Modeling of magnetic sensitivity of the metal-oxide-semiconductor field-effect transistor with double gates

In this paper, we investigated the effect of magnetic field on the carrier transport phenomenon in metal-oxide-semiconductor field-effect transistor (MOSFET) with double gates by examining the behavior of the semiconductor under the Lorentz force and a constant magnetic field. Various behaviors within the channel have been simulated including the potential distribution, conduction and valence bands, total current density, total charge density and the magnetic field. The results obtained indicate that this modulation affects the electrical characteristics of the device such as on-state current (ION), subthreshold leakage current (IOF), threshold voltage (VTh), and the Hall voltage (VH) is induced by the magnetic field. The change in threshold voltage caused by the magnetic field has been observed to affect the switching characteristics of the device, such as speed and power loss, as well as the threshold voltage VTh and (ION/IOF) ratio. Note that it is reduced by 10-3 V. 102 for magnetic fields of ±6 and ±5.5 tesla respectively

Caractérisation, mécanismes et applications mémoire des transistors avancés sur SOI

Ce travail présente les principaux résultats obtenus avec une large gamme de dispositifs SOI avancés, candidats très prometteurs pour les futurs générations de transistors MOSFETs. Leurs propriétés électriques ont été analysées par des mesures systématiques, agrémentées par des modèles analytiques et/ou des simulations numériques. Nous avons également proposé une utilisation originale de dispositifs FinFETs fabriqués sur ONO enterré en fonctionnalisant le ONO à des fins d'application mémoire non volatile, volatile et unifiées. Après une introduction sur l'état de l'art des dispositifs avancés en technologie SOI, le deuxième chapitre a été consacré à la caractérisation détaillée des propriétés de dispositifs SOI planaires ultra- mince (épaisseur en dessous de 7 nm) et multi-grille. Nous avons montré l excellent contrôle électrostatique par la grille dans les transistors très courts ainsi que des effets intéressants de transport et de couplage. Une approche similaire a été utilisée pour étudier et comparer des dispositifs FinFETs à double grille et triple grille. Nous avons démontré que la configuration FinFET double grille améliore le couplage avec la grille arrière, phénomène important pour des applications à tension de seuil multiple. Nous avons proposé des modèles originaux expliquant l'effet de couplage 3D et le comportement de la mobilité dans des TFTs nanocristallin ZnO. Nos résultats ont souligné les similitudes et les différences entre les transistors SOI et à base de ZnO. Des mesures à basse température et de nouvelles méthodes d'extraction ont permis d'établir que la mobilité dans le ZnO et la qualité de l'interface ZnO/SiO2 sont remarquables. Cet état de fait ouvre des perspectives intéressantes pour l'utilisation de ce type de matériaux aux applications innovantes de l'électronique flexible. Dans le troisième chapitre, nous nous sommes concentrés sur le comportement de la mobilité dans les dispositifs SOI planaires et FinFET en effectuant des mesures de magnétorésistance à basse température. Nous avons mis en évidence expérimentalement un comportement de mobilité inhabituel (multi-branche) obtenu lorsque deux ou plusieurs canaux coexistent et interagissent. Un autre résultat original concerne l existence et l interprétation de la magnétorésistance géométrique dans les FinFETs.L'utilisation de FinFETs fabriqués sur ONO enterré en tant que mémoire non volatile flash a été proposée dans le quatrième chapitre. Deux mécanismes d'injection de charge ont été étudiés systématiquement. En plus de la démonstration de la pertinence de ce type mémoire en termes de performances (rétention, marge de détection), nous avons mis en évidence un comportement inattendu : l amélioration de la marge de détection pour des dispositifs à canaux courts. Notre concept innovant de FinFlash sur ONO enterré présente plusieurs avantages: (i) opération double-bit et (ii) séparation de la grille de stockage et de l'interface de lecture augmentant la fiabilité et autorisant une miniaturisation plus poussée que des Finflash conventionnels avec grille ONO.Dans le dernier chapitre, nous avons exploré le concept de mémoire unifiée, en combinant les opérations non volatiles et 1T-DRAM par le biais des FinFETs sur ONO enterré. Comme escompté pour les mémoires dites unifiées, le courant transitoire en mode 1T-DRAM dépend des charges non volatiles stockées dans le ONO. D'autre part, nous avons montré que les charges piégées dans le nitrure ne sont pas perturbées par les opérations de programmation et lecture de la 1T-DRAM. Les performances de cette mémoire unifiée multi-bits sont prometteuses et pourront être considérablement améliorées par optimisation technologique de ce dispositif.The evolution of electronic systems and portable devices requires innovation in both circuit design and transistor architecture. During last fifty years, the main issue in MOS transistor has been the gate length scaling down. The reduction of power consumption together with the co-integration of different functions is a more recent avenue. In bulk-Si planar technology, device shrinking seems to arrive at the end due to the multiplication of parasitic effects. The relay has been taken by novel SOI-like device architectures. In this perspective, this manuscript presents the main achievements of our work obtained with a variety of advanced fully depleted SOI MOSFETs, which are very promising candidates for next generation MOSFETs. Their electrical properties have been analyzed by systematic measurements and clarified by analytical models and/or simulations. Ultimately, appropriate applications have been proposed based on their beneficial features.In the first chapter, we briefly addressed the short-channel effects and the diverse technologies to improve device performance. The second chapter was dedicated to the detailed characterization and interesting properties of SOI devices. We have demonstrated excellent gate control and high performance in ultra-thin FD SOI MOSFET. The SCEs are efficiently suppressed by decreasing the body thickness below 7 nm. We have investigated the transport and electrostatic properties as well as the coupling mechanisms. The strong impact of body thickness and temperature range has been outlined. A similar approach was used to investigate and compare vertical double-gate and triple-gate FinFETs. DG FinFETs show enhanced coupling to back-gate bias which is applicable and suitable for dynamic threshold voltage tuning. We have proposed original models explaining the 3D coupling effect in FinFETs and the mobility behavior in ZnO TFTs. Our results pointed on the similarities and differences in SOI and ZnO transistors. According to our low-temperature measurements and new promoted extraction methods, the mobility in ZnO and the quality of ZnO/SiO2 interface are respectable, enabling innovating applications in flexible, transparent and power electronics. In the third chapter, we focused on the mobility behavior in planar SOI and FinFET devices by performing low-temperature magnetoresistance measurements. Unusual mobility curve with multi-branch aspect were obtained when two or more channels coexist and interplay. Another original result in the existence of the geometrical magnetoresistance in triple-gate and even double-gate FinFETs.The operation of a flash memory in FinFETs with ONO buried layer was explored in the forth chapter. Two charge injection mechanisms were proposed and systematically investigated. We have discussed the role of device geometry and temperature. Our novel ONO FinFlash concept has several distinct advantages: double-bit operation, separation of storage medium and reading interface, reliability and scalability. In the final chapter, we explored the avenue of unified memory, by combining nonvolatile and 1T-DRAM operations in a single transistor. The key result is that the transient current, relevant for 1T-DRAM operation, depends on the nonvolatile charges stored in the nitride buried layer. On the other hand, the trapped charges are not disturbed by the 1T-DRAM operation. Our experimental data offers the proof-of-concept for such advanced memory. The performance of the unified/multi-bit memory is already decent but will greatly improve in the coming years by processing dedicated devices.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Wireless Sensors and Actuators for Structural Health Monitoring of Fiber Composite Materials

