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Book Passivation of Amorphous Indium gallium zinc Oxide IGZO Thin film Transistors

Download or read book Passivation of Amorphous Indium gallium zinc Oxide IGZO Thin film Transistors written by Nathaniel Walsh and published by . This book was released on 2014 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Thin-film transistors (TFTs) with channel materials made out of hydrogenated amorphous silicon (a-Si:H) and polycrystalline silicon (poly-Si) have been extensively investigated. Amorphous silicon continues to dominate the large-format display technology; however newer technologies demand a higher performance TFT which a-Si:H cannot deliver due to its low electron mobility, μn ~ 1 cm2/V*s. Metal-oxide materials such as Indium-Gallium-Zinc Oxide (IGZO) have demonstrated semiconductor properties, and are candidates to replace a Si:H for TFT backplane technologies. This work involves the fabrication and characterization of TFTs utilizing a-IGZO deposited by RF sputtering. An overview of the process details and results from recently fabricated IGZO TFTs following designed experiments are presented, followed by analysis of electrical results. The investigated process variables were the thickness of the IGZO channel material, passivation layer material, and annealing conditions. The use of electron-beam deposited Aluminum oxide (alumina or Al2O3) as back-channel passivation material resulted in improved device stability; however ID VG transfer characteristics revealed the influence of back-channel interface traps. Results indicate that an interaction effect between the annealing condition (time/temperature) and the IGZO thickness on the electrical behavior of alumina-passivated devices may be significant. A device model implementing fixed charge and donor-like interface traps that are consistent with oxygen vacancies (OV) resulted in a reasonable match to measured characteristics. Modified annealing conditions have resulted in a reduction of back-channel interface traps, with levels comparable to devices fabricated without the addition of passivation material."--Abstract.

Book Transparent Oxide Electronics

Download or read book Transparent Oxide Electronics written by Pedro Barquinha and published by John Wiley & Sons. This book was released on 2012-03-15 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transparent electronics is emerging as one of the most promising technologies for the next generation of electronic products, away from the traditional silicon technology. It is essential for touch display panels, solar cells, LEDs and antistatic coatings. The book describes the concept of transparent electronics, passive and active oxide semiconductors, multicomponent dielectrics and their importance for a new era of novel electronic materials and products. This is followed by a short history of transistors, and how oxides have revolutionized this field. It concludes with a glance at low-cost, disposable and lightweight devices for the next generation of ergonomic and functional discrete devices. Chapters cover: Properties and applications of n-type oxide semiconductors P-type conductors and semiconductors, including copper oxide and tin monoxide Low-temperature processed dielectrics n and p-type thin film transistors (TFTs) – structure, physics and brief history Paper electronics – Paper transistors, paper memories and paper batteries Applications of oxide TFTs – transparent circuits, active matrices for displays and biosensors Written by a team of renowned world experts, Transparent Oxide Electronics: From Materials to Devices gives an overview of the world of transparent electronics, and showcases groundbreaking work on paper transistors

Book Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Non volatile Memory and Circuits for Transparent Electronics

Download or read book Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Non volatile Memory and Circuits for Transparent Electronics written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to make electronic devices, that are transparent to visible and near infrared wavelength, is a relatively new field of research in the development of the next generation of optoelectronic devices. A new class of inorganic thin-film transistor (TFT) channel material based on amorphous oxide semiconductors, that show high carrier mobility and high visual transparency, is being researched actively. The purpose of this dissertation is to develop amorphous oxide semiconductors by pulsed laser deposition, show their suitability for TFT applications and demonstrate other classes of devices such as non-volatile memory elements and integrated circuits such as ring oscillators and active matrix pixel elements. Indium gallium zinc oxide (IGZO) is discussed extensively in this dissertation. The influence of several deposition parameters is explored and oxygen partial pressure during deposition is found to have a profound effect on the electrical and optical characteristics of the IGZO films. By optimizing the deposition conditions, IGZO TFTs exhibit excellent electrical properties, even without any intentional annealing. This attribute along with the amorphous nature of the material also makes IGZO TFTs compatible with flexible substrates opening up various applications. IGZO TFTs with saturation field effect mobility of 12 â€" 16 cm2 V-1 s-1 and subthreshold voltage swing of 200 mV decade-1 have been fabricated. By varying the oxygen partial pressure during deposition the conductivity of the channel was controlled to give a low off-state current ~ 10 pA and a drain current on/off ratio of 1 x108. Additionally, the effects of the oxygen partial pressure and the thickness of the semiconductor layer, the choice of the gate dielectric material and the device channel length on the electrical characteristics of the TFTs are explored. To evaluate IGZO TFT electrical stability, constant voltage bias stress measurements were carried out. The observed logarithmic depende.

