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In this work, we demonstrate pH sensing using the out-of-equilibrium body potential (V B) monitored in silicon-on-insulator (SOI) double-gate "ISFET-like" devices with deposited metal contacts. Similar to the behavior of a dual-gate ISFET, in this study, the conductive channel induced by the back-gate voltage at the silicon/buried oxide (Si/BOX) interface is modulated by the charges to-be-sensed that are intentionally placed on the top silicon oxide layer SiO 2 covering the Si film. The detection of the surface charge modulation was evidenced by monitoring in real-time the out-of-equilibrium body potential, while the classic shift in the drain current served as control experiment and for benchmarking. These first experiments demonstrate the successful implementation of this new pH detection paradigm, with super-Nernstian sensitivity. To provide optimization options for the body-potential sensing, TCAD simulations of the pH sensors were performed in a 2D structure and illustrated the possibility to further enhance the device sensitivity with an optimized architecture. Moreover, the pH-induced shift occurs at very high applied gate biases for the drain current, contrary to the body potential, which implies a sensor with lower power consumption when V B is used as reading method. Thus, body potential monitoring provides a promising reading method to reach the required low-power consumption regime of the tomorrow's sensing devices. [Display omitted] • Out-of-equilibrium body potential, a new dynamic reading method with ISFET-like devices. • Super-Nernstian response in Silicon-On-Insulator sensors with deposited metal contacts. • Fabrication of ISFETs for "in-liquid" detection based on the out-of-equilibrium body potential. • Sensitivity investigation of ISFET sensors through TCAD simulations. • Benchmark of sensing: out-of-equilibrium body potential versus drain current method. [ABSTRACT FROM AUTHOR]

This work addresses the origin of the transient body potential variation in silicon on insulator (SOI) with deposited metal contacts, under back-gate bias sweep from accumulation to inversion. The phenomenon arises from the difficulty to inject carriers into the silicon film due to the Schottky contact between the metal and the low p-type doped silicon. The Schottky diode current is controlled by the back-gate voltage, which fixes the potential at the bottom of the low-doped film. When the back-gate voltage drives the silicon film towards inversion, the limited current from the Schottky contact induces a deficit of minority carriers in the film and brings the body potential in an out-of-equilibrium regime. This phenomenon will be reproduced with numerical modelling based on Poisson and continuity equations, including the quasi-Fermi potential. The transient character and its dependence on the Schottky barrier height will be evidenced. A simple and effective combination of the classic Schottky current equation and inversion current calculated from the Lambert function, as in fully depleted (FD)-SOI MOSFETs, confirms the origin of the effect. [ABSTRACT FROM AUTHOR]

In this paper, we applied the out-of-equilibrium body potential measurements in a silicon-on-insulator (SOI) structure as a mean of DNA detection. The biochips were manufactured by 3-glycidoxypropyltrimethoxysilane (GOPTMS) functionalization, and single stranded DNA probes corresponding to human papillomavirus (HPV) were grafted onto the surface. The physicochemical characteristics were assessed by contact angle, Fourier Transform Infrared Spectrometry (FTIR) and microarray technique. The effects of the bio-chemical attachments to the surface of SOI were evaluated by body potential measurements implemented in the $\Psi $ -MOSFET configuration, typically used for electrical characterization of substrates. Body potential measurements versus the back gate voltage were able to distinguish the shift induced by DNA molecules only and the signatures were related to target DNA concentrations. The proposed reading method is remarkable owing to the fact that (1) it measures a potential (in the order of 1V) instead of a low current, (2) it allows fast sweeping measurements and (3) it requires a gate voltage close to 0V which induces less stress on the molecules attached to the surface. [ABSTRACT FROM AUTHOR]

This article focuses on one of the floating body effects in silicon-on-insulator (SOI) substrates, the out-of-equilibrium body potential. Unlike the already existing studies which explore either SOI fully fabricated devices or SOI wafers measured with pressure probes, here the out-of-equilibrium body potential is explored in SOI substrates with deposited metal contacts. Chromium and gold/titanium contacts of various geometries were deposited on silicon films of SOI and the floating body potential was examined in each case. The effect of annealing on the device behavior was also investigated. The performance of the deposited metal contacts is evaluated through current and potential monitoring under quasi-static conditions. Depending on the workfunction difference between metal and silicon film, the current measurements show that the contact behavior is mainly ohmic-like or Schottky-like. While body potential manifests itself with Schottky-like contacts, it does not seem to exhibit a significant response with ohmic contacts. The influence of the contact architecture on the body potential signature is illustrated, enabling the selection of the proper contact layout for an enhanced body potential response. [ABSTRACT FROM AUTHOR]

The floating‐body effects (FBEs) are widely documented in the history of silicon on‐insulator (SOI) transistors. The interest herein is threefold: 1) FBEs are revisited in the context of advanced fully depleted SOI with a thickness below 25 nm; 2) direct measurements of floating‐body potential enable in‐depth interpretation; and 3) additional evidence for the role of supercoupling is given. The typical consequences of FBEs (kink effect, parasitic bipolar transistor, transient and hysteresis in drain current, and metastable dip) are investigated and discussed. The critical roles of back‐gate biasing, body thickness, and frequency in the activation of FBEs are outlined. The signature of FBEs is still present in 12–25 nm films but disappears in sub‐10 nm‐thick transistors, due to the supercoupling effect. [ABSTRACT FROM AUTHOR]

