Radiative recombination peaks, with energies ranging from 0.75 to 0.9eV, were observed by means of photoluminescence spectroscopy in self-assembled Ge/Si quantum dot structures. The electronic structure of an approximate model was investigated by taking the profiles of strain components into account. The 3-dimensionally confined levels were then obtained by diagonalizing the Hamiltonian matrix of the Schrödinger equation, based on a strain-modified potential. The theoretical results, when compared with the observed recombination energies, confirmed that significant interdiffusion took place between a Si capping layer and a Ge dot. This was consistent with recently reported experimental results.

Electronic Structure and Compositional Interdiffusion in Self-Assembled Ge Quantum Dots on Si(001). J.H.Seok, J.Y.Kim: Applied Physics Letters, 2001, 78[20], 3124-6