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91.
The activation energy of the drain current in polysilicon thin-film transistors (TFTs) and the effects of hydrogenation on this energy are discussed. The activation energy data are fitted using different models of the density of states in the material. It is shown that a model which assumes a distribution of brand tail states and localized deep states can account for the activation energy data of unhydrogenated polysilicon TFTs. However, the activation energy data on hydrogenated TFTs cannot be explained with the band tail model. Instead, a simple model of deep states localized at the grain boundary can fit this data quite accurately. Also, it is shown that there is a characteristic kink in the activation energy data of the hydrogenated TFTs which is a signature of the location of the deep states relative to the valence band edge. Analysis indicates that these deep states are located approximately 0.36 eV from the valence band edge. This value is consistent with that obtained from absorption measurements using photothermal deflection spectroscopy 相似文献
92.
Sardar Muhammad Bilal Atta ur Rehman Khan Samee Ullah Khan Sajjad A. Madani Babar Nazir Mazliza Othman 《Wireless Personal Communications》2014,77(4):2497-2515
Over the last few years, vehicular ad hoc networks (VANETs) have gained popularity for their interesting applications. To make efficient routing decisions, VANET routing protocols require road traffic density information for which they use density estimation schemes. This paper presents a distributed mechanism for road vehicular density estimation that considers multiple road factors, such as road length and junctions. Extensive simulations are carried out to analyze the effectiveness of the proposed technique. Simulation results suggested that, the proposed technique is more accurate compared to the existing technique. Moreover, it facilitate VANET routing protocols to increase packet delivery ratio and reduce end-to-end delay. 相似文献
93.
Recapillarity: Electrochemically Controlled Capillary Withdrawal of a Liquid Metal Alloy from Microchannels 下载免费PDF全文
This paper describes the mechanistic details of an electrochemical method to control the withdrawal of a liquid metal alloy, eutectic gallium indium (EGaIn), from microfluidic channels. EGaIn is one of several alloys of gallium that are liquid at room temperature and form a thin (nm scale) surface oxide that stabilizes the shape of the metal in microchannels. Applying a reductive potential to the metal removes the oxide in the presence of electrolyte and induces capillary behavior; we call this behavior “recapillarity” because of the importance of electrochemical reduction to the process. Recapillarity can repeatably toggle on and off capillary behavior by applying voltage, which is useful for controlling the withdrawal of metal from microchannels. This paper explores the mechanism of withdrawal and identifies the applied current as the key factor dictating the withdrawal velocity. Experimental observations suggest that this current may be necessary to reduce the oxide on the leading interface of the metal as well as the oxide sandwiched between the wall of the microchannel and the bulk liquid metal. The ability to control the shape and position of a metal using an applied voltage may prove useful for shape reconfigurable electronics, optics, transient circuits, and microfluidic components. 相似文献
94.
95.
Single-phase ceramics in the SrLa4?x Pr x La4Ti5O17 (0 ≤ x ≤ 4) series were processed via a solid-state sintering route. X-ray diffraction analysis revealed single-phase ceramics for all the compositions. The molar volume (V m) decreased while the theoretical density (ρ th) increased with increase in the Pr content. Substitution of Pr3+ decreased the relative permittivity (ε r) and temperature coefficient of resonant frequency (τ f) due to its smaller ionic polarizability (α d) and ionic radius than La3+. In the present study, ε r ≈ 54.2, Q u f 0 ≈ 7935 GHz, and τ f ≈ ?20.3 ppm/°C were achieved for the composition with x = 2 (i.e., SrLa2Pr2Ti5O17). 相似文献
96.
S. Krishnankutty R. M. Kolbas M. A. Khan J. N. Kuznia J. M. Van Hove D. T. Olson 《Journal of Electronic Materials》1992,21(6):609-612
The low temperature (77 K) photoluminescence characteristics of Al
x
Ga1-x
N-GaN strained layer quantum wells with differentx values grown by metalorganic chemical vapor deposition (MOCVD) were investigated. The photoluminescence spectra were useful
in analyzing both quantum confinement effects and strain induced energy shifts. The strain induced shifts were found to be
a strong function of aluminum compositionx. A model was developed to calculate the strain induced bandgap shifts atk = 0. The values predicted by this model which took into account the wurtzite crystal structure of the material system, were
in good agreement with (i.e. within 2 meV of) the experimentally measured shifts. 相似文献
97.
