All the testing processes have been performed at room temperature and subsequently annealed at 900°C in N2 and O2 to optically activate the erbium. Compared with bulk silica, the PL of silica nanowires reveals stronger intensity and longer lifetime. The PL intensity of bulk silica increased after ion implantation, but it decreased with the augmentation of implantation fluence. After ion implantation, the

PL lifetime of the material decreased. This behavior is attributed to concentration quenching caused by ion implantation [47]. The concentration of nonradiative defects will increase during the implantation process. All samples annealed in O2 have stronger PL intensity and longer lifetime than the samples annealed in N2. Annealing in the O2 atmosphere increases the concentration of Er3+ and reduces the oxygen-deficient defect centers in silica. The PL intensity of the material is related selleck inhibitor to the Er3+ concentration, and the PL lifetime is related to the concentration GSK3235025 cell line of nonradiative defects. Figure 9 Room-temperature PL measurements of bulk and NW samples as a function of ErO – implant fluence and ambience. (a) Integrated PL intensity and (b) luminescence decay rate (lifetime). Reprinted with permission from Elliman et al. [46]. In recent years, short wavelength laser has been widely researched. ZnO has high optical gain

and energy conversion efficiency excited by UV light at room temperature. The luminescence spectrum of ZnO has good monochromaticity. All these characteristics impel ZnO to be a tremendous prospect for optical device application. The ZnO NW-based optically pumped laser has already been realized by Zimmler et al. [48]. ZnO can realize multiband luminescence by doping with optically active elements; this property provides a possibility to fabricate various color optical devices. Müller et al. [49] researched the luminescence of transition metal-implanted ZnO nanowires. Figure 10 shows the cathodoluminescence spectra of Ni-, Fe-, Co- and Ar-implanted and as-grown ZnO

nanowires. In Figure 10, the as-grown nanowire PtdIns(3,4)P2 reveals a sharp UV luminescence. The cathodoluminescence of the ion-implanted nanowires is obviously different from that of the as-grown nanowire. After annealing, Ar diffused out of the lattice, and transition metal elements occupied the zinc HMPL-504 lattice site [50, 51]. The increasing interstitial zinc acts as a shallow donor. The concentration of the interstitial oxygen increased after annealing, and the interstitial oxygen is a deep acceptor. All the implanted samples show a structured green luminescence ascribing to the transition from the shallow donor to the deep acceptor. In the red luminescence region, Co- and Fe-implanted ZnO nanowires reveal an obvious intra-shell luminescence. Ronning et al. [52] reported the ZnO nanobelts implanted with 30-keV Mn+ ions; after annealing at 800°C, the structure and luminescence of ZnO nanobelts were recovered.