Evaluation of the dielectric function of colloidal Cd1 − xHgxTe quantum dot films by spectroscopic ellipsometry

Bejaoui, A. et al.We report on the investigation by spectroscopic ellipsometry of films containing Cd1 − xHgxTe alloy quantum dots (QDs). The alloy QDs were fabricated from colloidal CdTe QDs grown by an aqueous synthesis process followed by an ion-exchange step in which Hg2+ ions progressively replace Cd2+. For ellipsometric studies, several films were prepared on glass substrates using layer-by-layer (LBL) deposition. The contribution of the QDs to the measured ellipsometric spectra is extracted from a multi-sample, transmission and multi- angle-of-incidence ellipsometric data analysis fitted using standard multilayer and effective medium models that include surface roughness effects, modeled by an effective medium approximation. The relationship of the dielectric function of the QDs retrieved from these studies to that of the corresponding II–VI bulk material counterparts is presented and discussed.The authors acknowledge financial support from the RGC/CSIC Joint Research Scheme with Refs. S-HK001/12 (RGC) and 2011HK0016 (CSIC). MIA, MG, MCQ and ARG thank the Spanish Ministry of Economy and Competitiveness for funding through grant MAT2015-70850-P, and the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496). JAZ acknowledges partial support from Project CityU 122812 from the Research Grants Council of Hong Kong. SVK and ALR acknowledge support from the Research Grants Council of Hong Kong (project CityU 11302114), and from the CityU Research Project 9610350.Peer reviewe