Possible acception criteria for structure functions

This paper deals with the verification of thermal transient evaluation implementations. This subject is relevant because e.g. the upcoming standard will describe the thermal transient measurement as a standard method to estimate the junction-to-case thermal resistance [1], [2], thus anybody can create their own implementation of the evaluation method. We have to have a method to verify these implementations. For this reason we examined the result of the NID (Network Identification by Deconvolution) method from different aspects. For these examinations we defined a multilayer structure as a reference structure and we analytically expressed the unit-step response and the cumulative structure function of this structure. Using the unit-step response as an input data set for the implementation in question we got an approximation of the structure function. Analysing this and the reference RC network we could define a practical maximum tolerance for the deviation between the analytical and the calculated functions.     

Simulation of vertical merged MOS elements with optical power supply

Functional optoelectronic vertical merged MOS (OVMMOS) elements with optical power supply increasing the packaging density for advanced high-speed low-voltage low-power deep-submicron ULSI are considered. Two types of new OVVMOS logical elements are proposed, analyzed and simulated. The simple reduced but adequate numerical electrical-optical model for the OVMMOS is formulated. Low-voltage low-power OVMMOS with combined channels for electrons and holes to increase integration level are simulated using two-dimensional (2D)-numerical device simulators. The problems of low light power operations and optimizations of OVMMOS elements are investigated using 2D simulators.     

Structural Evolution Following Spinodal Decomposition of the Pseudoternary Compound (Pb0.3Sn0.1Ge0.6)Te

Pseudoternary (Ge,Sn,Pb)Te compounds display favorable thermoelectric properties. Spinodal decomposition in the quasiternary (Ge,Sn,Pb)Te system is at the origin of a wide solubility gap at low Sn concentrations. The structural evolution of the spinodal decomposition was investigated as a function of aging time at 500°C, using x-ray diffraction, electron microscopy, and scanning electron microscopy. The evolution of the structure at 500°C consists initially of a short diffusion-controlled demixing stage into Pb- and Ge-rich coherent areas, with compositions corresponding to the inflection points of the free-energy curve. The Pb-rich areas adopt configurations associated with the directions of the soft elastic moduli of the cubic compound. Both the Pb- and Ge-rich areas are supersaturated and undergo in a second stage a nucleation and growth process and give rise to a biphased structure with equilibrium compositions corresponding to the boundaries of the miscibility gap. The resulting Pb-rich areas display a relatively stable microstructure suggesting the presence of long-range interactions between the Pb-rich precipitates in the Ge-rich matrix.     

Atomic layer deposition of aluminum oxide films for carbon nanotube network transistor passivation

Ultra-thin (2-5 nm thick) aluminum oxide layers were grown on non-functionalized individual single walled carbon nanotubes (SWCNT) and their bundles by atomic layer deposition (ALD) technique in order to investigate the mechanism of the coating process. Transmission electron microscopy (TEM) was used to examine the uniformity and conformality of the coatings grown at different temperatures (80 degrees C or 220 degrees C) and with different precursors for oxidation (water and ozone). We found that bundles of SWCNTs were coated continuously, but at the same time, bare individual nanotubes remained uncoated. The successful coating of bundles was explained by the formation of interstitial pores between the individual SWCNTs constituting the bundle, where the precursor molecules can adhere, initiating the layer growth. Thicker alumina layers (20-35 nm thick) were used for the coating of bottom-gated SWCNT-network based field effect transistors (FETs). ALD layers, grown at different conditions, were found to influence the performance of the SWCNT-network FETs: low temperature ALD layers caused the ambipolarity of the channel and pronounced n-type conduction, whereas high temperature ALD processes resulted in hysteresis suppression in the transfer characteristics of the SWCNT transistors and preserved p-type conduction. Fixed charges in the ALD layer have been considered as the main factor influencing the conduction change of the SWCNT network based transistors.     

High-performance and broadband photodetection of bicrystalline(GaN)1-x(ZnO)x solid solution nanowires via crystal defect engineering

Crystal defect engineering is widely used as an effective approach to regulate the optical and opto-electronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic perfor-mance.In this work,a high-performance photodetector based on(GaN)1-x(ZnO)x solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light.The highest responsivity of the photodetector is as high as 60,86 and 43 A/W under the irradiation of 365 nm,532 nm and 650 nm,respectively.The corresponding response time is as fast as 170,320 and 160 ms.Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire.Moreover,the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast trans-mission channels for photo-generated carriers,reducing the recombination of photo-generated carriers.Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.     

