Fluorescence spectroscopy characterization of cadmium sulfide quantum dots on metal, insulator, and semiconductor substrates

Colliodal cadmium sulfide quantum dots (Q-CdS), ranging in size from 1 to 5 nm and capped with dioctyl sulfosuccinate (AOT), were synthesized and deposited upon substrates of gold (Au), mica, and gallium arsenide (GaAs). Fluorescence spectroscopy is used to identify the range and maxima of excitation and emission spectra of each structure. A red shift in emission spectra from the Au to mica to GaAs substrate based samples is observed for the smallest-sized quantum dots. The midrange and largest-sized dots display the longest emission wavelengths when physisorbed to the Au substrates with a shift to shorter and then longer emission wavelengths for the mica and GaAs-based samples, respectively. The display of emission spectra throughout the visible range for the Q-CdS deposited on all three types of substrates bodes well for future optical device applications using hybrid (organic-inorganic) electronic materials. © 2011 Wiley Periodicals, Inc.