Compact analytical model for single gate AlInSb/InSb high electron mobility transistors

We have developed a 2D analytical model for the single gate Al In Sb/In Sb HEMT device by solving the Poisson equation using the parabolic approximation method.The developed model analyses the device performance by calculating the parameters such as surface potential,electric field distribution and drain current.The high mobility of the Al In Sb/In Sb quantum makes this HEMT ideal for high frequency,high power applications.The working of the single gate Al In Sb/In Sb HEMT device is studied by considering the variation of gate source voltage,drain source voltage,and channel length under the gate region and temperature.The carrier transport efficiency is improved by uniform electric field along the channel and the peak values near the source and drain regions.The results from the analytical model are compared with that of numerical simulations(TCAD) and a good agreement between them is achieved.     

Syntheses and Magnetic-Properties of Zn-Diluted Sr-Based Perovskite Cobalt Oxides, Sr1?x Zn x CoO3; 0.05≤x≤0.3

In order to check the solubility of Zn in the (Sr_1?x Zn _x )CoO₃ perovskite structure and their research findings, several polycrystalline samples have been prepared under wide extreme synthesis conditions at 6?GPa/1300?C1650?°C. While 0.05??x??0.3 compositions revealed single phased cubic structure materials, x>0.3 showed multi-phased materials for (Sr_1?x Zn _x )CoO₃ system. Like other substituted perovskite cobalt oxide systems (Ca, Y, Ho and Ce), the transport properties of the present materials show rather sizable changes with respect to ??x??, although there are insignificant variations in lattice parameter and in Curie temperature, T _c . All the present samples show soft ferromagnetism with T _c in the range of 272?C285?K for 0.05??x??0.3. The effective paramagnetic moment, P _eff determined from the paramagnetic region decreases upon the substitution of Zn for Sr-site. These P _eff (3.3?C2.8???_B/Co) values for 0.05??x??0.3 compositions seem to suggest that the Co⁴⁺ lie in intermediate spin (IS) state for the present (Sr_1?x Zn _x )CoO₃ series, although they are slightly smaller than those expected for IS-Co⁴⁺; P _eff=3.87???_B/Co. The electrical resistivity is found to increase with increase of ??x?? for the investigated samples. The temperature and field dependence of both positive and negative magnetoresistance (MR) are noted for the Zn substituted samples. About 5% of ?CMR is observed for x=0.05 sample around the transition temperature (280?K) under the field strength difference, ??H=90?kOe. The present research findings are compared with our previous results on different perovskite cobalt oxides.     

Operation method study based on the energy balance of an independent microgrid using solar-powered water electrolyzer and an electric heat pump

A completely energy-independent microgrid (green microgrid) was examined in this work with the aims of abating greenhouse gas emissions by spreading the use of green energy, providing energy backup systems for disaster, and increasing the energy utilization efficiency with the use of exhaust heat. This paper analyzed the energy supply to six houses in a cold region. The green microgrid consisted of photovoltaics, water electrolyzers, proton-exchange membrane fuel cells (PEFCs), and heat pumps. To investigate the operation method and the capacity of each piece of equipment in the arrangement, a distributed system with two or more sets of equipment and a central system with one set of equipment were analyzed by a genetic algorithm. By introducing the prior energy need pattern of a cold region into the proposed system, the operation method and equipment capacity based on the power and heat balance were clarified. By introducing the partial load performance of a water electrolyzer and a PEFC into the analysis program, the operation method of each system was investigated. It was found that the area of a solar cell of a distributed system could be reduced by 12% as compared to a central system.     

Cluster synthesis and direct ordering of rare-earth transition-metal nanomagnets

Rare-earth transition-metal (R-TM) alloys show superior permanent magnetic properties in the bulk, but the synthesis and application of R-TM nanoparticles remains a challenge due to the requirement of high-temperature annealing above about 800 °C for alloy formation and subsequent crystalline ordering. Here we report a single-step method to produce highly ordered R-TM nanoparticles such as YCo(5) and Y(2)Co(17), without high-temperature thermal annealing by employing a cluster-deposition system and investigate their structural and magnetic properties. The direct ordering is highly desirable to create and assemble R-TM nanoparticle building blocks for future permanent-magnet and other significant applications.     

