Electronic structure and compositional interdiffusion in self-assembled Ge quantum dots on Si(001)

The radiative recombination peaks over a broad energy range of 0.75-0.9 eV have been observed by photoluminescence spectroscopy in self-assembled Ge/Si quantum dot structures. In order to clarify the broadness of the peak distribution, we have investigated the electronic structure of an approximate model by taking the profiles of strain components at atomic positions into account. The three-dimensionally confined levels are then obtained by diagonalizing the Hamiltonian matrix of the Schrodinger equation based on strain-modified potential. Theoretical results compared with the observed recombination energies verify that significant interdiffusion between a Si capping layer and a Ge dot takes place. This is also consistent with recently reported experimental results. (C) 2001 American Institute of Physics.