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The Preisach model of hysteresis admits simple device realizations. It is suggested in the paper that these realizations can be utilized as unique data storage devices as well as analog global optimizers.

A new hysteresis-based technique for random number generation is presented which can be efficiently implemented by using modern spintronics based nano-technology. Thermal fluctuation induced random switchings of rectangular hysteresis loops are utilized whose outputs result in the generation of random binary numbers. Mathematically, the random switching is treated as a repeated sequence of two exit problems for stationary stochastic processes, which are shown to be reduced to the solution of initial boundary value problems for the appropriate backward Kolmogorov equations. Analytical solution of these boundary value problems are carried out for the stationary Gaussian Markov Ornstein-Uhlenbeck process. An alternative approach to the analysis of the random switching based on stochastic processes on graphs is also discussed with special attention paid to the trade-offs between the strength of thermal noise and the widths of the hysteresis loops.

In this study, electronic properties of field-effect transistors (FETs) fabricated from exfoliated MoTe(2) single crystals are investigated as a function of channel thickness. The conductivity type in FETs gradually changes from n-type for thick MoTe(2) layers (above ≈ 65 nm) to ambipolar behavior for intermediate MoTe(2) thickness (between ≈ 60 and 15 nm) to p- type for thin layers (below ≈ 10 nm). The n-type behavior in quasi-bulk MoTe(2) is attributed to doping with chlorine atoms from the TeCl(4) transport agent used for the chemical vapor transport (CVT) growth of MoTe(2). The change in polarity sign with decreasing channel thickness may be associated with increasing role of surface states in ultra-thin layers, which in turn influence carrier concentration and dynamics in the channel due to modulation of Schottky barrier height and band-bending at the metal/semiconductor interface.

A novel rectangular shape differential CMOS split-drain Hall Effect magnetic field-effect transistor (MAGFET) was designed and fabricated employing a CMOS 0.5 μm process. The detection and monitoring of single 2.8 μm diameter magnetic beads was successfully performed using this MAGFET design. Based on the device modeling, simulation and the signal to noise ratio analysis, it was found that the optimal sensitivity can be achieved when the MAGFET channel width to length ratio is equal to 1.3. Further, it is shown through that when the MAGFET is scaled down, its SNR performance can sustain its peak, while being more sensitive to the geometry variations.

A novel circular CMOS MAGFET (Magnetic Field Effect Transistor) design is introduced and a novel device geometry design methodology is proposed to optimize the magnetic particle detection sensitivity of such devices. In order to optimize the signal to noise ratio, it was determined that the geometry of the MAGFET is required to have specific ratios, where its sector angle θ and its inner and outer radii r1 and r2 are optimized when θ/ln(r2/r1) = 1.3 . Compared to the more traditional rectangular MAGFET, the circular MAGFET has compatible SNR peak performance with rectangular MAGET. However, when the size of the MAGFET is scaled down in order to detect smaller magnetic particles, the proposed circular MAGFET has more robust SNR performance, design flexibility and tolerance to processing variations.

In this work, a noise measurement of capacitive micro-accelerometers incorporating temperature effect is presented. In the setup, a hot plate is used to heat the device up to temperatures in the 75 degree C range. A thermo couple attached to the enclosure is used to assess its temperature. The data show that the noise power increases at high temperature, but not as significant as predicted by the theory.

A binary detector with hysteresis-type nonlinearity is investigated. The detector is proposed as a suboptimal solution for a bit rate transparent midspan repeater in all optical networks. It is shown that key computations for the bit error rate are reduced to the well-known "exit problem" of stochastic differential equation theory. This formalism is employed to derive closed form expressions in the transform domain for the probability density function of the detector output in the presence of additive noise. Applying inverse transformations, these expressions can be utilized to determine various performance measures of binary detectors with hysteresis.

Numerical simulation results for the spectral density of noise due to current fluctuations are presented. The mathematical framework is based on the interpretation of the equations describing electron transport in the semiclassical transport model as stochastic differential equations (SDE). Within this framework, it was previously shown that the autocovariance function of current fluctuations can be obtained from the transient solution of the Boltzmann transport equation (BTE) with special initial conditions. The key aspect which differentiates this approach from other noise models is that this approach directly connects noise characteristics with the physics of scattering in the semiclassical transport model and makes no additional assumptions regarding the nature of noise. The solution of the BTE is based on the Legendre polynomial method. A numerical algorithm is presented for the solution of the transient BTE. Numerical results are in good agreement with Monte Carlo noise simulations for the spectral density of current fluctuations in bulk silicon.

