A novel design of a MEMS (Micro-Electromechanical System) capacitive accelerometer fabricated by surface micromachining, with a structure enabling precise auto-calibration during operation, is presented. Precise auto-calibration was introduced to ensure more accurate acceleration measurements compared to standard designs. The standard mechanical structure of the accelerometer (seismic mass integrated with elastic suspension and movable plates coupled with fixed plates forming a system of differential sensing capacitors) was equipped with three movable detection electrodes coupled with three fixed electrodes, thus creating three atypical tunneling displacement transducers detecting three specific positions of seismic mass with high precision, enabling the auto-calibration of the accelerometer while it was being operated. Auto-calibration is carried out by recording the accelerometer indication while the seismic mass occupies a specific position, which corresponds to a known value of acting acceleration determined in a pre-calibration process. The diagram and the design of the mechanical structure of the accelerometer, the block diagram of the electronic circuits, and the mathematical relationships used for auto-calibration are presented. The results of the simulation studies related to mechanical and electric phenomena are discussed.

Field-effect transistors (FETs) are efficient detectors of THz radiation. Despite over three decades of research, controversy still exists regarding the detection mechanism. The article attempts to solve this problem systemically. Existing approaches to modeling THz detection are critically reviewed, including plasmonic, resistive mixing, hot carrier and thermal models. Limitations and inconsistencies of the first two approaches, along with some classical physics principles and experiments conducted, were identified. These include the facts that some models were formulated independently of material relaxation time constraints, and the plasmonic approach does not take into account the conditions for the formation of surface plasmon-polarons and does not describe the case of p-type devices (hole plasmons have never been experimentally recorded). Relevant measurements and theoretical considerations illustrate the inadequacy of these models. As a result of this analysis, thermoelectric models are expected to explain THz sensing by FETs.

The semiconductor industry continues to grow and innovate; however, companies are facing challenges in growing their workforce with skilled technicians and engineers. To meet the demand for well-trained workers worldwide, innovative ways to attract skilled talent and strengthen the local semiconductor workforce ecosystem are of utmost importance. FOSS CAD/EDA tools combined with free and open-access PDKs can serve as a new platform for bringing together IC design newbies, enthusiasts, and experienced mentors.

We present a review of compact models of THz radiation detection in MOSFETs, based on plasmon excitation, resistive mixing and thermionic emission. The model assumptions and limitations, advantages and shortcomings, as well as main steps, and results are discussed taking into account a pretty broad review of the literature.

This paper discusses the multi-domain modeling and simulation issues of the design and analysis of heterogeneous integrated systems. Modeling and simulation method- ology and tools are also discussed.

Three sensors for chemical and physical examination of aqueous solutions were presented in the paper. An Au potentiometric electrode, an AgCl chlorine ion sensor and a p-n junction thermometer were developed. Their layout and internal structure were explained in the light of the manufacturing process. The device characteristics were measured in conditions corresponding to normal operation of the devices. Basic electrical parameters of the developed structures, as well as their sensitivity to environmental parameter variation were estimated.

Extensive numerical simulations of FinFET structures have been carried out using commercial TCAD tools. A series of plasma etching steps has been simulated for different process conditions in order to evaluate the influence of plasma pressure, composition and powering on the FinFET topography. Next, the most important geometric parameters of the FinFETs have been varied and the electrical characteristics have been calculated in order to evaluate the sensitivity of the FinFET electrical parameters on possible FinFET structure variability.

The paper describes the results of a study on p-type field effect transistors working as detectors of THz radiation. The p-type Junctionless FETs and MOSFETs were fabricated. They were tested in a 316 -360 GHz EM radiation band. Their responsivity and S/N ratio were measured and compared with the parameters of the n-type FETs. It was found that the photoresponse characteristics vs. gate bias were analogous to the n-type FET detectors, but with the difference that the p-FET photoresponse is positive and the n-FET signal one is negative.

Silicon junctionless field-effect transistors (JLFETs) detect THz radiation even at frequencies above a few THz. This effect cannot be explained by classic laws of electron transport. The same behavior is observed for other types of FETs. However, the JLFET architecture makes this device an effective tool for testing the THz detection mechanism. In particular, a deeper insight into this effect is provided by a case study in which, the low concentration of electrons in the gate-controlled region contradicts potential plasmonic effects. Considering the experimental results, the authors critically discuss the plasmon-based theory of THz detection by JLFETs. Then, taking into account the revealed inconsistencies and based on numerical simulation results, they propose a simple, one-dimensional JLFET photoresponse model based on local electron heating at the channel–source contact which is located in the path of the THz signal between the gate and the source. The model is verified in a simulation-assisted experiment showing that the energy of hot electrons generates a sufficient photoelectric voltage, typical of silicon FETs integrated with antennas illuminated by THz radiation. The authors suggest that the model is universal and in the three-dimensional version it can successfully explain the THz detection by various FETs, especially those operating in the subthreshold range in which the electron concentration under the gate is very low.

The microelectronics and nano-electronics industry strongly relies on compact models to reduce a new microelectronic product development costs. The goals of this review are to highlight critical issues for the development of compact models for microelectronics and nano-electronics. In this chapter, we’ve covered the main principles of the compact device modeling. Also discussed are the possibilities of integrating compact models into circuit simulation and design tools, with an emphasis on the Verilog-A standardization, which simplify model implementation into EDA tool.

