Migration of Te atoms and structural changes in CdS/CdTe heterojuctions studied by x-ray scattering and fluorescence

Abstract

X-ray reflectivity and angular dependence of x-ray fluorescence ͑ADXRF͒ techniques have been employed for a quantitative study of the Te depth profile and structural changes in a series of CdS/CdTe heterojuctions annealed at various temperatures. The temperature dependence of surface roughening and Te migration is observed in both reflectivity and fluorescence experiments. Changes in the interface morphology and Te distribution are quantified by detailed analysis of the ADXRF data with the aid of reflectivity measurements. The results show that a large amount of Te up to 50% could migrate into the CdS layer and suggest that an extra layer of compounds can be formed near the CdS top surface. We have thus demonstrated that the x-ray reflectivity and ADXRF methods can be used as effective tools for nondestructive characterization of the concentration depth profile and interface morphology in layered structures on a nanometer scale.

The distribution of impurities in the interfaces and window layers of thin-film solar cells

“…4͑b͒ highlight the migration of Te from CdTe into the CdS layer following the CdCl 2 heat treatment, since the concentration of Te in CdS is slightly higher for the treated structure compared to the untreated one. Similar observations were reported by many authors, and, in particular, recently by Kim et al 15 The profiles of Na ͓Fig. 1͑a͔͒, S ͓Fig.…”

Phase Separation Inside the CdTe−CdSe Type II Quantum Dots Revealed by Synchrotron X-ray Diffraction and Scattering

“…Likely, the surface of CdSe nanoparticles might be less protected by the surfactants, when the coating with the CdTe shell layer was proceeded at the temperature of ∼473 K. This surfactant depleting effect at the temperature near the surfactant decomposition temperature of the CdSe NPs might have created an opportunity for cadmium and tellurium atoms to diffuse deeper into the CdSe nuclides. Similar temperature-dependent diffusion of Te into a CdS layer was also observed in a thin film system using X-ray reflectivity . Nevertheless, at this stage, the mechanism for the disappearance of the signature CdSe PXRD pattern in the CdSe-core-based QDs has not been resolved in detail.…”

“…Similar temperature-dependent diffusion of Te into a CdS layer was also observed in a thin film system using X-ray reflectivity. 28 Nevertheless, at this stage, the mechanism for the disappearance of the signature CdSe PXRD pattern in the CdSe-core-based QDs has not been resolved in detail.…”