Field emitters for the development of a miniature ion trap mass spectrometer were discussed. The spectrometer was to be deployed aboard European Space Agency's Rosetta Mission for analyzing comet P46/Wirtanen. The instrument is < 75g in weight with a 1 W maximum power consumption and resolution down to < 1 amu. A number of gases were analyzed using mass spectrometry in the region of 10^-4 Torr.

S. E. Huq;B. J. Kent;R. Stevens;R. A. Lawes;宁生 许;峻聪 佘

Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures

2001-5

The high-temperature (over 1020 °C) polymorph of ZnS, wurtzite ZnS, has been successfully prepared through a low-temperature (180 °C) hydrothermal synthesis route in the presence of ethylenediamine (en). The effects of en concentrations, reactant concentrations, reaction temperatures, and reaction times on crystal structures and shapes of ZnS have been investigated. We have demonstrated that the wurtzite ZnS showing rodlike morphology can be kinetically stabilized in the presence of en, especially at a high reactant concentration under appropriate hydrothermal conditions. Besides phase evolution of ZnS from hexagonal to cubic, morphological transformation from nanorods to nanograins has also been observed in the present investigation. Nanograins of phase-pure cubic ZnS, the thermodynamically stable polymorph, are easily prepared, and no hexagonal ZnS nanorods are detected in "pure" water, i.e., in the absence of en molecules. The above investigations indicate that the controlled fabrication of wurtzite ZnS nanorods is due to a mediated generation of the lamellar phase, ZnS·0.5en, a covalent organic-inorganic network based on ZnS slabs, and to its subsequent thermolysis in aqueous solution. The controlled growth of wurtzite ZnS nanorods and sphalerite ZnS nanograins provides us an opportunity to structurally modulate physical properties. These wurtzite ZnS nanorods display narrower and stronger blue emission than sphalerite ZnS nanograins.

Xijian Chen;Huifang Xu;宁生 许;Fenghua Zhao;Wenjiao Lin;岗 林;Yunlong Fu;振立 黄;Hezhou Wang;明娒 吴

Inorganic Chemistry

2003-5-5

Large-area tungsten oxide nanorod arrays were synthesized by the catalyst-free tungsten hot-filament thermal vapor method. The diameter, height, interval and alignment of the nanorods were all found to be sensitive to the distance between hot filament and substrates. And the field emission property of the nanorod arrays prepared at various distances was shown to be significantly different. This demonstrates that optimal conditions can be found for preparing W₁₈O₄₉ nanorod arrays of better field emission property.

L. F. Chi;少芝 邓;宁生 许;军 陈;峻聪 佘;X. H. Liang

Journal of Physics: Conference Series

2009

Three-dimensional (3D) tungsten oxide nanowire networks have been demonstrated as a high-surface area material for building ultrasensitive and highly selective gas sensors. Utilizing the 3D hierarchical structure of the networks, high sensitivity has been obtained towards N O2, revealing the capability of the material to detect concentration as low as 50 ppb (parts per billion). The distinctive selectivity at different working temperatures is observed for various gases. The results highlight that the nanobelts (nanowires) technology can be adopted for the development of gas sensors with performances suitable for practical applications.

Andrea Ponzoni;Elisabetta Comini;Giorgio Sberveglieri;Jun Zhou;少芝 邓;宁生 许;Yong Ding;俊 周

Applied Physics Letters

2006-5-15

Amorphous indium-gallium-zinc-oxide thin film transistor (a-IGZO TFT) with offset structure is fabricated for active-driving of ZnO nanowire field emitters. ZnO nanowire field emitters grown by thermal oxidation method is integrated with the a-IGZO TFT. The results proved that the growth process of ZnO nanowires is compatible with the a-IGZO TFT fabrication process.

