Structural and optical characterizations via reflection high-energy electron diffraction and atomic force microscopy were combined to investigate the kinetic formation of self-assembled Ge/Si hut clusters grown at a substrate temperature of 525C by ultra-high vacuum chemical-vapor deposition. It was shown that point defects that were induced in the epilayers grown at such a low substrate temperature greatly influence the optical properties of Ge/Si hut clusters. An investigation was made of two approaches of sample annealing in order to remove point defects while minimizing Ge/Si intermixing: long annealing at the growth temperature and rapid annealing up to 900C for a very short period of time. The results obtained appear to indicate that the long annealing at the growth temperature may reduce the contribution of point defects, giving rise to the observation of the proper photoluminescence of the Ge/Si hut clusters. The rapid thermal annealing is, on the other hand, shown to be efficient for removing point defects but more controlled annealing, was probably needed in order to minimize the Ge/Si intermixing.

Role of Point Defects on the Optical Properties of Self-Assembled Ge/Si Hut Clusters. T.K.Nguyen-Duc, V.Le Thanh, L.H.Nguyen, P.Boucaud, V.Yam, D.Bouchier, F.A.d’Avitaya, J.Derrien: Journal of Crystal Growth, 2005, 275[1-2], e1287-94