An analytical model for discretized doped InAlAs/InGaAs heterojunction HEMT for higher cut-off frequency and reliability

In the proposed work the model has been formulated for discretized doped HEMT, where the conventional uniformly doped, pulsed doped and delta doped structure are the special cases. An expression for sheet carrier density has been formulated considering the effect of doping-thickness product and has been extended to calculate drain current, transconductance, capacitance and cut-off frequency of the device. The model also takes into account the non-linear relationship between sheet carrier density and quasi Fermi energy level to validate it from subthreshold region to high conduction region. The results so obtained have been compared with pulsed doped structure to validate the model. The analysis concentrates on the distance of doping from the heterojunction and gate electrode. Different design criteria have been given to dope the carriers (amount and distance) in different regions to optimize the performance for higher sheet carrier density/parallel conduction voltage/effective parallel conduction voltage (V_c−V_off) to increase the transconductance, cut-off frequency and reliability of the device.     

Microwave Dielectric Properties of Hexagonal 12R-Ba3LaNb3O12 Ceramics

The dielectric properties of dense ceramics of the n =0 member of a newly identified homologous series Ba_{3+ n} LaNb₃Ti _n O_{12+3 n} , where n =0, 1, and 2, are reported. Single-phase powders can be obtained from the mixed-oxide route at 1350°C and dense ceramics (>97% of the theoretical X-ray density) with uniform microstructures (3–5 μm) can be obtained by sintering in air at 1500°C. The ceramics are excellent dc insulators with a band gap >2.6 eV that resonate at microwave frequencies with a relative permittivity, ɛ_r∼44, a quality factor, Q × f _r, of ∼9000 at f _r∼5.5 GHz and a temperature coefficient of resonant frequency, TC_f,∼−100 ppm/K.     

测量并抑制存储器件中的软误差

软误差是半导体器件中无法有意再生的“干扰”(即数据丢失)。它是由那些不受设计师控制的外部因素所引起的，包括α粒子、宇宙射线和热中子。许多系统能够容忍一定程度的软误差。例如，如果为音频、视频或静止成像系统设计一个预压缩捕获缓冲器或后置解压缩重放缓冲器，则一个偶然出现的缺陷     

Nanoscale avalanche photodiodes for highly sensitive and spatially resolved photon detection

Integrating nanophotonics with electronics could enhance and/or enable opportunities in areas ranging from communications and computing to novel diagnostics. Light sources and detectors are important elements for integration, and key progress has been made using semiconducting nanowires and carbon nanotubes to yield electrically driven sources and photoconductor detectors. Detection with photoconductors has relatively poor sensitivity at the nanometre scale, and thus large amplification is required to detect low light levels and ultimately single photons with reasonable response time. Here, we report avalanche multiplication of the photocurrent in nanoscale p-n diodes consisting of crossed silicon-cadmium sulphide nanowires. Electrical transport and optical measurements demonstrate that the nanowire avalanche photodiodes (nanoAPDs) have ultrahigh sensitivity with detection limits of less than 100 photons, and subwavelength spatial resolution of at least 250 nm. Crossed nanowire arrays also show that nanoAPDs are reproducible and can be addressed independently without cross-talk. NanoAPDs and arrays could open new opportunities for ultradense integrated systems, sensing and imaging applications.     

Dispersion Modeling of Leachates from Thermal Power Plants

Ground and surface water contamination due to leaching of trace elements from ash ponds is a major environmental challenge for thermal power plants. Leaching of trace elements from the ash ponds indicated significant concentration of nine trace elements (Na, K, Mg, Ca, Fe, Pb, Mn, Cu, and Zn) in the leachates of various thermal power plants. The empirical models developed for the prediction of various trace elements i.e., Mn, Cu, Fe, Zn, and Pb, followed first-order reaction rate kinetics. The empirical models derived from the laboratory scale models were subsequently modified to account for the changes in the chemistry, mineralogy, and morphology of fly ash with respect to time which correlated well with the real field data with regression coefficients varying from 0.93 to 0.98. The modified empirical models predicted concentrations of the trace elements within ±3% of the observed values for four thermal power plants with standard deviation varying from 0.001 to 0.032.     

Lasing in single cadmium sulfide nanowire optical cavities

The mechanism of lasing in single cadmium sulfide (CdS) nanowire cavities was elucidated by temperature-dependent and time-resolved photoluminescence (PL) measurements. Temperature-dependent PL studies reveal rich spectral features and show that an exciton-exciton interaction is critical to lasing up to 75 K, while an exciton-phonon process dominates at higher temperatures. These measurements together with temperature and intensity dependent lifetime and threshold studies show that lasing is due to formation of excitons and, moreover, have implications for the design of efficient, low threshold nanowire lasers.     

Phonon‐Assisted Electro‐Optical Switches and Logic Gates Based on Semiconductor Nanostructures

High‐performance nanostructured electro‐optical switches and logic gates are highly desirable as essential building blocks in integrated photonics. In contrast to silicon‐based optoelectronic devices, with their inherent indirect optical bandgap, weak light‐modulation mechanism, and sophisticated device configuration, direct‐bandgap‐semiconductor nanostructures with attractive electro‐optical properties are promising candidates for the construction of nanoscale optical switches for on‐chip photonic integrations. However, previously reported semiconductor‐nanostructure optical switches suffer from serious drawbacks such as high drive voltage, limited operation spectral range, and low modulation depth. High‐efficiency electro‐optical switches based on single CdS nanobelts with low drive voltage, ultra‐high on/off ratio, and broad operation wavelength range, properties resulting from unique electric‐field‐dependent phonon‐assisted optical transitions, are demonstrated. Furthermore, functional NOT, NOR, and NAND optical logic gates are demonstrated based on these switches. These switches and optical logic gates represent an important step toward integrated photonic circuits.     

Electroplated nickel based micro-machined disk resonators for high frequency applications

Microelectromechanical system (MEMS) based resonators can be used for filtering and frequency synthesis applications in many subcomponents of radio frequency wireless integrated circuits due to their small size, high level of frequency selectivity, low cost batch fabrication, ease of integration with CMOS circuits. Electroplated nickel is an attractive low cost material for CMOS compatible MEMS due to their low deposition temperatures. Among the different modes of vibration, radial-contour mode resonators are preferred for high frequency applications because they offer higher effective stiffness. Two different types of electroplated nickel based radial-contour bulk-mode circular disk resonator geometries which depend on capacitive actuation and readout technique is presented in this work. Material, mechanical and electrical characterizations were performed on these structures to show their functionality.     

Computer-aided diagnosis of auto-immune disease using capsule neural network

Manual analysis of the indirect-immunofluorescence (IIF) human epithelial cell Type-2 (HEp-2) cell image for the diagnosis of an auto-immune disease is a subjective and time-consuming process, and it is also prone to human-errors. The present work proposes an automatic capsule neural network (CapsNet) based framework for HEp-2 cell image classification to compensate for the deficiencies present in the prominent convolution neural network (CNN) based frameworks. In CNNs, the spatial relationship between the features present in the anti-nuclear antibodies (ANA) patterns, found in the IIF HEp-2 cell image (ANA-IIF image) is lost which increases the chance of detection of false-positives. In the proposed CapsNet based model, the max-pooling layer has been replaced with advanced dynamic routing algorithm and scalar outputs are replaced with the vector output, thus the richer representation of the same feature without the loss of spatial relationship with respect to the other features are made possible. The proposed framework recognizes ANA-IIF images with an average accuracy of 95.00% for 10-fold cross-validations. The experimental result also shows that the proposed model performs better than the other CNN based classification models for human epithelial cell image classification task.