Charge states of vacancies in germanium investigated by simultaneous observation of germanium self-diffusion and arsenic diffusion

Diffusion of germanium (Ge) and arsenic (As) has been investigated simultaneously using As-implanted Ge isotope superlattices. No transient enhanced diffusion of As that could have arisen by the implantation damage is observed. A quadratic dependence of the Ge self-diffusion on the carrier concentration due to the Fermi level effect is observed. A precise reproduction of the Ge and As diffusion profiles by a numerical simulator lets us conclude that doubly negatively charged vacancies are the dominant point defects responsible for more than 95% of the self-diffusion in intrinsic Ge and this fraction increases even further in n-type Ge.