The atomic compositions of the films were detected by Rutherford

The atomic compositions of the films were detected by Rutherford backscattering analysis using 2.02 MeV 4He ion selleckchem beam at a scattering angle of 165°. The Si excess (N Si-ex) in this work can be calculated as N Si-ex = (N SRO − N SiO2)/N SiO2, where N SRO and N SiO2 stand for the atomic percentage of Si atoms in SRO matrix and that in the SiO2 matrix, respectively. After the deposition of films, a thermal annealing procedure at 1,100°C for 1 h in a quartz furnace under the nitrogen ambient was performed to separate Si NCs and to activate Er ions. The structural characteristics of the films were studied by high-resolution transmission electron microscopy (HRTEM; Tecnai G2 F20 S-Twin microscope (FEI, Eindhoven, Netherlands))

cross-sectional images. Room temperature photoluminescence (PL) was measured at the same test conditions using He-Cd laser with the excitation wavelength of 325 nm and detected by charge-coupled device (PIXIS:100BR, Princeton Instruments, Trenton, America) or photomultiplier tube (Hamamatsu R5509-72, Hamamatsu

Photonics K.K., Hamamatsu, Japan). For the time-resolved PL detected by a multichannel photon counting system (Edinburg Photonics, Livingston, UK), the see more samples were excited by a microsecond lamp with 325-nm line, and the overall time resolution of the system was about 2 μs. Results and discussion The influence of Si excess on the microstructures of Si NCs in SROEr films is studied using HRTEM, as shown in Figure 1. It can be seen that the Ceramide glucosyltransferase size of Si NCs increases slightly from 2 to 5 nm in the films with the Si excess from 11% to 88%. The density of Si NCs (indicated by white arrows) is similar to each other in all these films (on the order of 1012 cm−2) except for that with the Si excess of

11%. Si NCs in the film with the Si excess of 11% exhibit much smaller sizes, which is under the resolution of the HRTEM. In this work, we assume that the Si NCs density is similar and has an insignificant influence on the luminescent property of the films. Furthermore, no Er3+ clusters are found in all the films so that the quenching phenomenon caused by Er3+ clustering could also be disregarded [15]. Interestingly, Si NCs are separately embedded in the matrix with lower Si excess, as shown in the inset of Figure 1a,b. In contrast, the coalescence of neighboring Si NCs is found in the films with higher Si excess (Figure 1c,d), which are caused by an asymptotic ripening process [16]. Figure 1 HRTEM images of the SROEr films with different Si excesses. (a) 11%, (b) 36%, (c) 58%, and (d) 88%. The Si NCs are indicated by white arrows. The insets display the HRTEM images of Si NCs in the SROEr films. The coalescent Si NCs can be formed in the SROEr films with high Si excess. For the investigation of these Si NCs microstructural differences on the luminescence performance of the films, the PL spectra of the SRO and SROEr films with different Si excesses are provided, as shown in Figure 2.

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