This work evaluates and investigates the wireless generation and detection of Lamb-waves on fiber-reinforced materials using surface applied or embedded piezo elements. The general target is to achieve wireless systems or sensor networks for Structural Health Monitoring (SHM), a type of Non-Destructive-Evaluation (NDE). In this sense, a fully wireless measurement system that achieves power transmission implementing inductive coils is reported. This system allows a reduction of total system weight as well as better integration in the structure. A great concern is the characteristics of the material, in which the system is integrated, because the properties can have a direct impact on the strength of the magnetic field. Carbon-Fiber-Reinforced-Polymer (CFRP) is known to behave as an electrical conductor, shielding radio waves with increasing worse effects at higher frequencies. Due to the need of high power and voltage, interest is raised to evaluate the operation of piezo as actuators at the lower frequency ranges. To this end, actuating occurs at the International Scientific and Medical (ISM) band of 125 kHz or low-frequency (LF) range. The feasibility of such system is evaluated extensively in this work. Direct excitation, is done by combining the actuator bonded to the surface or embedded in the material with an inductive LF coil and setting the circuit in resonance. A more controlled possibility, also explored, is the use of electronics to generate a Hanning-windowed-sine to excite the PWAS in a narrow spectrum. In this case, only wireless power is transmitted to the actuator node, and this lastly implements a Piezo-driver to independently excite Lamb-waves. Sensing and data transfer, on the other hand, is done using the high-frequency (HF) 13.56 MHz. The HF range covers the requirements of faster sampling rate and lower energy content. A re-tuning of the antenna coils is performed to obtain better transmission qualities when the system is implemented in CFRP. Several quasi-isotropic (QI) CFRP plates with sensor and actuator nodes were made to measure the quality of transmission and the necessary energy to stimulate the actuator-sensor system. In order to produce baselines, measurements are prepared from a healthy plate under specific temperature and humidity conditions. The signals are evaluated to verify the functionality in the presence of defects. The measurements demonstrate that it is possible to wirelessly generate Lamb-waves while early results show the feasibility to determine the presence of structural failure. For instance, progress has been achieved detecting the presence of a failure in the form of drilled holes introduced to the structure. This work shows a complete set of experimental results of different sensor/-actuator nodes

