RAMAN SPECTROSCOPIC STUDIES ON ELASTIC STRAIN AT GERMANIUM PARTICLES-SILICON MATRIX INTERFACE

摘要

Germanium (Ge) clusters show luminescence at room temperature. The clusters are grown on Silicon (Si) substrate at room temperature (Ge-RT) and also at liquid nitrogen temperature (Ge-LNT) by cluster evaporation technique. Ge nanoparticles on glass substrates have been characterized by X-ray diffraction (XRD) measurements. The XRD pattern shows that Ge-LNT is not of diamond structure, as in bulk, but is tetragonal. 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. Raman measurement demonstrates the increase in strain with annealing in diffused disordered Si at the interface between Ge-LNT clusters and Si substrate. 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.