3D resonator based on luminescence enhanced by both polarized, size-dependent whispering gallery modes and Fabry-Pérot waveguide modes in individual ZnO micro- and nanonails

A 3D resonator based on both polarized, size-dependent whispering gallery (WG) modes and Fabry-Pérot (FP) waveguide modes has been achieved using individual ZnO micro- and nanonails. Monochromatic cathodoluminescence images of the ZnO micro- and nanonails show that enhanced luminescence intensity is focused on two regions, i.e., the profile and the center of the micro- and nanonails. The luminescence from the center region is attributed to the emission enhanced by 1D FP waveguide modes, and that from the hexagonal profile is attributed to the emission enhanced by both polarized, size-dependent 2D WG modes when an individual ZnO nanocolumn is regarded as an optical resonator. Theoretical calculations and computer simulations based on the finite element method (FEM) with perfectly matched layer (PML) boundary conditions are performed, and the corresponding results are close to the experimental phenomena.

Field emission properties and growth mechanism of In2O3 nanostructures

Four kinds of nanostructures, nanoneedles, nanohooks, nanorods, and nanotowers of In2O3, have been grown by the vapor transport process with Au catalysts or without any catalysts. The morphology and structure of the prepared nanostructures are determined on the basis of field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The growth direction of the In2O3 nanoneedles is along the [001], and those of the other three nanostructures are along the [100]. The growth mechanism of the nanoneedles is the vapor-liquid-solid (VLS), and those of the other three nanostructures are the vapor-solid (VS) processes. The field emission properties of four kinds of In2O3 nanostructures have been investigated. Among them, the nanoneedles have the best field emission properties with the lowest turn-on field of 4.9 V/μm and the threshold field of 12 V/μm due to possessing the smallest emitter tip radius and the weakest screening effect.

Synthesis of three-dimensional AlN–Si3N4 branched heterostructures and their photoluminescence properties

Three-dimensional AlN–Si₃N₄ branched heterostructures are synthesized via extended vapor–liquid–solid and vapor–solid growth of one-dimensional Si₃N₄ nanostructures and AlN nanocones successively.

Self-catalytic crystal growth, formation mechanism, and optical properties of indium tin oxide nanostructures

In-Sn-O nanostructures with rectangular cross-sectional rod-like, sword-like, and bowling pin-like morphologies were successfully synthesized through self-catalytic growth. Mixed metallic In and Sn powders were used as source materials, and no catalyst layer was pre-coated on the substrates. The distance between the substrate and the source materials affected the size of the Sn-rich alloy particles during crystal growth in a quartz tube. This caused In-Sn-O nanostructures with various morphologies to form. An X-ray photoelectron spectroscope and a transmittance electron microscope with an energy-dispersive X-ray spectrometer were used to investigate the elemental binding states and compositions of the as-synthesized nanostructures. The Sn doping and oxygen vacancies in the In2O3 crystals corresponded to the blue-green and yellow-orange emission bands of the nanostructures, respectively.