Comparison of various core electron treatments for studying the properties of II-VI quantum dots and their bulk counterparts: a DFT study

Abstract

Quantum dots (QDs) have attracted significant interest because of their tunable bandgaps, which enable numerous applications in fields such as photovoltaics, biomedicine, and materials science. This study explores various core electron treatments in the density functional theory (DFT) analysis of II-VI semiconductor quantum dots and their bulk counterparts. We compared All-electron (AE), Effective Core Potential (ECP), All-Electron Relativistic (AER), and DFT-Semicore pseudopotential (DSPP) treatments. Our findings indicate that the AE treatment aligns closely with the experimental results for smaller QDs, whereas the accuracy of DSPP increases with larger QDs. DSPP provides an optimal balance between computational efficiency and accuracy, making it suitable for studying II-VI QDs. Notably, the bandgap behavior varies, being direct for zinc and cadmium chalcogenides, whereas mercury chalcogenides are zero-gap semiconductors (semimetals). The inner bonds of the QDs exhibit an ionic character, whereas the terminal bonds display a covalent character. This study enhances our understanding of the structural and electronic properties of II-VI quantum QDs, aiding their application in various technologies.