Fabrication of self-organised Ge dots using self-patterned SiGe template layer

This paper describes fabrication and optical properties of Ge nanostructures (dots or wires) grown on atomically controlled and self-patterned Si1−xGex template layers. All the difficulty of the process lies in the realization of the pre-patterned layer which is based on the kinetic development of a step-bunching instability. A comprehensive study on the influence of growth kinetics on morphological features of the Si1−xGex template layer is presented. It mainly concentrates on the quantification of correlation length (L), amplitude (A) and aspect ratio (A/L) of the profiles by atomic force microscopy (AFM) Fourier transform measurements. Results show the determinant role of annealing and interruption time on the dot stabilisation, aspect ratio and optical properties. Analysis of the surface profile evolution during the subsequent deposition of Ge on the template layer shows that Ge dots are fully located on the top of the Si1−xGex undulations. Finally we show enhanced optical properties for self-organised Ge dots deposited on the top of a self-patterned Si1−xGex template layer.