Oxide Nanoelectronics

This thesis describes research performed on two types of complex oxide heterostructures. The first consists of ultrathin LaAlO3 films grown on SrTiO3 substrates. At the interface between these two insulating oxides, a quasi two dimensional electron gas may form under proper conditions. This interface has remarkable properties such as interfacial superconductivity, interfacial magnetism and a hysteretic voltage-controlled metal-insulator transition. We developed an Atomic Force Microscope (AFM) lithography technique which is capable of switching reversibly at room temperature this metal-insulator transition with nanometer scale spatial resolution. Based on this technique, conducting nanowires as thin as 2 nm and nanodots array with density up to 1014 inch-2 were written, probed and erased. Sketch-defined field effect transistors (SketchFET) with channel lengths as short as 2 nm were fabricated. These structures were characterized over a temperature range 15 K-300 K, revealing a complex energy landscape. Magnetotransport measurements performed at temperatures at and below 1 K reveal a variety of intriguing quantum phenomena, including integer and fractional quantum Hall states. The second material system consists of thin films of SrTiO3 grown directly on silicon. Although SrTiO3 is not ferroelectric at any temperature in bulk form, when strained to the silicon lattice it can become ferroelectric at and above room temperature. Temperature-dependent piezo force microscopy was performed to verify that those strain engineered films with certain thickness are indeed ferroelectric. Ultrafast optical experiments were carried out to measure lattice dynamics in these strained films. A coherent acoustic phonon mode was observed and studied as a function of film thickness and laser polarization. Using SrTiO3 grown on silicon-on-insulator structures, ferroelectric field effect transistors (FeFET) were fabricated and characterized at room temperature

Current measurement in power electronic and motor drive applications - a comprehensive study

Current measurement has many applications in power electronics and motor drives. Current measurement is used for control, protection, monitoring, and power management purposes. Parameters such as low cost, accuracy, high current measurement, isolation needs, broad frequency bandwidth, linearity and stability with temperature variations, high immunity to dv/dt, low realization effort, fast response time, and compatibility with integration process are required to ensure high performance of current sensors. Various current sensing techniques based on different physical effects such as Faraday\u27s induction law, Ohm\u27s law, Lorentz force law, magneto-resistance effect, and magnetic saturation are studied in this thesis. Review and examination of these current measurement methods are presented. The most common current sensing method is to insert a sensing resistor in the path of an unknown current. This method incurs significant power loss in a sense resistor at high output currents. Alternatives for accurate and lossless current measurement are presented in this thesis. Various current sensing techniques with self-tuning and self-calibration for accurate and continuous current measurement are also discussed. Isolation and large bandwidth from dc to several kilo-hertz or mega-hertz are the most difficult, but also most crucial characteristics of current measurement. Electromagnetic-based current sensing techniques, which are used to achieve these characteristics, are analyzed. Many applications require average current information for control purposes. Different average current sensing methods of measuring average current are also reviewed. --Abstract, page iii

Label-free detection of biomolecules with Ta2O5-based field effect devices

Dissertação para obtenção do Grau de Doutor em Nanotecnologias e NanociênciasInternational Iberian Nanotechnology Laboratory (INL

Three dimensional magnetic field sensors and array in BiCMOS technology

This thesis presents new designs of three dimensional magnetic field sensors in BiCMOS technology. The detailed design of the merged structure device by common diffusion and the high gain transduction circuit are presented. The merged structure has the advantage of less area, less external contacts and less parasitic capacitance. Cross-sensitivity is also eliminated by employing the merged structure. Three active on-chip loads are introduced to improve the sensitivity. The SPICE simulation results show that when a relative change in current ΔI/I is 0.001, about 13.6 mV and 8.5mV can be detected at the output in X(or Y) and Z directions, respectively. The experimental results from a standard (non-merged) BiCMOS magnetic sensor is presented. The 3-D sensor element has been integrated with the signal processing circuits to build a monolithic 8 x 8 sensor array. The detailed SPICE simulation results on the critical path shows the array can be operated with elimination of column-to-column offset voltages under a maximum scanning clock speed of about 0.5MHz. The array structure can find application in precise manufacturing as a position sensor