The classical central difference approximations of the derivative of a function based on Taylor series are the same as type III maximally linear digital differentiators for low frequencies. A new finite difference formula is derived which can be implemented as a full band type IV maximally linear differentiator. The differentiator is compared with type III maximally linear and type IV equiripple minimax differentiators. A modification is proposed in the design to minimise the region of inaccuracy near the Nyquist frequency edge 相似文献
98.
Sangmoo Choi Canek Fuentes-HernandezMinseong Yun Amir DindarTalha M. Khan Cheng-Yin WangBernard Kippelen 《Organic Electronics》2014,15(12):3780-3786
We report on a reverse stamping method to produce via-holes in circuits comprising acene-based top-gate organic field-effect transistors (OFETs) having a CYTOP/Al2O3 (by atomic layer deposition) bilayer gate dielectric. This method relies on the weak adhesive force that exists between a small molecule acene film and a polymer to enable easy delamination of the bilayer gate dielectric by using a PDMS stamp. We demonstrate the effectiveness of this method by fabricating simple circuits using top-gate triisopropylsilylethynyl pentacene (TIPS-pentacene)/poly (triarylamine) (PTAA) OFETs. 相似文献
99.
Z. -Q. Fang D. C. Look A. Krtschil A. Krost F. A. Khan I. Adesida 《Journal of Electronic Materials》2006,35(4):613-617
Extended defects on the top surface of a 250-μm-thick free-standing GaN sample, grown by hydride vapor phase epitaxy (HVPE),
were studied by deep level transient spectroscopy (DLTS) and scanning surface potential microscopy (SSPM). For comparison,
similar studies were carried out on as-grown HVPE-GaN samples. In addition to the commonly observed traps in as-grown HVPE-GaN,
the DLTS measurements on free-standing GaN reveal a very high concentration of deep traps (∼1.0 eV) within about 300 nm of
the surface. These traps show nonexponential capture kinetics, reminiscent of those associated with large defects, that can
accumulate multiple charges. The SSPM measurements clearly reveal the presence of charged microcracks on the top surface of
the sample. It appears that the “giant traps” may be associated with these microcracks, but we cannot rule out the involvement
of other extended defects associated with the near-surface damage caused by the polishing/etching procedure. 相似文献
100.
Cuiping Zhang Jingxuan Cai Chuwei Liang Arshad Khan Wen‐Di Li 《Advanced functional materials》2019,29(35)
Metallic nanofiber networks (MNFNs) are very promising for next‐generation flexible transparent electrodes (TEs) since they can retain outstanding optical and electrical properties during bending due to their ultralong and submicron profile. However, it is still challenging to achieve cost‐effective and high‐throughput fabrication of MNFNs with reliable and consistent performance. Here, a cost‐effective method is reported to fabricate high‐performance MNFN‐TEs via templated electrodeposition and imprint transfer. The fabricated electrodeposition template has a trilayer structure of glass/indium tin oxide/SiO2 with nanotrenches in the insulating SiO2 that can be utilized for repeated electrodeposition of the MNFNs, which are then transferred to flexible substrates. The fabricated TEs exhibit excellent optical transmittance (>84%) and electrical conductivity (<0.9 Ω sq?1) and show desirable mechanical flexibility with a sheet resistance <2 Ω sq?1 under a bending radius of 3 mm. Meanwhile, the MNFN‐TEs reproduced from the reusable template show consistent and reliable performance. Additionally, this template‐based method can realize the direct patterning of MNFN‐TEs with arbitrary conductive patterns by selective masking of the template. As a demonstration, a flexible dynamic electroluminescent display is fabricated using TEs made by this method, and the light‐emitting pattern is observable from both sides. 相似文献