Xiaojie Li;小明 陈;Zhipeng Zhang;Hai Ou;峻聪 佘;少芝 邓;宁生 许;军 陈

2016-8-24

Direct epitaxial crystalline silicon thin film (CSiTF) solar cells on low-cost silicon sheets from powder (SSP) ribbons have been prepared using rapid thermal chemical vapour deposition (CVD) growth. The characterisation of CSiTF solar cells was investigated by electron and spectrally resolved light beam induced current (EBIC and SR-LBIC, respectively). All EBIC measurements were performed on both the front-side surface as well as on the cross-section of CSiTF solar cells. The electrical recombination was detected by EBIC and compared with their morphologies. The results of EBIC scan show that recombination centres are situated at grain boundaries (GBs); higher the density of grain, higher the recombination activities (higher contrast). Recombination of different intensity (strong and weak) takes place at vertical GBs. Compared with the high recombination at GBs, the contrast in intragrain is low. The dark contrast of the GBs and intragrain defects is clearly reduced near the surface due to the passivation by hydrogen, which indicates that the minority carrier diffusion length decreases gradually with the depth perpendicular to the surface. The diffusion length was determined by SR-LBIC. The results show that the diffusion length distribution is quite inhomogeneous over the whole cell area. A maximum L_eff of about 25μm and mean values around 15μm are calculated for the best solar cell.

Z. C. Liang;H. Shen;宁生 许;S. Reber

Solar Energy Materials and Solar Cells

2003-10-31

Utilizing the coupled piezoelectric and semiconducting dual properties of ZnO, we demonstrate a piezoelectric field effect transistor (PE-FET) that is composed of a ZnO nanowire (NW) (or nanobelt) bridging across two Ohmic contacts, in which the source to drain current is controlled by the bending of the NW. A possible mechanism for the PE-FET is suggested to be associated with the carrier trapping effect and the creation of a charge depletion zone under elastic deformatioin. This PE-FET has been applied as a force/pressure sensor for measuring forces in the nanonewton range and even smaller with the use of smaller NWs. An almost linear relationship between the bending force and the conductance was found at small bending regions, demonstrating the principle of nanowire-based nanoforce and nanopressure sensors.

Xudong Wang;Jun Zhou;Jinhui Song;Jin Liu;宁生 许;俊 周

Nano Letters

2006-12

ZnO nanowires were fabricated on the amorphous diamond thin layer on silicon substrates using thermal chemical vapor transport and condensation (CVTC) without any metal catalysts. The remarkable enhancement of the field emission of the nanocomposites by ZnO nanowires covered amorphous diamond was found compared to that of the intrinsic amorphous diamond, suggesting the probability of decorating amorphous diamond by fabricating one-dimensional nanostructures on its surface, which could largely improve the field emission by modifying surface microstructures. Associated with surface chemical reactions, a vapor-solid mechanism of ZnO nanowires nucleation and growth on amorphous diamond was established.

玉华 杨;成新 王;B. Wang;宁生 许;国伟 杨

Chemical Physics Letters

2005-2-25

Large-area ZnO nanowire field emitter arrays have important applications in flat-panel displays, light sources, photodetectors and X-ray sources, where it is crucial to realize a high field emission current and current density over a large-area. In this paper, large-area ZnO nanowire arrays with various array spacings were prepared by the thermal oxidation technique from patterned Zn film arrays, and their field emission properties were studied. The results show that the Zn array density is related to the nanowire length and population density. A mechanism is proposed wherein the stress-induced process and mass transport process both play key roles in the growth. Herein, ZnO nanowire arrays in a 4.7 × 4.7 cm² area exhibited a sufficient quantity of emission sites and diminished field screening effect and a high current of 12.9 mA with a current density of 0.58 mA/cm². This work provides useful guidance for optimizing ZnO nanowires and enhancing field emission current performance for large-area ZnO nanowire field emission devices.

Libin Wang;Yangyang Zhao;Keshuang Zheng;峻聪 佘;少芝 邓;宁生 许;军 陈

Applied Surface Science

2019-8-1

Broadband light emission of different sized ZnO nanoparticles (17 nm to 300 nm) has been measured under picosecond laser excitation. Each spectrum consists of three Gaussian components including one emerging inside band-gap. Such inside band-gap band shows a clear dependence of the weighted intensity on the sizes of nanoparticles. Originated from our simplified one-dimensional (1D) model it has been qualitatively deduced that such size dependence match with the surface-state modified band structure. Additionally, a critical grain size as 110 nm for surface states recombination of ZnO nanoparticles has been found experimentally.

福利 赵;Xiaofang Wang;Pingbo Xie;宁生 许;至展 徐

2007