A Computational Study of Aspects of ZnO Nanorod Film Electro-Crystallisation

<p>A new generation of material technologies is being produced by tuning the properties of an existing material through control of the size and shape on the nanoscale. Zinc oxide is an excellent candidate for such an approach due to its possession of a plethora of useful properties, both mechanical and electronic, and a fantastically rich family of morphologies accessible on the nanoscale. A more detailed control over the nano-structure of these materials requires a more detailed understanding of the events that control the growth. We have undertaken computational studies of the electrodeposition of zinc oxide nano-rod films to open up and improve the understanding of the pathways, and events that facilitate the controlled selection of desired structures and therefore properties. We have applied methods that span vastly different scales to provide insight on the continuum and atomistic regimes. Specifically, we have developed a macroscopic transport model to track the evolution of crystallite shape, surrounding concentration distributions, and electric field variation. The macroscopic view is complemented with a classical description of crystal growth, in which we obtain the key parameters using quantum mechanical calculations.</p>

A Computational Study of Aspects of ZnO Nanorod Film Electro-Crystallisation

<p>A new generation of material technologies is being produced by tuning the properties of an existing material through control of the size and shape on the nanoscale. Zinc oxide is an excellent candidate for such an approach due to its possession of a plethora of useful properties, both mechanical and electronic, and a fantastically rich family of morphologies accessible on the nanoscale. A more detailed control over the nano-structure of these materials requires a more detailed understanding of the events that control the growth. We have undertaken computational studies of the electrodeposition of zinc oxide nano-rod films to open up and improve the understanding of the pathways, and events that facilitate the controlled selection of desired structures and therefore properties. We have applied methods that span vastly different scales to provide insight on the continuum and atomistic regimes. Specifically, we have developed a macroscopic transport model to track the evolution of crystallite shape, surrounding concentration distributions, and electric field variation. The macroscopic view is complemented with a classical description of crystal growth, in which we obtain the key parameters using quantum mechanical calculations.</p>

CHARACTERISTICS OF HYDROMETEOROLOGICAL HAZARDS IN NIZHNY NOVGOROD ACCORDING TO IN-SITU OBSERVATIONS OF ELECTRIC FIELD

The characteristics of hazardous meteorological phenomena in Nizhny Novgorod city based on the electric field observations are obtained in the present paper. As a result of the analysis of quasistationary electric field variation experimental data together with the meteorological data, statistics of thunderstorm events were obtained and their classification was carried out. The data of field observations are compared with the results of numerical calculations based on the WRF model.

Improved DC Performance Analysis of a Novel Asymmetric Extended Source Tunnel FET for Fast Switching Application

A two-dimensional analytical model for asymmetric extended source tunnel field effect transistor (AES-TFET) has been developed to obtain better device performance. The proposed device model has been analytically modelled and performed by solving 2-D Poisson’s equation. Surface potential distribution, electric field variation and band-to-band tunneling (BTBT) rate have been investigated by this numerical modelling. The source region of novel structure of TFET has been extended (varied 2 nm to 6 nm) to incorporate corner effect, which allows BTBT through a thin tunneling barrier, with controlled ambipolar conduction. This eventually produces better source-channel interface tunneling for a n-channel AES-TFET. 2-D numerical device simulator (SILVACO TCAD) has been used for simulation work. The simulated work has been finally validated by analytical modelling of AES-TFET. Better ION, IOFF and switching ratio has been obtained from this novel TFET structure.

Design and Investigation of F-Shaped Tunnel FET With Enhanced Analog/RF Parameters

In this manuscript, a novel physically doped single gate F-shaped tunnel FET is simulated and optimized. The designed configuration is well optimized and analyzed for different source thickness, source length, drain length with different lateral tunneling lengths between the source edge and gate dielectric. Also, we optimized some stand-points like threshold voltage, ION to IOFF current ratio, ambipolar conduction range, subthreshold swing and various capacitance to rectify the analog/RF performance of single gate F-shaped TFET. Regarding this, we concurrently optimize the lateral tunneling length between source and gate with optimization of source thickness. The variation in lateral tunneling length, the potential and strength of electric field at fixed Vgs voltage is varied which leads to effective change in the ON-current, average sub-threshold swing, and turn ON-voltage. Another side, as well as the source thickness vary, the electric field variation takes place near the edge of source, which leads to variation in the ON-current and ON-voltage. The performance parameters of single gate F-TFET is compared with single gate L-TFET, which is the incentive of this submitted work. The optimized single gate F-TFET have 0.30 V turn ON-voltage with 7.4 mV/decade average sub-threshold swing and high Ion/Ioff ratio approx 1013. Besides, a significant reduction in parasitic capacitance is beneficial to enhanced RF performance with better controllability on channel.

Physics Based Analytical Modeling of Asymmetric Elevated Source Tunnel FET (AES-TFET) for Better Tunnel Junction Device (TJD) Performance

In this paper, a two-dimensional analytical model for asymmetric elevated source tunnel field effect transistor (AES-TFET) has been developed to obtain better tunnel junction device performance. Device physics based analytical modelling is performed by solving 2-D Poisson’s equation. Surface potential distribution, electric field variation and band-to-band tunneling (B2B) rate have been investigated by this numerical modelling. In our proposed structure, the source has been elevated (varied 2 nm to 6 nm) to incorporate corner effect; which boosts the carrier transport via thin tunneling barrier, with controlled ambipolar conduction. This eventually produces better source-channel interface tunneling for a n-channel AES-TFET structure. 2-D numerical device simulator (SILVACO TCAD) has been used for simulation work. The simulated graphical representations have been finally validated by analytical modelling of AES-TFET.

Deep-Sea DC Resistivity and Self-Potential Monitoring System for Environmental Evaluation With Hydrothermal Deposit Mining

Environmental impact assessment has become an important issue for deep-sea resource mining. The International Seabed Authority has recently developed recommendations for guidelines on environmental assessment of resource mining effects. Several research and development groups have been organized to develop methods for environmental assessment of the seafloor and sub-seafloor under the “Zipangu in the Ocean program,” a part of the Cross-ministerial Strategic Innovation Promotion Program managed by the Cabinet Office of the Japanese government. One attempt planned for long-term environment and sub-seafloor structure monitoring uses a cabled observatory system. To support this observatory plan, we began development of a system to monitor the sub-seafloor resistivity and self-potential reflecting the physicochemical properties of ore deposits and the existence of hydrothermal fluid. The system, which mainly comprises an electro-magnetometer and an electrical transmitter, detects spatio-temporal changes in subseafloor resistivity and in self-potential. Because of the project’s policy changes, cabled observatory system development was canceled. Therefore, we tried to conduct an experimental observation using only a current transmitter and a voltmeter unit. Data obtained during three and a half months show only slight overall apparent resistivity variation: as small as 0.005 Ω-m peak-to-peak. The electrode pair closest to the hydrothermal mound shows exceptionally large electric field variation, with a semidiurnal period related to tidal variation. Results indicate difficulty of explaining electric field variation by seawater mass migration around the hydrothermal mound. One possibility is the streaming potential, i.e., fluid flow below the seafloor, in response to tides. However, we have not been able to perform rigorous quantitative analysis, and further investigation is required to examine whether this mechanism is effective. The system we have developed has proven to be capable of stable data acquisition, which will allow for long-term monitoring including industrial applications.