Kinetic formation and optical properties of self-assembled Ge/Si hut clusters

Structural and optical characterizations via reflection high-energy electron diffraction, atomic force microscopy and photoluminescence spectroscopy have been combined to investigate the kinetic formation of self-assembled Ge/Si hut clusters grown by ultra-high-vacuum chemical-vapor deposition. We show that point defects that are induced in the Ge and/or Si epilayers grown at low substrate temperatures greatly influence the optical properties of Ge/Si hut clusters. By undertaking controlled annealing experiments, in particular by rapid annealing up to a temperature of 900 °C for a very short period of time, we show that it is possible to 'repair' those defects, giving rise to the observation of the proper photoluminescence of hut clusters while Ge/Si intermixing is minimized.