For partially depleted (PD) silicon-on-insulator (SOI) technology, body contact technology, such as T-gate (TB) body contact, is often used to suppress the floating body effect for analog or radio frequency (RF) circuits. RF performance is usually measured using a two-port network with body node connected to source node, thereby limiting the potential applications of PD SOI technology. In this letter, a four-port network structure was used for TB SOI MOSFET to evaluate the influence of the body potential on the RF performance. The gate to source and body capacitance were also extracted, individually. It was found that TB device can have an 89% improvement in the cut-off frequency ( fT ) by tuning the body voltage to 0.5 V when the device was operated at gate voltage equals to 0.4 V and drain voltage equals to 0.3 V. Power dissipation reduction was also observed with forward body bias and lower drain voltage. The results indicate that four-port network structure has potential in RF modeling for PD SOI technology that could facilitate integrating the PD SOI process into low power applications. [ABSTRACT FROM PUBLISHER]

Systematic experiments demonstrate the presence of the kink effect even in FDSOI MOSFETs. The back-gate bias controls the kink effect via the formation of a back accumulation channel. The kink is more or less pronounced according to the film thickness and channel length. However, in ultrathin (<10 nm) and/or very short transistors (L < 50 nm), the kink is totally absent as a consequence of super-coupling effect. For the first time, thanks to the availability of body contacts, the body potential is probed to evidence the impact of majority carrier accumulation and drain pulse duration on the kink effect onset. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the out-of-equilibrium body potential behaviour in the Ψ-MOSFET configuration. Consistent measurements in this experimental setup succeeded in providing a substantial understanding of its characteristics in the depletion region. The final objective of this work is to envision this new measurement technique for biochemical sensor applications. Among its advantages, the most important are its simplicity, the good sensitivity, the measurement of a potential instead of a current and the low bias needed for detection compared to the conventional drain current measurements. [ABSTRACT FROM AUTHOR]

This paper presents the evaluation of a capacitance matrix and the temporal body potential of an artificial orbiting satellite considering a metallic cuboid, parabolic reflector antennas, and solar panels. Integral equations are formed by relating the unknown charge density on the metallic conductor and are solved using the method of moments, in which the pulse functions are used as basis functions and the delta functions are used as testing functions. The surfaces of the conducting structure are meshed using nonuniform triangular subareas. The matrix equations are solved using an iterative generalized minimum residual algorithm. The numerical data on the capacitance matrix and the charge distribution of these structures have been presented. The validity of this analysis has been established by comparing the data on capacitance available in the literature for the metallic cuboid with the data on capacitance computed by the present method for similar structures. The temporal behavior of body potential of the satellite is computed for different cases. [ABSTRACT FROM PUBLISHER]

The impact of total ionizing dose (TID) is reported on irradiated capacitorless metastable dip RAM (MSDRAM) cells, built in a planar SOI technology. The memory window shifts toward more negative voltages at higher doses. The unconventional gate current peak measured in MSDRAM cells decreases with dose and disappears at 500~\ krad(\ SiO2) for these devices. The retention time of the 0-state decreases with dose, with the greatest decrease for memory cells programmed with high back-gate voltages. The trapped charge in the 400-nm buried oxide changes the potential in the body and interferes with the ability to store a 0-state. The irradiated cells exhibit higher drain currents while reading the 1-state. This increase of the drain current is enhanced for longer programming times. [ABSTRACT FROM AUTHOR]

Abstract: Even in fully-depleted (FD) SOI MOSFETs, the floating-body potential variations may lead to strong transient effects on the current characteristics. A physics-based model, enabling the fast computing of the potential variation with time, is proposed in this paper. The model is validated, for a wide range of technological parameters and biases, by 2D numerical simulations. This model reproduces the experimental data and clarifies the physics mechanisms responsible for the transient variations of gate and drain currents. Relevant applications in the field of EEPROM and capacitorless floating-body DRAM memories are addressed. [Copyright &y& Elsevier]

Abstract: A detailed analysis of the body potential impact on the performance enhancement of Body Contacted (BC) pMOSFET when the body is not grounded, is reported in this paper. Investigations on BC pMOSFET with a floating-body configuration reveal that this new floating-body effect leads to pMOSFET drive capability increase with higher transconductance, lower subthreshold slope, no off-state leakage current degradation and no kink effect. The body potential is mainly controlled by the electron tunneling from the conduction band (ECB) between the partial n+ poly-gate and the n type silicon substrate through the 1.6nm thin gate oxide. Static characterizations of various layouts and geometries demonstrate that narrow pMOSFET and H-gate design provides the highest Ion gain due to higher body potential. Furthermore, it has been found that the largest n+ poly-gate area results in the fastest switch-on drain current transients. [Copyright &y& Elsevier]

Abstract: We present in this work a study of the linear kink effect (LKE) occurrence in partially depleted (PD) SOI nMOSFETs with thin gate oxide. The experimental LKE dependence on the channel length, channel width and drain voltage are reported as well as the impact of various parameters on the second peak has been studied by two-dimensional numerical simulations, namely, the gate current level, the carrier lifetime, the increase of the body potential, the threshold voltage variation and AC analysis. Three-dimensional simulations were also performed in order to evaluate the LKE dependence on the channel width. [Copyright &y& Elsevier]

Abstract: The process of electrification of the human body by walking on resistive floors has been analysed and the corresponding body potential measured. A model for electric body potential caused by walking has been proposed and then verified experimentally. The model combines two main processes: an exponential increase of potential due to successive charging and potential oscillations caused by periodic changes of body capacitance during walking. The conditions for initiation of Paschen''s microdischarges running in the gaps between floor and soles of walker''s footwear have been specified and a corresponding relation for minimum saturated body potential causing Paschen''s discharges has been derived. This saturated critical potential has been found to be much higher than that usually attained by walking on common floors which explains why the Paschen discharges did not appear in such air gaps. On the other hand, the microdischarges developed between uncovered parts of the human body and grounded metallic objects have been found to be likely even with common floor and sole materials. [Copyright &y& Elsevier]