Arsenic diffusion in boron-doped germanium

Arsenic (As) diffusion in germanium (Ge) has been studied by implanting As in a Ge substrate with high boron (B) background doping. The high hole density induced by the B doping suppresses negatively charged vacancies (V) in Ge. Under this condition, we have investigated the dependence of As diffusion on the dopant-vacancy pairs As⁺V⁰ by secondary ion mass spectroscopy. After rapid thermal annealing at 600-750-C, the chemical profiles of As do not change in the highly B doped Ge. Experimental results suggest that the As⁺V⁰ pairs are not the diffusion vehicles of As in Ge. Activation energy of the As⁺V⁰ pairs has to be larger than 3.25 eV.