Soft-solution route to ZnO nanowall array with low threshold power density

Abstract

ZnO nanowall array (ZNWA) has been directionally grown on the buffer layer of ZnO nanoparticles dip-coated on Si-wafer under a soft solution process. Nanowalls on substrate are in most suitable shape and orientation not only as an optical trap but also as an optical waveguide due to their unique growth habit, V[011¯0]⪢V[0001]≈V[0001¯]. Consequently, the stimulated emission at 384 nm through nanowalls is generated by the threshold power density of only 25 kW/cm2. Such UV lasing properties are superior to those of previously reported ZnO nanorod arrays. Moreover, there is no green (defect) emission due to the mild procedure to synthesize ZNWA.

Perpendicular Orientation of Anisotropic Au‐Tipped CdS Nanorods at the Air/Water Interface

“…It is of interest to align such hybrid nanorod systems. Among the methods utilized for organizing NRs are slow evaporation of the solvent,[3a], dip[7b],[7c],‐ and spin‐coating, self assembly,,[9c], electrochemical deposition, and others . However, the level of orientation of the 2 and 3D structures obtained by these methods is often low and horizontally lying NR assemblies are typically obtained.…”

Lasing and laser-induced motion of zinc oxide nano-crystals irradiated by ultraviolet laser beam

“…The stimulated emission under the light excitation of a Ti: Sapphire laser (266 nm, 120 fs) from ZnO nanosheets grown by cathodic electrodeposition have been reported by F. Wang et al [20] In addition, E. S. Jang et al have reported that a laser oscillation was observed from ZnO nanosheets prepared by a solution process with a Nd:YAG laser (355 nm, 25 ps) as an excitation laser, and the oscillation mechanism of a WGM type phenomenon inside the nanosheet were suggested. [21] In our study, the laser oscillation from the single nanosheet prepared by a CVD method were observed as well, and it should be noted that the oscillation spectra in Fig. 6 (b) were obviously clearer than the above investigations despite a long pulse duration of used third-harmonic Nd:YAG laser (355nm, 5 ns), which would indicate that the nanosheets synthesized by a CVD method had an excellent crystallization.…”

Lasing characteristics from optically-pumped ZnO nanocrystals for ultraviolet laser diode

“…The stimulated emission under the light excitation with a Ti: Sapphire laser (266 nm, 120 fs) from ZnO nanosheets grown by cathodic electrodeposition have been reported by F. Wang et al [5] In addition, E. S. Jang et al have reported that a lasing was observed from ZnO nanosheets prepared by a solution process with a Nd:YAG laser (355 nm, 25 ps) as an excitation laser, and the oscillation mechanism of a WGM type phenomenon inside the nanosheet were suggested. [6] In our study, the lasing from the single nanosheet prepared by a CVD method were observed as well, and it should be noted that the oscillation spectra in Fig. 4 (b) showed obviously clearer mode-structure than the above investigations due to a detailed PL measurement and a long pulse duration of used third-harmonic Nd:YAG laser (355nm, 5 ns).…”

“…In addition, various lasing mechanisms such as whispering gallery mode (WGM) in a ZnO nanowire, [1,2] random lasing from ZnO nanoparticles, [3,4] lasing inside a ZnO nanosheet or a ZnO nanoplate. [5,6] These reports show that ZnO nanocrystals can be candidates for excellent UV laser mediums. However, the concrete lasing mechanisms from ZnO nanocrystals are still under discussion, and there are some major challenges to solve.…”