Optimizing Performance of Coaxis Planar-Gated ZnO Nanowire Field-Emitter Arrays by Tuning Pixel Density.

Gated ZnO nanowire field emitter arrays (FEAs) have important applications in large-area vacuum microelectronic devices such as flat panel X-ray sources and photodetectors. As the application requires high-pixel-density FEAs, how the pixel density affects the emission performance of the gated ZnO nanowire FEAs needs investigating. In this paper, the performance of coaxis planar -gated ZnO nanowire FEAs was simulated under different pixel sizes while keeping the lateral geometric parameter in proportion. The variations in emission current and gate modulation with pixel size were obtained. Using the obtained device parameters, the coaxis planar-gated ZnO nanowire FEAs were prepared. Field emission measurement results showed that a current density of 3.2 mA/cm2 was achieved from the fabricated ZnO nanowire FEAs when the gate voltage was 140 V. A transconductance of 253 nS was obtained, indicating effective gate control. The improved performance is attributed to optimized gate modulation.

Optimal Water Resources Regulation for the Pond Irrigation System Based on Simulation-A Case Study in Jiang-Huai Hilly Regions, China.

Due to the importance and complexity of water resources regulations in the pond irrigation systems of the Jiang-Huai hilly regions, a water allocation simulation model for pond irrigation districts based on system simulation theory was developed in this study. To maximize agricultural irrigation benefits while guaranteeing rural domestic water demand, an optimal water resources regulation model for pond irrigation districts and a simulation-based optimal water resources regulation technology system for the pond irrigation system were developed. Using this system, it was determined that the suitable pond coverage rate (pond capacity per unit area) was 2.92 × 105 m3/km2. Suitable water supply and operational rules for adjusting crop planting structure were also developed the water-saving irrigation method and irrigation system. To guarantee rural domestic water demand, the multi-year average total irrigation water deficit of the study area decreased by 4.66 × 104 m3/km2; the average multi-year water deficit ratio decreased from 20.40% to 1.18%; the average multi-year irrigation benefit increased by 1.11 × 105 RMB (16,128$)/km2; and the average multi-year revenue increased by 6.69%. Both the economic and social benefits were significant. The results of this study provide a theoretical basis and technological support for comprehensive pone governance in the Jiang-Huai hilly regions and promote the establishment of a water allocation scheme and irrigation system for pond irrigation districts, which have practical significance and important application value.

Coplanar-gate ZnO nanowire field emitter arrays with enhanced gate-control performance using a ring-shaped cathode.

Nanowire field emitters have great potential for use as large-area gated field emitter arrays (FEAs). However, the micrometer-scale cathode patterns in gated FEA devices will reduce regulation of the gate voltage and limit the field emission currents of these devices as a result of field-screening effect among the neighboring nanowires. In this article, a ring-shaped ZnO nanowire pad is proposed to overcome this problem. Diode measurements show that the prepared ring-shaped ZnO nanowire pad arrays shows uniform emission with a turn-on field of 5.9 V/µm and a field emission current density of 4.6 mA/cm2 under an applied field of 9 V/µm. The ZnO nanowire pad arrays were integrated into coplanar-gate FEAs and enhanced gate-controlled device characteristics were obtained. The gate-controlled capability was studied via microscopic in-situ measurements of the field emission from the ZnO nanowires in the coplanar-gate FEAs. Based on the results of both simulations and experiments, we attributed the enhanced gate-controlled device capabilities to more efficient emission of electrons from the ZnO nanowires as a result of the increase edge area by designing ring-shaped ZnO nanowire pad. The results are important to the realization of large-area gate-controlled FEAs based on nanowire emitters for use in vacuum electronic devices.