Abstract
Interdiffusion at the interfaces of a multilayer structure consisting of 3 Ge layers of about 2.2, 4.3 and 2.2 nm thickness in a Si matrix was studied by depth profiling with AES. Measured depth profiles of the as deposited structure (grown at 300°C), taking the Ge LMM peak intensity as a function of the sputtering time, were compared with those obtained after annealing of the sample at 600, 650, and 700°C after quantitative evaluation with the MRI (mixing-roughness-information depth)-model. As a result, the interdiffusion constant was determined (Deff=6.3 E-22 m2/s at 973 K) as well as the activation energy (E≅0.9 eV). These values are considerably lower than the bulk diffusion coefficients. This effect presumably is connected with the strain in thin film multilayer Si/Ge heterostructures due to the lattice mismatch. It is especially important at low temperature annealing and has to be taken into account in the fabrication technology of of Si/Ge nanostructures.