Effect of KCl on the bulk growth KDP crystals by Sankaranarayanan-Ramasamy method

The effect of the addition of potassium chloride (KCl) in bulk growth unidirectional 〈0 0 1〉 potassium dihydrogen phosphate (KDP) grown from aqueous solution by Sankaranarayanan-Ramasamy (SR) method has been studied. The crystal of 15 mm diameter, 95 mm height was grown by SR method. Addition of 5 M% KCl in the bulk growth medium increases the quality as well as the growth rate. The grown crystals were characterized by UV–Vis spectroscopy, microhardness and dielectric studies. It reveals that the SR method grown crystalline quality and perfection is better than the conventional method grown crystal.     

The twin-transistor noise-tolerant dynamic circuit technique

This paper describes a new circuit technique for designing noise-tolerant dynamic logic. It is shown that voltage scaling aggravates the crosstalk noise problem and reduces circuit noise immunity, motivating the need for noise-tolerant circuit design. In a 0.35-μm CMOS technology and at a given supply voltage, the proposed technique provides an improvement in noise immunity of 1.8×(for an AND gate) and 2.5×(for an adder carry chain) over domino at the same speed. A multiply-accumulate circuit has been designed and fabricated using a 0.35-μm process to verify this technique. Experimental results indicate that the proposed technique provides a significant improvement in the noise immunity of dynamic circuits (>2.4x) with only a modest increase in power dissipation (15%) and no loss in throughput     

A 2D Transconductance and Sub-threshold behavior model for triple material surrounding gate (TMSG) MOSFETs

A 2D analytical model for transconductance, Sub-threshold current and Sub-threshold swing for Triple Material Surrounding Gate MOSFET (TMSG) is presented in this paper. Based on the solution of two dimensional Poisson equation, the physics based model of sub-threshold current of the device is derived. The model also includes the effect of gate oxide thickness and silicon thickness on the sub-threshold swing characteristics. Transconductance to drain current ratio of the triple material surrounding gate is calculated since it is a better criterion to access the performance of the device. The effectiveness of TMSG design was scrutinized by comparing with other triple material and dual material gate structures. Moreover the effect of technology parameter variations is also studied and proposed. This proposed model offers basic guidance for design of TMSG MOSFETs. The results of the analytical model are compared with the MEDICI simulation results thus providing validity of the proposed model.     

Photophysical and photochemical investigations on triazole ring linked chalcone containing polymethacrylates

A series of polymethacrylates containing triazole ring linked chalcone were designed and synthesized. These conjugated chalcone polymers are modulate under the light depending on the pendant substituents (–N(CH₃)₂, CH₃, OCH₃, Br, H & NO₂). The steady-state absorption and emission spectroscopic techniques have been used to investigate intramolecular charge transfer (ICT) behaviour of the polymers. Absorption spectra in different organic solvents demonstrate the presence of ICT in polymer 5a. On the other hand, its excited singlet state exhibits high ICT characters as manifested by polarity of solvents. Interestingly, ICT emission maximum is strongly red shifted (53 nm). The emission intensities of fluorophore are compared with those measured after crosslinking, suggesting that the statically quenched fluorophores are entirely non-emissive. The emission decay of polymer 5a displays bi-exponentially with life time of 0.52 and 1.62 ns ascribed to presence of locally excited ICT state. Cyclic voltammogram demonstrates irreversible oxidation potential at 0.9 V indicates formation mono-radical cation.     

Comments on “Analysis of wide inclined slot coupled narrowwall coupler between dissimilar rectangular waveguides”[and reply]

Comments by D. Satyanarayana and Ajay Chakrabarty claim that the original paper [see IEEE Trans. Antennas Propagat., vol. AP-37, no. 9, p. 1116-23, 1989] has not considered the contribution of TE_no mode in the scattered fields in the waveguide region and imply that the Green's function employed is incomplete. However there is a discussion on the singular contribution with a mathematical expression containing the appropriate Dirac delta function. It is also obvious that the specific terms of the cavity Green' s functions that treat the waveguide wall thickness do not have such a singular contribution present. Therefore, Green's functions employed in the paper are complete and rigorous. D. Satyanarayana and Ajay Chakrabarty reply to these further comments by the original author     

Efficient and accurate evaluation of external mutual couplingbetween compound broad wall slots

The efficient and accurate evaluation of external mutual coupling between compound broad-wall slots cut in rectangular waveguides is addressed. The special case of longitudinal slots is also considered. Errors introduced by approximations used in some mutual coupling expressions are investigated and numerical results are presented for a range of waveguide and slot parameters. It is shown that for most applications, mutual coupling expressions can be determined in terms of single numerical integrals