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In this work pure and transition elements (Ni and Cu) doped Zinc Oxide is prepared. All the samples were prepared through chemical co-precipitation method, by using sulfates of metallic precursors. We have doped pure ZnO with Ni and Cu by 3% by weight concentration. Further the structural, Crystallite size and band gap approximation studies were performed by utilizing X-ray diffraction and spectroscopic techniques respectively. X-ray diffraction (XRD) result indicates that the sample possess a crystalline Wurtzite single phase. Crystallite size is in 19-30 nm range. PL characterization gives optical band gap that is 2.65-3.0 2 eV. FTIR gives the molecular band present in the samples. UV-Vis shows red shift in peak wavelength.

Inelastic phonon scattering in graphene field-effect transistors (FETs) is studied by numerically solving the Boltzmann transport equation in three dimensional real and phase spaces (x, kx, ky). A kink behavior due to ambipolar transport agreeing with experiments is observed. While low field behavior has previously been mostly attributed to elastic impurity scattering in earlier studies, it is found in the study that even low field mobility is affected by inelastic phonon scattering in recent graphene FET experiments reporting high mobilities . As the FET is biased in the saturation regime, the average carrier injection velocity at the source end of the device is found to remain almost constant with regard to the applied gate voltage over a wide voltage range, which results in significantly improved transistor linearity compared to what a simpler model would predict. Physical mechanisms for good linearity are explained, showing the potential of graphene FETs for analogue electronics applications.

High frequency performance limits of graphene field-effect transistors (FETs) down to a channel length of 20nm are examined by using self-consistent quantum simulations. The results indicate that although Klein band-to-band tunneling is significant for sub-100nm graphene FET, it is possible to achieve a good transconductance and ballistic on-off ratio larger than 3 even at a channel length of 20nm. At a channel length of 20nm, the intrinsic cut-off frequency remains at a couple of THz for various gate insulator thickness values, but a thin gate insulator is necessary for a good transconductance and smaller degradation of cut-off frequency in the presence of parasitic capacitance. The intrinsic cut-off frequency is close to the LC characteristic frequency set by graphene kinetic inductance and quantum capacitance, which is about 100GHz \cdot {\mu}m divided by the gate length., Comment: 24 pages, 7 figures

Graphene nanoribbon tunneling FETs (GNR TFETs) are promising devices for post-CMOS low-power applications because of the low subthreshold swing, high I_on/I_off, and potential for large scale processing and fabrication.This paper combines atomistic quantum transport modeling with circuitsimulation to explore GNR TFET circuits for low-power applications.A quantitative study of the effects of variations on the performance and reliabilityof GNR TFET circuits is also presented. Simulation results indicate that GNR TFET circuits are extremely competitive in performance in comparison to conventional CMOS circuits at comparable operating points, with static power consumption that is lower by 8-9 orders of magnitude. It is also observed that GNR TFET circuits are susceptible to parameter variations, motivating engineering and design challenges to be addressed by the device and CAD communities.

The recently discovered graphene nanoribbon (GNR) is ideal for tunneling FETs due to its symmetric bandstructure, light effective mass, and monolayer-thin body. In this work, we examine the device physics of p-i-n GNR tunneling FETs using atomistic quantum transport simulations. The important role of the edge bond relaxation in the device characteristics is identified. The device, however, has ambipolar I-V characteristics, which are not preferred for digital electronics applications. A properly designed gate underlap can effectively suppress the ambipolar I-V. A subthreshold slope of 14mV/dec and a significantly improved on-off ratio can be obtained by the p-i-n GNR tunneling FETs. The on-current, which is low due to the tunneling barrier, can be improved by a lattice vacancy in the tunneling junction region due to the induced middle bandgap state.

In nanoscale silicon CMOS, the contact resistance could considerable lower the on-current and significantly increase the delay. Most models of metal-semiconductor and silicide-silicon contacts remain over-simplified and phenomenological. In this study, ab initio simulations based on the density-functional theory (DFT) and quantum transport simulations based on the non-equilibrium Green's function (NEGF) formalism have been developed to model and investigate the technologically important silicide-silicon contacts. The results indicate that in spite of the existence of a considerable metal-induced bandgap states, a carefully designed interfacial doping scheme can effectively modulate the Schottky barrier height (SBH). The modulation of the SBH can transform a rectifying I-V characteristic of a Schottky diode to a nearly linear I-V characteristic of an Ohmic contact even without changing the bulk semiconductor doping density.