The paper presents our works on the measurement and characterization of two types of field-effect transistors (FETs) used for efficient detection of THz radiation: standard MOSFETs manufactured in a CMOS process on Si and SOI substrates and junctionless field-effect transistors (JLFETs) on SOI wafers. Based on the measurement results, we critically review and discuss the validity of the existing models: plasmonic and resistive mixing. The conclusions open space for further studies on the THz detection mechanism and on modeling this effect.

Schematic capture is an important and popular front-end for circuit simulation. It provides users with a flexible tool that allows circuit diagrams to be drawn and automati-cally converted into textual circuit netlists. Conventional SPICE simulators are essentially engines that input circuit data and simulation command netlists, undertake simulation, and output data for post-processing. This paper is concerned with an advance in circuit schematic capture functionality which allows both SPICE netlists and Verilog-A module code to be simultaneously generated from a device model or circuit schematic. This de-velopment, particularly when combined with SPICE behavioural device modelling, allows automatic generation of Verilog-A device modules rather than going through the manual conversion process from SPICE netlists to Verilog-A code modules. To demonstrate the validity of the reported advances in Qucs-S/Xyce schematic capture a behavioural model and a Verilog-A module for a GaAs MESFET are presented, and their performance described.

A new approach to an analysis of the operation of a “black box” device generating a DC output signal is presented. The signal is measured using a lock-in in voltage and current modes. A measured small frequency output admittance is used to develop an equivalent circuit of the device. The method allows for conclusions on a sensor internal structure and operation principles. It is illustrated by analysis of the operation of a SOI JLFET THz radiation sensor.

Micromechanical cantilevers are attractive devices for force measurements. We report the results obtained for SMMM (Soft MetMoIMEMS) silicon cantilever fabricated on silicon on insulator (SOI) substrate with piezoresistive deflection readout with the stiffness much lower than the typical piezoresistive silicon cantilever. The cantilever mechanical properties were characterised with laser vibrometer using the thermal noise technique (resonant frequency f(res) = 5474.2 Hz, quality factor Q = 19.4 and stiffness k = 0.042 Nm(-1)). The piezoresistive detection sensitivity was evaluated by measuring externally induced mechanical vibrations optically with laser vibrometer and electrically using current-to-voltage converter and lock-in amplifier simultaneously. We obtained deflection sensitivity DS = 11 Vm(-1) and force sensitivity FS = 263 VN-1 assuming typical bias voltage of 2 V. Such silicon cantilever may be successfully used in AFM investigation of fragile structures. (C) 2019 Elsevier B.V. All rights reserved.

A new type of JLFET based detector is described in the paper. This JLFET is equipped with additional electrode contacting side of the channel (giving T-like shape of the channel). The device offers higher photoresponse and better SNR and NEP than its standard counterpart. The most promising for application is -0.5 V.. 0 V gate voltage range, where 84 dB SNR is noted.

The EKV2.6 MOSFET compact model has had a considerable impact on the academic and industrial community of analog integrated circuit design, since its inception in 1996. The model is available as a free open-source software (FOSS) tool coded in Verilog-A. The present paper provides a short review of foundations of the model and shows its capabilities via characterization and modeling based on a test chip in 180 nm CMOS fabricated via Europractice.

The EKV2.6 MOSFET compact model has had a considerable impact on the academic and industrial community of analog integrated circuit design, since its inception in 1996. The model is available as a free open-source software (FOSS) tool coded in Verilog-A. The present paper provides a short review of foundations of the model and shows its capabilities via characterization and modeling based on a test chip in 180 nm CMOS fabricated via Europractice.

An application of the drain current vs substrate bias characteristics of MOSFETs for the device parameter extraction is presented. Modeling of the substrate bias effect on the MOSFET drain current is briefly discussed. A method of the MOSFET characterization is formulated. It requires a measurement of two I(V) characteristics, including the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> ) smooth curve measured in a "sweep" mode. The method allows to extract the threshold voltage parameters and to estimate the in-depth doping profile in the substrate. The proposed approach is demonstrated using I(V) data of the MOSFETs manufactured in ITE in a bulk CMOS process.

Two models of the THz electromagnetic radiation detection using field-effect devices are presented and briefly discussed with regard to junctionless FETs as THz detectors. Due to inconsistency between a plasmonic theory and JLFET characteristics, a resistive mixing approach has been considered in a more detail and adopted for interpretation of the JLFET THz photoresponse. Fabrication of the test JLFETs and their electrical characterization are described. The detector channel conductance model and the photoresponse model have been developed in accordance with the resistive mixing theory. The modeling results are verified based on the experimental results of the THz detection using test devices.

It is well known that integration of THz detectors with silicon lenses (made of high-resistive Si) brings several advantages including a significant increase of the detector responsivity due to the increased aperture of the detector. THz detectors manufactured in CMOS technology are based usually on a n-type sensing transistor monolithically integrated with an antenna fabricated in the same process sequence. Integration of such a detector with Si lens is not an easy task. The simplest way is to introduce the THz radiation through the silicon lens glued to the substrate, which then has to be made (if possible) of high-resistive silicon to avoid energy losses. Following results of several experiments described in this paper our CMOS process sequence has been modified both with respect to the substrate change and then maximizing of the antenna efficiency by removal of heavily doped areas of the channel stopper in its vicinity