Optical and magnetic characterization of transition metal ion doped ZnO microspheres synthesized via laser ablation in air
TL;DR: In this paper, the synthesis of transition metal doped (TM) ZnO micropsheres using doped znO sintered targets containing Mn 1% dopant was reported.
Abstract: We report the synthesis of transition metal doped (TM) ZnO micropsheres using doped ZnO sintered targets containing Mn 1% dopant. Transition metals are prospective materials for p type acceptor doping in ZnO. Structural and morphology study were conducted using XRD (X-ray diffraction), SEM and Raman spectroscopy. Room temperature Photoluminescence (PL) spectra of the fabricated ZnO microspheres were measured, at an excitation wavelength of 355 nm. In our study, smooth spherical shaped micro particles with different diameters ranging from ~1 to 3 μm were grown in different substrates by using a pulsed N 3+: YAG laser. SEM (Scanning Electron Microscopy) images show the presence of uniform smooth surfaced spheres. Raman scattering measurements from the synthesised samples at 532 nm wavelength excitation provide confirms the wurtzite structure of the fabricated undoped and TM doped ZnO microsphere. The doped microspheres exhibited UV whispering gallery modes (WGM) cavity lasing by optical pumping. Magnetic measurements from TM doped ZnO microparticles using vibrating sample magnetometer (VSM) are in progress.
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TL;DR: In this article, a simple laser ablation in air was used to grow the ZnO spherical microcrystals, and the authors obtained ultraviolet whispering gallery mode (WGM) lasing from the sphere under pulsed laser excitation.
Abstract: We have succeeded in growing the ZnO spherical microcrystals by a simple laser ablation in air, and we have obtained ultraviolet (UV) whispering-gallery-mode (WGM) lasing from the sphere under pulsed laser excitation. In this growth technique, a solid ZnO target is rapidly heated by laserinduced plasma, and melted target is splashed from the irradiated spot as droplets. Then, the droplets are crystallized into spherical shapes by the surface tension during the dropping process. This rapid melting and solidifying process may be effective for doping impurities into ZnO. In this study, we fabricated P-, Sb-, and Mg-doped ZnO microspheres, and investigated their structures and optical properties. A blue-shift of UV WGM lasing from Mg-doped ZnO microsphere was obtained, indicating that the band-gap engineering of ZnO microsphere grown by the simple ablation technique was achieved.
4 citations
TL;DR: In this paper, a simple laser ablation in the air was used to grow the ZnO microspheres by a simple beamforming, and they obtained UV whisperinggallery-mode (WGM) lasing from the sphere under pulsed laser excitation.
Abstract: We have succeeded in growing the ZnO microspheres by a simple laser ablation in the air, and we have obtained UV whispering-gallery-mode (WGM) lasing from the sphere under pulsed laser excitation. In this study, we observed resonances of WGM in visible region under cw laser pumping. In addition, possible refractive index of the ZnO microsphere was estimated from the WGM peaks. Furthermore, we obtained room-temperature electroluminescence from the ZnO microsphere/p-GaN heterojunction under forward bias.
3 citations
TL;DR: In this article, the authors established the technique of fabricating spherical semiconductor microcrystals with suitable diameters for whispering gallery mode (WGM) lasing, which does not require complex processing.
Abstract: We have been establishing the technique of fabricating spherical semiconductor microcrystals with suitable diameters for whispering gallery mode (WGM) lasing. Concretely, semiconductor microspheres were synthesized by ablating various semiconductor-sintered targets with focused pulsed laser at high fluences. In this report, dependences of fabricated zinc oxide (ZnO) microstructures on laser wavelengths were investigated. Lasing characteristics and photoluminescence of ZnO microspheres were determined, and photoluminescence of Sb-doped ZnO microspheres were determined. Additionally, it was also found that Sb-doped ZnO and aluminum nitride microspheres can be similarly synthesized. By developing this method, which does not require complex processing, it is expected that efforts in the application of WGM lasing are accelerated in many kinds of semiconductors.
3 citations
TL;DR: In this article, the authors succeeded in synthesizing antimony-doped ZnO microspheres by ablating a Sb sintered target containing 5 wt% of Sb with a Nd:YAG laser at a fluence of 25 J/cm 2 in air.
Abstract: We succeeded in synthesizing antimony (Sb)-doped ZnO microspheres by ablating a ZnO sintered target containing 5 wt% of Sb with a Nd:YAG laser at a fluence of 25 J/cm 2 in air. The well-spherical ZnO microcrystals with diameters of 1-20 μm were collected on a substrate which was put near the ablation spot. Most of the ZnO microspheres have a crystalline structure. In addition, Raman peak of the Sb-doped ZnO microspheres was shifted toward lower frequency side, indicating substitutional Sb 3+ at Zn antisite. Room-temperature photoluminescence properties of the microsphere were investigated under 325 nm He-Cd laser or 355 nm Nd:YAG laser excitation. An ultraviolet (UV) emission and lasing in whispering gallery mode were observed from the photoexcited microsphere.
2 citations