As silicon CMOS scales to the nanoscale regime, the contact resistance is becoming comparable to the channel resistance at on-state, which could considerably lower the on-current and significantly increase the delay. This trend is expected to exacerbate as scaling continues. Low-resistance silicides, such as CoSi 2 and NiSi 2 , are widely used in high performance transistors to enhance the performance. Modeling and understanding silicide contacts are challenged by the importance of interface states, quantum effects, dopants, defects, and even atomistic scale features of the interface, and the ab initio simulation is appropriate for addressing these challenges from first principles. A previous first-principal simulation study has been focusing on monosilicide for a specific crystal orientation [1]. In this study, by using the ab initio density-functional theory (DFT), we systematically examine the properties of metal-induced gap states (MIGS), effects of different interface dopants, and the contact barrier properties for NiSi 2 /Si and CoSi 2 /Si contacts with different silicon crystal orientations. The study provides atomistic scale insights into the contact properties for technologically important disilicide-silicon contacts.

Tunneling field-effect transistors (FETs) have been intensely explored recently due to its potential to address power concerns in nanoelectronics. The recently discovered graphene nanoribbon (GNR) is ideal for tunneling FETs due to its symmetric bandstructure, light effective mass, and monolayer-thin body. In this work, we examine the device physics of p-i-n GNR tunneling FETs using atomistic quantum transport simulations. The important role of the edge bond relaxation in the device characteristics is identified. The device, however, has ambipolar I-V characteristics, which are not preferred for digital electronics applications. We suggest that using either an asymmetric source-drain doping or a properly designed gate underlap can effectively suppress the ambipolar I-V. A subthreshold slope of 14mV/dec and a significantly improved on-off ratio can be obtained by the p-i-n GNR tunneling FETs.

Graphene, which is mechanically flexible, electrically conductively, and optically nearly transparent, is a promising contact material in semiconductor devices such as solar cells and touch screen sensors. We present a method of obtaining the barrier height and transport properties of graphene-silicon contacts by self-consistently solving the Poisson equation and carrier transport equation. It is found that the contact barrier height is sensitive to the doping density of silicon and can be modulated by gating, in contrast to conventional metal-semiconductor contacts. Despite of being a continuous film, the contact resistance of a monolayer graphene to silicon can be modulated by orders of magnitude by using a bottom gate. The modulation of the contact resistance decreases significantly as the number of graphene layers increases and becomes negligible when the number of the graphene layers is larger than about 6. The results indicate the unique properties of graphene-semiconductor contacts.

Chemical structure of a chemical is useful for the synthesis of new compounds with more specific actions and fewer adverse reactions, to increase/decrease the duration of action of the original drug or to get a more potent compound, to restrict the action to a specific system of the body and to reduce the adverse reactions, toxicity and other disadvantages associated. Recently it has been observed that some of the fungicides are loosing their effects. So analogous compounds can be designed as substitute, if their structures are known. A rational approach to test these fungicides is to know the three dimensional structure of these compounds and macromolecular receptor sites as well as their molecular complex. The structures of these compounds can be obtained by X-ray diffraction method in crystalline form and they will invariably be similar to their structure in solutions. The composition of crystal (RS)-2-(2,4-dichlorophenyl)-1-(1H-1, 2,4-trizole-1-y1) hexane-2-ol or hexaconazole and Tricyclazole are confirmed by comparing the infra-red spectra of two components. The unit cell parameters of Hexaconozole are a=10. 9068(7) A, b=10.9895(7) A c=13.6124(8) A, α=90o, β=106.554(2)o, γ=90.000(5)o. The Crystal system is Monoclinic, and space group P21/c . The unit cell parameters of Tricyclazole are a=14.896(5) A, b=7.410(5)A, c=7.556(5) A, α=90(5)o, β=90.000(5)o, γ=90.000(5)o.The Crystal system is Orthorhombic and space group is Pca21.

High Frequency potential of graphene field-effect transistors (FETs) is explored by quasi-static self-consistent ballistic and dissipative quantum transport simulations. The unity power gain frequency fMAX and the cut-off frequency fT are modeled at the ballistic limit and in the presence of inelastic phonon scattering for a gate length down to 5 nm. Our major results are (1) with a thin high-κ gate insulator, the intrinsic ballistic fT is above 5 THz at a gate length of 10 nm. (2) Inelastic phonon scattering in graphene FETs lowers both fT and fMAX, mostly due to decrease of the transconductance. (3) fMAX and fT are severely degraded in presence of source and drain contact resistance. (4) To achieve optimum extrinsic fMAX performance, careful choice of DC bias point and gate width is needed.

High-field transport in graphene is studied by the Monte Carlo simulation. The results indicate velocity and current saturation in agreement with a recent experiment [I. Meric, M. Y. Han, A. F. Young, B. Oezyilmaz, P. Kim, and K. Shepard, Nat. Nanotechnol. 3, 654 (2008)]. The saturation current scales as the square root of the charge density, or equivalently, the square root of the gate overdrive voltage, which is qualitatively different from silicon field-effect transistors. By analytical fitting to the numerical simulation results, a simple expression of the field-dependent mobility is obtained at different strengths of charged impurity scattering.