Multilayer PZT 95/5 Antiferroelectric Film Energy Storage Devices with Giant Power Density

A new type of energy storage devices utilizing multilayer Pb(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ films is studied experimentally and numerically. To release the stored energy, the multilayer ferroelectric structures are subjected to adiabatic compression perpendicular to the polarization direction. Obtained results indicate that electrical interference between layers (10–120 layers) during stress wave transit through the structures has an effect on the generated current waveforms, but no impact on the released electric charge. The multilayer films undergo a pressure‐induced phase transition to antiferroelectric phase at 1.7 GPa adiabatic compression and become completely depolarized, releasing surface screening charge with density equal to their remnant polarization. An energy density of 3 J cm^?3 is successfully achieved with giant power density on the order of 2 MW cm^?3, which is four orders of magnitude higher than that of any other type of energy storage device. The outputs of multilayer structures can be precisely controlled by the parameters of the ferroelectric layer and the number of layers. Multilayer film modules with a volume of 0.7 cm³ are capable of producing 2.4 kA current, not achievable in electrochemical capacitors or batteries, which will greatly enhance the miniaturization and integration requirements for emerging high‐power applications.     

Molecular dynamics simulation of the formation of bimetallic core-shell nanostructures with binary Ni–Al nanoparticle quenching

Journal of Materials Science - Employing isothermal molecular dynamics, we simulated the self-assembly of core-shell nanostructures in the course of quenching binary Ni–Al nanoparticles (NPs)...     

Solution‐Processed Ti3C2Tx MXene Antennas for Radio‐Frequency Communication

Highly integrated, flexible, and ultrathin wireless communication components are in significant demand due to the explosive growth of portable and wearable electronic devices in the fifth‐generation (5G) network era, but only conventional metals meet the requirements for emerging radio‐frequency (RF) devices so far. Here, it is reported on Ti₃C₂T_x MXene microstrip transmission lines with low‐energy attenuation and patch antennas with high‐power radiation at frequencies from 5.6 to 16.4 GHz. The radiation efficiency of a 5.5 µm thick MXene patch antenna manufactured by spray‐coating from aqueous solution reaches 99% at 16.4 GHz, which is about the same as that of a standard 35 µm thick copper patch antenna at about 15% of its thickness and 7% of the copper weight. MXene outperforms all other materials evaluated for patch antennas to date. Moreover, it is demonstrated that an MXene patch antenna array with integrated feeding circuits on a conformal surface has comparable performance with that of a copper antenna array at 28 GHz, which is a target frequency in practical 5G applications. The versatility of MXene antennas in wide frequency ranges coupled with the flexibility, scalability, and ease of solution processing makes MXene promising for integrated RF components in various flexible electronic devices.     

Preparation of immobilized Trametes pubescens laccase on a cryogel-type polymeric carrier and application of the biocatalyst to apple juice phenolic compounds oxidation

A new biocatalyst was prepared by the immobilization of a Trametes pubescens laccase, into a wide-pore poly(vinyl alcohol) cryogel. The known enzyme was produced and purified by the previously described procedure. The resulted laccase (yield 40%) has an activity of 46.4 U mg⁻¹ and 12.51 mg mL⁻¹ protein content. The enzyme was subsequently immobilized in a functionalized macroporous cryogel beads by a covalent immobilization technique. The time dependence of the immobilization process and the enzyme loading of the carrier material (5.2 mg g⁻¹ cryogel) were determined by measuring the decrease of protein amount in the enzyme solution. In conversion experiments, a higher stability of the immobilized biocatalyst compared to the free enzyme was evidenced. Steady-state kinetic characterization of four phenols (catechol, caffeic and chlorogenic acids, and catechin) has been performed with free and immobilized laccase, the catalytic parameters being determined and compared. The effect of both laccases (free and immobilized) on the phenol content of retailed apple juice samples, having the same initial composition, was also investigated by working in batch conversion. The variation in phenolic compound content has been compared with that of an untreated apple juice sample having initially the same content of phenolic compounds. A number of advantages resulted in using the immobilized laccase for the apple juice treatment (conservation to some extent of enzyme activity, higher content of phenols preserved, easy separation of the enzyme from the apple juice, therefore avoiding the possible unhealthy effects due to the remaining protein, etc.).