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(a)-(c) PL spectra of three aqueous solutions of SiC QDs obtained from electrochemical etching of bulk 3C-, 6H-, and 4H-SiC, respectively. The black lines give an eye guide of the variation of the PL maximum. (d) PL peak wavelength versus excitation wavelength.
(a)-(c) PLE spectra under different monitoring wavelengths. The black lines mark the positions of the three peaks. (d) PLE spectra monitored at 580 nm.
Time-resolved PL spectra excited at 280 nm and monitored at 420 (3C), 450 (6H), and 450 nm (4H). Each curve can be fit by using a triple exponential. The component lifetime and relative amplitude are summarized in Table I.
TEM images of the SiC QDs obtained from (a) 6H and (b) 4H samples. Each inset shows the high-resolution micrograph of a typical SiC particle whose lattice fringes correspond to (200) planes of 3C-SiC. (c) Schematic depicting hexagonal ↔ cubic polytypic transformation of the SiC QD on a potential energy vs. nuclear coordinate curve.
Lifetimes (τ) and relative amplitudes (R) of the three components in the time-resolved PL spectrum of each aqueous solution of SiC QDs stemming, respectively, from bulk 3C-, 6H-, and 4H-SiC.
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