title: Freestanding silicon quantum dots: origin of red and blue luminescence.
abstract: In this paper, we studied the behavior of silicon quantum dots (Si-QDs) after etching and surface oxidation by means of photoluminescence (PL) measurements, Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance spectroscopy (EPR). We observed that etching of red luminescing Si-QDs with HF acid drastically reduces the concentration of defects and significantly enhances their PL intensity together with a small shift in the emission spectrum. Additionally, we observed the emergence of blue luminescence from Si-QDs during the re-oxidation of freshly etched particles. Our results indicate that the red emission is related to the quantum confinement effect, while the blue emission from Si-QDs is related to defect states at the newly formed silicon oxide surface.
authors.affiliation: Institut für Verbrennung und Gasdynamik, Universität Duisburg-Essen, Duisburg, Germany.
authors.forename: Anoop
authors.initials: A
authors.lastname: Gupta
authors.forename: Hartmut
authors.initials: H
authors.lastname: Wiggers