Elastic strain at the interface in Ge clusters on Si substrate—a Raman spectroscopic measurement

Ge clusters are grown on Si substrate at room temperature (Ge-RT) and also at liquid nitrogen temperature (Ge-LNT) by cluster evaporation technique. These clusters show blue luminescence. Raman measurement demonstrates the increase in strain with annealing in diffused disordered Si at the interface between Ge-LNT clusters and Si substrate. This manifests in strain-relaxation in the clusters as observed by Photoluminescence (PL) measurements. The decrease in PL intensity for Ge-RT with annealing has been attributed to reduction in surface oxide species, which is supported by Raman spectroscopic measurements. The objective of the paper is to understand the effect of thermal annealing on both interfacial strain and interdiffusion of elemental Si at the interface, together with luminescence characteristics of the clusters.