Qualitative Analysis of the Presence of Ge Nanoclusters Embedded in SiO <i> _<i>x</i> </i> Matrix Using UV–Vis and EDX Spectroscopy

ABSTRACT The detection and characterization of embedded nanostructures in dielectric matrices pose significant challenges due to their subsurface nature and nanoscale dimensions. In this study, we are proposing a nondestructive alternative to investigate the distribution of germanium nanoclusters (Ge NCs) embedded in a SiO x matrix, using UV–visible diffuse reflectance spectroscopy (UV‐DRS) and energy‐dispersive X‐ray spectroscopy (EDX). Ge ions (15 keV) have been implanted at three fluences (2.5 × 10 15 , 5 × 10 15 , and 1 × 10 16 ions/cm 2 ) into the SiO x layer, followed by annealing at 800°C. UV‐DRS spectra in the 300‐ to 400‐nm range reveal changing position and intensity of the reflectance peaks with varying fluence, indicative of quantum confinement and matrix effect. In the case of the highest fluence, the specimen exhibits a nonmonotonic red shift accompanied by a reduction in the reflectance intensity, which has been ascribed to substantial strain induced around the Ge NCs, leading to modifications in the effective refractive index of the system. These optical changes were supported by transmission electron microscopy, which shows an increase in the NCs' density with fluence. At an optimum electron energy of 10 keV, EDX spectral images have been acquired. The spectral imaging results indicate a progressive increase in the concentration of Ge NCs with respect to the increase in fluence. In a nutshell, this study demonstrates that UV–Vis and EDX spectroscopies together serve as simple, effective, and nondestructive tools for the qualitative assessment of embedded NCs. These findings are relevant for designing optoelectronic materials where controlled NCs' growth is essential.