Abstract
Resonance Raman spectra and absolute cross sections of InP/ZnSe/ZnS core/shell/shell nanocrystals have been obtained at excitation wavelengths of 501.7, 457.9, and 410 nm. Eight different structures having nearly the same lowest excitonic absorption wavelength but significantly different stoichiometries are compared. The Raman spectra show phonon features attributable to both the InP core and the ZnSe shell. The largest differences among the structures are seen in the ZnSe phonon region by using excitation at 457.9 nm, on the low-energy edge of the absorption features having significant contributions from the ZnSe shell. Here, structures that are nearly stoichiometric (In:P ratio ≈1.0) show a sharp, strongly polarized peak near the bulk ZnSe phonon frequency (μ250 cm-1) and a weak lower-frequency shoulder with a higher depolarization ratio. Structures having excess indium show a stronger low-frequency shoulder near 225 cm-1 and lower integrated Raman intensities throughout the ZnSe phonon region. These changes are attributed to the presence of indium atoms in the ZnSe shell. These results support a previous assignment of a slow rise component in the time-resolved photoluminescence spectra of nonstoichiometric structures to transient trapping of holes at indium defects in the shell.
Original language | English |
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Pages (from-to) | 10549-10557 |
Number of pages | 9 |
Journal | Journal of Physical Chemistry C |
Volume | 125 |
Issue number | 19 |
DOIs | |
State | Published - 20 May 2021 |
Externally published | Yes |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films