Numerical simulation results of noise due to current fluctuations along an n+−n−n+ submicron structure are presented. The mathematical framework is based on the interpretation of the equations describing electron transport in the semiclassical transport model as stochastic differential equations (SDE). According to this formalism the key computations for the spectral density describing the noise process are reduced to a special initial value problem for the Boltzmann transport equation (BTE). The algorithm employed in the computation of the space dependent noise autocovariance function involves two main processes: the stationary self-consistent solution of the Boltzmann and Poisson equations, and a transient solution of the BTE with special initial conditions. The solution method for the BTE is based on the Legendre polynomial method. Noise due to acoustic and optical scattering and the effects of nonparabolicity are considered in the physical model.

A flexible technology is proposed to integrate smart electronics and microfluidics all embedded in an elastomer package. The microfluidic channels are used to deliver both liquid samples and liquid metals to the integrated circuits (ICs). The liquid metals are used to realize electrical interconnects to the IC chip. This avoids the traditional IC packaging challenges, such as wire-bonding and flip-chip bonding, which are not compatible with current microfluidic technologies. As a demonstration we integrated a CMOS magnetic sensor chip and associate microfluidic channels on a polydimethylsiloxane (PDMS) substrate that allows precise delivery of small liquid samples to the sensor. Furthermore, the packaged system is fully functional under bending curvature radius of one centimetre and uniaxial strain of 15%. The flexible integration of solid-state ICs with microfluidics enables compact flexible electronic and lab-on-a-chip systems, which hold great potential for wearable health monitoring, point-of-care diagnostics and environmental sensing among many other applications.

This review article summarizes our work during the past five years on a new approach to the modeling of aftereffect phenomena in hysteretic systems, This approach is based on Preisach type models driven by stochastic inputs. Both the classical and nonlinear Preisach models are employed in this approach. Thermal perturbations which result in the gradual loss of memory in hysteretic systems are modeled by discrete and continuous time stochastic inputs. The important properties of the aftereffect model are highlighted and compared with the traditional thermal activation type models and with some known experimental facts.

This paper presents a new approach to model hysteresis and aftereffect phenomena. A dynamic approximation of rectangular hysteresis loops is employed that leads to the representation of the input-output relationship as a first-order dynamical system driven by white noise. Closed-form expressions are derived for the output of rectangular loops in terms of convolution-type integrals. The formalism allows one to circumvent some of the mathematical challenges associated with history-dependent switching of rectangular hysteresis loops driven by stochastic processes.

This paper presents a new parallel-in-time algorithm for the two dimensional transient simulation of SOI devices. With this approach, simulation in both space and time domains is performed in parallel As a result, the CPU time is reduced significantly from the conventional serial-in-time method. This new approach fully exploits the inherent parallelism of the finite difference formulation of the basic semiconductor device equations and the massively parallel architecture of SIMD computers. The space domain computations are inherently parallel due to the nature of our technique of solving the finite-difference equations. Time domain parallelism is achieved by shifting the potentials from previous time points to subsequent points one-step forward along the time axis with each Gummel iteration. This algorithm employs a fixed-point iteration technique, therefore a direct solution of matrix equations is avoided. The algorithm is especially suitable for the transient simulation of SOI devices that exhibit transient drain current overshoot. Numerical experiments show that the new parallel-in-time method is up to eight times faster than the conventional serial-in-time method in SOI transient simulations. The program is coded in CM Fortran for the Connection Machine. >

Preisach models driven by stochastic inputs are employed to model magnetic aftereffect in the presence of demagnetizing fields. As a result of thermal relaxation, the magnetization and, consequently, the demagnetizing field vary in time. The new model generalizes earlier work and self-consistently accounts for the effect of time varying demagnetizing fields on the relaxation process. Three practical numerical techniques are proposed to compute the time variation in the magnetic field and the state of the Preisach plane.

MEMS accelerometers are extensively employed in various consumer applications due to their rapidly decreasing costs. In order to meet the low-cost requirements, manufacturers are forced to sacrifice some design parameters that may degrade their accelerometers' reliabilities. Interestingly, there is not much published works on the reliability aspects of MEMS accelerometers. Two reports detailed the reliability qualitative assessment on commercial devices [1–2]. Both works concluded that MEMS accelerometers are high reliable devices with low failure rates. In a recent study [3], a procedure to perform the quantitative accelerated life testing (QALT) on tri-axis accelerometer from STM was proposed, with a crude setup to vary the accelerations and temperatures. The purpose of this paper is to employ the QALT procedure on single axis accelerometers from Analog Device and Freescale. Laser-precision apparatus was designed, built, and employed to provide three types of excitations with great accuracy; mechanical (gravitational) test, thermal test and acoustical test. These tests are designed to mimic the operating conditions of the system, where the devices are employed.