Carbon Nanotube Interconnect Modeling for Very Large Scale Integrated Circuits

In this research, we have studied and analyzed the physical and electrical properties of carbon nanotubes. Based on the reported models for current transport behavior in non-ballistic CNT-FETs, we have built a dynamic model for non-ballistic CNT-FETs. We have also extended the surface potential model of a non-ballistic CNT-FET to a ballistic CNT-FET and developed a current transport model for ballistic CNT-FETs. We have studied the current transport in metallic carbon nanotubes. By considering the electron-electron interactions, we have modified two-dimensional fluid model for electron transport to build a semi-classical one-dimensional fluid model to describe the electron transport in carbon nanotubes, which is regarded as one-dimensional system. Besides its accuracy compared with two-dimensional fluid model and Lüttinger liquid theory, one-dimensional fluid model is simple in mathematical modeling and easier to extend for electronic transport modeling of multi-walled carbon nanotubes and single-walled carbon nanotube bundles as interconnections. Based on our reported one-dimensional fluid model, we have calculated the parameters of the transmission line model for the interconnection wires made of single-walled carbon nanotube, multi-walled carbon nanotube and single-walled carbon nanotube bundle. The parameters calculated from these models show close agreements with experiments and other proposed models. We have also implemented these models to study carbon nanotube for on-chip wire inductors and it application in design of LC voltage-controlled oscillators. By using these CNT-FET models and CNT interconnects models, we have studied the behavior of CNT based integrated circuits, such as the inverter, ring oscillator, energy recovery logic; and faults in CNT based circuits

Design of an electric drivetrain for the Formula Student-class vehicle

Hlavním úkolem této diplomové práce bylo navrhnout a postavit funkční prototyp frekvenčního měniče pro použití ve vozidlech týmu eForce FEE Prague Formula, soutěžícího v mezinárodní inženýrské soutěži Formula Student. Práce je členěna do několika kapitol, kdy je nejdříve prozkoumán již minule provedený vývoj v týmu. Dále je vystavěna potřebná teorie pro vývoj frekvenčního měniče. Další kapitola detailně popisuje provedený vývoj zařízení. Poslední kapitoly se věnují zhodnocení navrženého měniče. Diplomová práce také prozkoumala nové možnosti v měření fázových proudů, umožňující vysokou přesnost při zachování nízké ceny a kompaktních rozměrů. Celkovým cílem bylo navrhnout jednoduché a robustní zařízení s nízkou výrobní cenou. Ověřování návrhu bylo provedeno v laboratořích fakulty pro ujištění připravenosti navrženého měniče pro nasazení do vozidla. Práce bude pokračovat na vylepšování řídícího algoritmu a postupné integraci do týmových vozidel.This thesis' main objective was to design and develop a functional motor controller for usage in a Formula Student competition vehicle of the eForce FEE Prague Formula team. Work is split into several chapters. Exploring a drivetrain development progression in the team, presenting a needed theory for a motor controller development and giving a detailed overview of the designed device. The last chapters are dedicated to evaluation of the design. Thesis had explored a new methodology in a phase current sensing, providing a significant precision while allowing for a low cost and compact design. Overall aim was to create a simple, robust and cheap solution. Verification of the design was performed in the laboratory environment of the faculty in order to ensure preparedness for integration into the vehicle. Further work will focus on control strategy improvements and final integration into the team's vehicles

MOSFET transistor fabrication on AFM tip

The project is concerned with the development of methods for the fabrication of magnetic sensor devices on Atomic Force Microscopy (AFM) probes and their characterization. The devices use the principle of the Hall effect (based on the Lorentz force) to sense the magnetic properties of a magnetized specimen. In the past Hall bar sensors have been fabricated using semimetals such as Bismuth, or using 2-d electron gas material based on heterojunctions in III-V material. The former probes are limited by low sensitivity. The latter are limited by the difficulty encountered when trying to integrate the device with a force-sensing cantilever. The highest spatial resolution reported for a Hall bar operating at room temperature is 50 nm. Due to quantum effects (long mean free path), scaling down devices based on high mobility material results in a drop in sensitivity. For magnetic material studies of current interest higher resolutions are required. To achieve this goal in a material system which is compatible with micromachining the proposed approach utilises silicon as the sensing material. Silicon Hall bars have already been reported to work for large scale devices. This thesis presents the development of p-type enhancement mode MOSFET transistor fabrication process on a tip of Atomic Force Microscope (AFM) probe. The active device fabrication process was developed in order to allow fabrication of a magnetic sensor for Scanning Hall Probe Microscope (SHPM). The Hall bar was constructed on the apex of the AFM tip of attractive mode probes. The fabrication is performed in batches by using common semiconductor techniques leading to micromachining of the Si substrate, formation of the active device and cantilever release step. The transistor characteristics are presented, compared with expected performance of the modelled device and the reasons for differences are discussed. In this work, a method for application of spin-on-dopant on highly topographic structures is developed. Other encountered process incompatibilities are dealt with to finally present a full process for p-type enhancement mode MOSFET transistor on AFM tip fabrication