AFM images of (a) QV1, (b) QV2, and (c) QR. The inset shows the surface morphology of the ring, which gives an outer diameter of , a height of , and an inner diameter of 30 nm.
XTEM image of QR.
(a) Continuous wave PL spectra of QD, QV1, QV2, and QR. (b) Excitation density dependence of PL from QR sample.
Temperature dependence of PL transients from to 300 K at ground state energy of (a) QD, (b) QV1, (c) QV2, and (d) QR.
Temperature dependence of the PL decay time of QD, QV1, QV2, and QR samples and the fitting result of the two-band model.
Temperature dependence of PL transients from to 300 K at the first excited state energy of (a) QV1, (b) QV2, and (c) QR.
Calculated electron energy levels in QD, QV, and QR by solving the one band energy-dependent effective mass equation.
PL excitation spectra of QD (upper curve) and QR (lower curve) above the first excited state. The detection energy is fixed at the center of ground state energy.
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