Book Investigation of Ultra thin In Ga Zn O Thin film Transistors

Download or read book Investigation of Ultra thin In Ga Zn O Thin film Transistors written by Tsung-Han Chiang and published by . This book was released on 2015 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the work reported herein is to explore the impact of decreasing channel thickness on radio-frequency (RF) sputtered amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) electrical performance through the evaluation of drain current versus gate voltage (I[subscript D] - V[subscript G]) transfer curves. For a fixed set of process parameters, it is found that the turn-on voltage, V[subscript ON] (off drain current, I[superscript OFF][subscript D]) increases (decreases) with decreasing a-IGZO channel thickness (h) for h

Book On the Reversible Effects of Bias stress Applied to Amorphous Indium gallium zinc oxide Thin Film Transistors

Download or read book On the Reversible Effects of Bias stress Applied to Amorphous Indium gallium zinc oxide Thin Film Transistors written by Anish Suresh Bharadwaj and published by . This book was released on 2018 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The role of amorphous IGZO (Indium Gallium Zinc Oxide) in Thin Film Transistors (TFT) has found its application in emerging display technologies such as active matrix liquid crystal display (LCD) and active matrix organic light-emitting diode (AMOLED) due to factors such as high mobility 10-20 cm2/(V.s), low subthreshold swing (~120mV/dec), overall material stability and ease of fabrication. However, prolonged application of gate bias on the TFT results in deterioration of I-V characteristics such as sub-threshold distortion and a distinct shift in threshold voltage. Both positive-bias and negative-bias affects have been investigated. In most cases positive-stress was found to have negligible influence on device characteristics, however a stress induced trap state was evident in certain cases. Negative stress demonstrated a pronounced influence by donor like interface traps, with significant transfer characteristics shift that was reversible over a period of time at room temperature. It was also found that the reversible mechanism to pre-stress conditions was accelerated when samples were subjected to cryogenic temperature (77 K). To improve device performance BG devices were subjected to extended anneals and encapsulated with ALD alumina. These devices were found to have excellent resistance to bias stress. Double gate devices that were subjected to extended anneals and alumina capping revealed similar results with better electrostatics compared to BG devices. The cause and effect of bias stress and its reversible mechanisms on IGZO TFTs has been studied and explained with supporting models."--Abstract.

Book Composition Engineering for Solution Processed Gallium Rich Indium Gallium Zinc Oxide Thin Film Transistors

Download or read book Composition Engineering for Solution Processed Gallium Rich Indium Gallium Zinc Oxide Thin Film Transistors written by Isaac Caleb Wang and published by . This book was released on 2018 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal oxides have risen to prominence in recent years as a promising active layer for thin film transistors (TFTs). One of the main reasons for this has been its value in display technology. Conventionally, displays have relied on amorphous hydrogenated silicon (a-Si:H) TFTs but the demand for large area displays with high resolution, fast response time, low power consumption and compatibility with integrated driving circuits have prompted research into other semiconducting materials. As a result, metal oxides have become major prospects to replace a-Si:H with their high-performance electrical characteristics and simplicity of processing, making them valuable switching elements in display technology. Particularly, quaternary metal oxides such as the amorphous Indium-Gallium-Zinc-Oxide (IGZO) have demonstrated extremely high performances as TFTs, prompting extensive research in the field. The conventional method of producing metal oxide thin films has been through vacuum deposition methods such as sputtering. However, for large area applications these vacuum deposition methods face inherent limitations which prevent easy application and device fabrication. Facing these restrictions, solution-processing has become a popularly researched alternative in producing metal oxide thin films due to their simple processing requirements, low cost, and ability to be applied over large areas. In solution-processed IGZO, there have been a couple approaches to improve device performance and stability as well as simplify processing. In this work, we produce a gallium-rich 2:2:1 IGZO TFT using solution processes and study its electrical characteristics and stability. In this paper, we demonstrate a working solution-processed gallium-rich 2:2:1 IGZO TFT and compare it to a solution-processed indium-rich device to quantify its stability and performance. Through this work, we show that solution-processing is a viable fabrication method for gallium-rich IGZO, which can be a high-stability alternative to other compositions of IGZO devices.

