The spontaneous formation of so-called self-assembled quantum dots (SAQDs) during heteroepitaxial growth has attracted much recent interest because of potential device applications. Much attention has been directed towards the Ge/Si(001) system, in particular to characterize the island shape and size distributions as a function of growth conditions, i.e., Ge coverage and substrate temperature. Due to the lattice mismatch, a layer-to-island transition occurs at coverages greater than about 3 monolayers, and thereafter small, coherent hut clusters and larger coherent and incoherent dome clusters are observed. Interdiffusion of Si into the Ge islands as a strain-relief mechanism also occurs. Strategies for achieving better control of island size, shape, composition and separation continue to be sought. in this paper, we report a preliminary investigation of island growth in the alternative Ge/Si(l12) system.
The Ge/Si(112) samples were grown by molecular beam epitaxy using a Riber 2300 system equipped with a Ge Knudsen effusion cell.