Rongguo Xie

Phonon characteristics and cathodolumininescence of boron nitride nanotubes

Large quantities of highly pure boron nitride nanotubes (BNNTs) are synthesized through a carbon-free method. Nanotube phonon features are investigated by Raman and Fourier-transformed infrared spectroscopies. Both methods indicate highly pure boron nitride phase. Intense ultraviolet light emission is observed when BNNTs are excited by an electron beam, which indicates that the present BNNTs have potential applications in ultraviolet optical devices.

Enhancement and patterning of ultraviolet emission in ZnO with an electron beam

An intense enhancement of ultraviolet (UV) emission was observed in various kinds of ZnO samples that were prepared using a wet chemical method when they were under electron-beam irradiation. The UV emission can increase to more than two times its initial value, whereas the visible emission reduces to a negligible value. We suggest that this enhancement effect mainly results from electron-stimulated desorption of adsorbed water. Applying this effect, we have developed a simple technique of directly writing submicrometer UV emission patterns in ZnO with an electron beam without changing the material’s surface morphology.

Large-scale fabrication of boron nitride nanohorn

Boron nitride nanohorns (BNNHs) are synthesized in large scale. Their morphology and structure were investigated by scanning electron microscopy and transmission electron microscopy. The hollow conical structure and particular aggregation behavior are revealed. Cathodoluminescence measurement is performed and ultraviolet light emission is observed, which indicates the potential applications of BNNHs in optical devices.

Thermal-desorption induced enhancement and patterning of ultraviolet emission in chemically grown ZnO

A significant enhancement of ultraviolet (UV) emission has been observed in chemically grown ZnO samples using a thermal treatment at 200 °C. The intensity of UV emission can reach up to fifty times its initial value, while that of the visible emission decreases to a negligible value. Based on the thermal desorption spectroscopy results, the origin of this effect was attributed to the reduction of non-irradiative centres and hydrogen passivation through desorption of adsorbed water and hydroxyl groups. By precisely controlling the local desorption in ZnO with an electron beam, we have not only created optical nanotags on individual ZnO nanorods, but have also written sub-micrometre UV-emission patterns on ZnO films. It is believed that this patterning technique will extend the applications of ZnO to many other fields, such as high-density optical data storage and high-resolution UV-emission displays.

Synthesis and optical study of crystalline GaP nanoflowers

GaP nanoflowers composed of numerous GaP nanowires are synthesized through heating InP and Ga2O3 powders. Crystalline GaP nanowires growing from Ga-rich particles have a cubic structure, uniform diameters of ∼300nm, and lengths from several to tens of micrometers. Typically, an individual GaP nanowire displays a hexagonal prism-like morphology with ⟨111⟩ as the preferential growth direction. Cathodoluminescence measurements show that GaP nanoflowers and GaP nanowires emit at ∼600 and ∼750nm, respectively. Additional low-intensity emission peaks are observed for GaP nanoflowers at ∼450nm.GaP nanoflowers composed of numerous GaP nanowires are synthesized through heating InP and Ga2O3 powders. Crystalline GaP nanowires growing from Ga-rich particles have a cubic structure, uniform diameters of ∼300nm, and lengths from several to tens of micrometers. Typically, an individual GaP nanowire displays a hexagonal prism-like morphology with ⟨111⟩ as the preferential growth direction. Cathodoluminescence measurements show that GaP nanoflowers and GaP nanowires emit at ∼600 and ∼750nm, respectively. Additional low-intensity emission peaks are observed for GaP nanoflowers at ∼450nm.