(a) Scanning electron microscopy (SEM) picture of the ZnS nanowires. (b) Monochromatic cathodoluminescence image acquired at 546 nm (5 nm bandpass) showing the uniform intra 4f-emission of the Tb implanted ZnS (xTb = 4 × 10−3) nanowires.
EDX spectra of Tb implanted ZnS nanowires after annealing at 600 °C. The determined Tb content is xTb = 4 ± 2 × 10−2.
Spectrum of the integrated photoluminescence of ZnS nanowires doped with xMn = 3.2 × 10−4 (a) and xTb = 4 × 10−3 (b) respectively measured at 10 K with an excitation at 355 nm. The inset in (b) shows the integrated photoluminescence intensity around 550 nm for different Tb concentrations.
Transients of ZnS nanowires doped with different concentrations of Mn (a) and of Tb (b) measured at 10 K. Solid lines represent the fit with the modified Förster model using Eq. (1) .
Transients of the ZnS:Mn nanowires with a concentration of xMn = 4 × 10−5 taken at 10 K for different excitation densities. The solid lines are the corresponding fit curves of the modified Förster model with a decreasing “killer” center line density n for higher excitation densities. Other parameters were kept constant for all curves: R 0 = 4.85 nm, τMn = τMigr = 2 ms and d = 1.
Transients of the ZnS:Mn wires with a concentration of xMn = 4 × 10−5 taken at different temperatures with an excitation density of 4.6 mJ/cm2. The solid lines were fitted with the modified Förster model using a larger R 0 for higher temperatures. The other parameters were fixed for all curves: τMn = τMigr = 2 ms, n = 0.195 cm−1 and d = 1.
Images of Tb doped ZnS nanowires with a concentration of xTb = 4 × 10−3. (a) Picture of a micro-ensemble of wires taken with a TV CCD in reflection geometry. (b) Image of a single nanowire taken with the ICCD in the zero order of the spectrograph.
Transients of the Tb luminescence of a macroscopic ensemble (black squares), microscopic ensemble (red dots) and a single ZnS nanowire (green triangles) with a Tb concentration of xTb = 4 × 10−3 measured at room temperature. The solid line is a guide to the eyes only.
Fitting parameters used for the modified Förster model in Eq. (1) for doped ZnS nanowires with different concentrations. The other parameters have been kept constant: τMn/Tb = 2 ms; n = 0.26 nm−1.
Article metrics loading...
Full text loading...