The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa(-1), a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications.

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Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

This paper describes the latest and most advanced surface-potential-based model jointly developed by The Pennsylvania State University and Philips. Specific topics include model structure, mobility and velocity saturation description, further development and verification of symmetric linearization method, recent advances in the computational techniques for the surface potential, modeling of gate tunneling current, inclusion of the retrograde impurity profile, and noise sources. The emphasis of this paper is on incorporating the recent advances in MOS device physics and modeling within the compact modeling context

PSP: An Advanced Surface-Potential-Based MOSFET Model for Circuit Simulation

Foreword. Preface. List of Symbols. 1. Introduction. 1.1 The Importance of Device Modeling for IC Design. 1.2 A Short History of the EKV MOST Model. 1.3 The Book Structure. PART I: THE BASIC LONG-CHANNELINTRINSIC CHARGE-BASED MODEL. 2. Introduction. 2.1 The N-channel Transistor Structure. 2.2 Definition of charges, current, potential and electric fields. 2.3 Transistor symbol and P-channel transistor. 3. The Basic Charge Model. 3.1 Poisson's Equation and Gradual Channel Approximation. 3.2 Surface potential as a Function of Gate Voltage. 3.3 Gate Capacitance. 3.4 Charge Sheet Approximation. 3.5 Density of Mobile Inverted Charge. 3.6 Charge-Potential Linearization. 4. Static Drain Current. 4.1 Drain Current Expression. 4.2 Forward and Reverse Current Components. 4.3 Modes of Operation. 4.4 Model of Drain Current Based on Charge Linearization. 4.5 Fundamental Property: Validity and Application. 4.6 Channel Length Modulation. 5. The Small-Signal Model. 5.1 The Static Small-Signal Model. 5.2 A General Non-Quasi-Static Small-Signal Model. 5.3 The Quasi-Static Dynamic Small-Signal Model. 6. The Noise Model. 6.1 Noise Calculation Methods. 6.2 Low-Frequency Channel Thermal Noise. 6.3 Flicker Noise. 6.4 Appendices. Appendix : The Nyquist and Bode Theorems. Appendix : General Noise Expression. 7. Temperature Effects and Matching. 7.1 Introduction. 7.2 Temperature Effects. PART II: THE EXTENDED CHARGE-BASED MODEL. 8. Non-Ideal Effects Related to the Vertical Dimension. 8.1 Introduction. 8.2 Mobility Reduction Due to the Vertical Field. 8.3 Non-Uniform Vertical Doping. 8.4 Polysilicon Depletion. 8.4.1 Definition of the Effect. 8.5 Band Gap Widening. 8.6 Gate Leakage Current. 9. Short-Channel Effects. 9.1 Velocity Saturation. 9.2 Channel Length Modulation. 9.3 Drain Induced Barrier Lowering. 9.4 Short-Channel Thermal Noise Model. 10. The Extrinsic Model. 10.1 Extrinsic Part of the Device. 10.2 Access Resistances. 10.3 Overlap Regions. 10.4 Source and Drain Junctions. 10.5 Extrinsic Noise Sources. PART III: THE HIGH-FREQUENCY MODEL. 11. Equivalent Circuit at RF. 11.1 RF MOS Transistor Structure and Layout. 11.2 What Changes at RF?. 11.3 Transistor Figures of Merit. 11.4 Equivalent Circuit at RF. 12. The Small-Signal Model at RF. 12.1 The Equivalent Small-Signal Circuit at RF. 12.2 Y-Parameters Analysis. 12.3 The Large-Signal Model at RF. 13. The Noise Model at RF. 13.1 The HF Noise Parameters. 13.2 The High-Frequency Thermal Noise Model. 13.3 HF Noise Parameters of a Common-Source Amplifier. References. Index.

Charge-Based MOS Transistor Modeling - The EKV Model for Low-Power and RF IC Design

Revisiting MOSFET threshold voltage extraction methods

This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

This paper examines the relation between the structure of a compact MOSFET model and its ability to model harmonic distortion. It is found that non-singular behavior at zero drain bias is essential for qualitatively correct simulations of the third harmonic power dependence. Specifically, nonlinear distortion analysis requires that the Gummel symmetry condition be satisfied by the compact model. A simple procedure to enforce the Gummel symmetry without increasing the complexity of the model is incorporated in an advanced surface-potential-based MOSFET model to enable correct harmonic distortion modeling.

RF distortion analysis with compact MOSFET models

The constant-current (CC) method uses a current criterion to determine the threshold voltage (VTH) of metal-oxide-semiconductor (MOS) field-effect transistors. We show that using the same current criterion in both saturation and linear modes leads to inconsistent results and incorrect interpretation of effects, such as drain-induced barrier lowering in advanced CMOS halo-implanted devices. The generalized adjusted CC method is based on the theory of the charge-based MOS transistor model. It introduces an adjusted current criterion, depending on VDS, allowing to coherently determine VTH for the entire range of VDS from linear operation to saturation. The method uses commonly available ID versus VG data with focus on moderate inversion. The method is validated with respect to the ideal surface potential model, and its suitability is demonstrated with technology-computer-aided-design data from a 65-nm CMOS technology and measured data from a 90-nm CMOS technology. Comparison with other widely used threshold voltage extraction methods is provided.

An Adjusted Constant-Current Method to Determine Saturated and Linear Mode Threshold Voltage of MOSFETs

This paper presents a simple and efficient analytical model of a MOS transistor-based pressure sensor. Starting from basic MOS equations, we derive a general relation between the gate transconductance and an equivalent gate capacitance that varies with pressure and whose definition represents a major improvement. Furthermore, such relation was found to be nearly independent of the MOS parameters and hence of the fabrication technology, in contrast with previous works. Results obtained with the present model are compared to two-dimensional (2D) simulations and model limitations are discussed in details.

Electrical modeling of a pressure sensor MOSFET

This paper presents a simple, physics-based, and continuous model for the quantum effects and polydepletion in deep-submicrometer MOSFETs with very thin gate oxide thicknesses. This analytical design-oriented MOSFET model correctly predicts inversion and depletion charges, transcapacitances, and drain current, from weak to strong inversion and from nonsaturation to saturation. One single additional parameter is used for polysilicon doping concentration, while the quantum correction does not introduce any new parameter. Comparison to experimental data of deep-submicrometer technologies is provided, showing accurate fits both for I-V and C-V data. The model offers simple relationships among effective electrical parameters and physical device parameters, providing insight into the physical phenomena. This new model thereby supports device engineering, analog circuit design practice, as well as efficient circuit simulation.

Accounting for quantum effects and polysilicon depletion from weak to strong inversion in a charge-based design-oriented MOSFET model

We discuss new developments of the compact EPFL-EKV charge based model for analog circuit simulations that are consistent with advanced CMOS technology. The physical foundations of the EKV model and in particular the normalization of the currents and charges are presented and their implications on the model structure are discussed. Based on the hierarchical model description, new effects such as poly gate depletion and quantum confinement can be simply considered as a model generalization. Finally, the consistency of the model is illustrated through the related RF derivation whose equivalent circuit, based on normalized transadmittances and frequencies, can be expressed as a combination of two generic functions only.

W. Grabinski

Papers

RF distortion analysis with compact MOSFET models

An Adjusted Constant-Current Method to Determine Saturated and Linear Mode Threshold Voltage of MOSFETs

Electrical modeling of a pressure sensor MOSFET

Accounting for quantum effects and polysilicon depletion from weak to strong inversion in a charge-based design-oriented MOSFET model

Advancements in dc and rf mosfet modeling with the epfl-ekv charge based model