Diffusion and defect reactions between donors, C, and vacancies in Ge. I. Experimental results
Abstract
The diffusion of self-atoms and $n$-type dopants such as phosphorus, arsenic, and antimony in germanium was studied by means of isotopically controlled multilayer structures doped with carbon. The diffusion profiles reveal an aggregation of the dopants within the carbon-doped layers and a retarded penetration depth compared to dopant diffusion in high-purity natural Ge. Dopant aggregation and diffusion retardation are strongest for Sb and similar for P and As. In addition, the shape of the dopant profiles changes for dopant concentrations in the range of ${10}^{20}\text{ }{\text{cm}}^{\ensuremath{-}3}$ mainly due to the formation of dopant-vacancy complexes, which is more significant at high concentrations. Accurate modeling of the simultaneous self-diffusion and dopant diffusion is achieved on the basis of the vacancy mechanism and additional reactions that take into account the formation of neutral carbon-vacancy-dopant and neutral dopant-vacancy complexes. The stability of these complexes is compared to theoretical calculations published recently and to additional calculations presented in Part II. The overall consistency between the experimental and theoretical results supports the stabilization of donor-vacancy complexes in Ge by the presence of carbon and the dopant deactivation via the formation of dopant-vacancy and carbon-vacancy-dopant complexes.