectively. The results suggest the presence of an anomalous clustering phenomenon of shallow B+ implants in Ge.

► Electrical activation behavior of shallow B+ implants in Ge. ► Micro Hall effect results reported as a function of dose in crystalline and preamorphized Ge. ► Partial amorphization created by 2 keV 5 × 1015 B+/cm2 dose into crystalline Ge. ► Incomplete activation observed for all doses investigated. ► Evidence of B clustering for shallow implants in Ge.