Simulation results are presented for a MOSFET with position- and energy- (potential-) dependent interface trap distributions that may be typical for devices subjected to interface-trap-producing processes such as hot-electron degradation. The interface-trap distribution is modeled as a Gaussian peak at a given position along the channel, and the energy dependence is derived from C-V measurements from an MOS capacitor exposed to ionizing radiation. A novel fixed-point technique is used to solve the two-dimensional boundary-value problem. The technique is shown to be globally convergent for arbitrary distributions of interface traps. A comparison of the convergence properties of the Newton and fixed-point methods is presented, and it is shown that for some important cases the Newton technique fails to converge while the fixed-point technique converges with a geometric convergence rate. >

The authors performed the low frequency noise measurement (LFNM) technique to study noise characteristics of commercial accelerometers with single and dual axis. In this work, we studied the noise characteristics of a three-axis accelerometer using an improved and sensitive test setup to avoid cross-axis distortion.

Recently, several aftereffect models were proposed in which Preisach type hysteresis transducers are driven by stochastic inputs. Such inputs represent random thermal perturbations which are the source of the aftereffect phenomenon. According to these models, aftereffect is completely characterized by the magnetization history, the Preisach function and noise parameters. In this article, we present an identification of model parameters in which temperature-dependence is incorporated into the aftereffect model. The temperature variation of the noise parameters are investigated in order to predict the aftereffect decay coefficient. Comparison of numerical results with experimental ones observed in metal particle tape (MPT) magnetic recording media show a good agreement. As a result, based on the magnetization history, the Preisach function and noise parameters, it is shown that the model can be used to predict aftereffect characteristics of magnetic recording media of arbitrary magnetization history and temperature.

Previously, several aftereffect models were proposed in which Preisach type hysteresis transducers are driven by stochastic inputs. Such inputs model random thermal perturbations which are the source of aftereffect phenomena. In this article, we compare experimental and numerical simulation results for the first time in order to verify the proposed models, and present an identification procedure to determine aftereffect model parameters. Numerical simulations of the aftereffect model show the well known log t-type decay in magnetization whose rate reaches a maximum near the coercive field. Comparison of these with experimental results from /spl gamma/-Fe/sub 2/O/sub 3/ recording media show excellent agreement. Based on this comparison, we propose a practical procedure to identify the stochastic parameters of the aftereffect model.

Previously, it has been shown that Preisach type models driven by stochastic inputs can be employed to model aftereffect. In this model, the machinery of the "exit problem" is instrumental in computing the time evolutions of the expected value and the distributions of switching times. Here, for the first time, we present numerical simulation results of the aforementioned viscosity models and demonstrate that these models can be employed to compute switching times and time evolutions of the expected value of magnetization.

In a previous work, it has been suggested to use the Preisach model driven by stochastic inputs as a model for aftereffect. Here, we further extend this approach by employing the more accurate nonlinear input dependent Preisach model. The time evolution of the expected value of the output (magnetization) is derived in terms of the stochastic description of the input. It is shown that the mathematical machinery of the "exit problem" is instrumental for calculations of time evolutions of the expected value of the output of the nonlinear input dependent Preisach model. >

The authors had previously proposed the use of the classical Preisach model driven by stochastic inputs as a model of viscosity in hysteretic systems. Here, this approach is extended by utilizing the nonlinear (input dependent) Preisach model of hysteresis. This model is more general than the classical Preisach model, but its treatment encounters some technical difficulties. As a useful by-product, the authors investigate the viscosity phenomenon in Stoner-Wohlfarth-type particles. >

This review provides a comprehensive survey of noise research in MEMS. Some background on noise and on MEMS is provided. We review noise production mechanisms, and highlight work on the theory and modeling of noise in MEMS. Then noise measurements in the specific types of MEMS are reviewed. Inertial MEMS (accelerometers and angular rate sensors), pressure and acoustic sensors, optical MEMS, RF MEMS, surface acoustic wave devices, flow sensors, and chemical and biological MEMS, as well as data storage devices and magnetic MEMS, are reviewed. We indicate opportunities for additional experimental and computational research on noise in MEMS.