Book Post Processing Treatment of InGaZnO Thin Film Transistors for Improved Bias illumination Stress Reliability

Download or read book Post Processing Treatment of InGaZnO Thin Film Transistors for Improved Bias illumination Stress Reliability written by Muhammad Ruhul Hasin and published by . This book was released on 2013 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis work mainly examined the stability and reliability issues of amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors under bias-illumination stress. Amorphous hydrogenated silicon has been the dominating material used in thin film transistors as a channel layer. However with the advent of modern high performance display technologies, it is required to have devices with better current carrying capability and better reproducibility. This brings the idea of new material for channel layer of these devices. Researchers have tried poly silicon materials, organic materials and amorphous mixed oxide materials as a replacement to conventional amorphous silicon layer. Due to its low price and easy manufacturing process, amorphous mixed oxide thin film transistors have become a viable option to replace the conventional ones in order to achieve high performance display circuits. But with new materials emerging, comes the challenge of reliability and stability issues associated with it. Performance measurement under bias stress and bias-illumination stress have been reported previously. This work proposes novel post processing low temperature long time annealing in optimum ambient in order to annihilate or reduce the defects and vacancies associated with amorphous material which lead to the instability or even the failure of the devices. Thin film transistors of a-IGZO has been tested for standalone illumination stress and bias-illumination stress before and after annealing. HP 4155B semiconductor parameter analyzer has been used to stress the devices and measure the output characteristics and transfer characteristics of the devices. Extra attention has been given about the effect of forming gas annealing on a-IGZO thin film. a-IGZO thin film deposited on silicon substrate has been tested for resistivity, mobility and carrier concentration before and after annealing in various ambient. Elastic Recoil Detection has been performed on the films to measure the amount of hydrogen atoms present in the film. Moreover, the circuit parameters of the thin film transistors has been extracted to verify the physical phenomenon responsible for the instability and failure of the devices. Parameters like channel resistance, carrier mobility, power factor has been extracted and variation of these parameters has been observed before and after the stress.

Book Amorphous Indium Gallium Zinc Oxide Based Thin Film Transistors and Circuits

Download or read book Amorphous Indium Gallium Zinc Oxide Based Thin Film Transistors and Circuits written by Haojun Luo and published by . This book was released on 2013 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Zinc Oxide Thin Film Transistors for 3D Microelectronic Applications

Download or read book Zinc Oxide Thin Film Transistors for 3D Microelectronic Applications written by Sang Ha Yoo and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the current semiconductor industry trend deviates from Moore's Law due to quantum limits discovered upon further scaling of technology nodes, efforts are being put into three-dimensional (3D) stacking of semiconductor devices in integrated circuits (ICs). Since its conduction band pathway arises from its spherically shaped s-orbital, zinc oxide (ZnO) is a promising material for technological advancement towards 3D-stacked devices since it can theoretically retain its bulk mobility even if it is processed at a low temperature. Plasma-enhanced atomic layer deposition (PEALD) system using weak oxidants was utilized to deposit ZnO at a low temperature ( 200 °C), and ZnO thin-film transistors (TFTs) were fabricated based on this system for this study. This dissertation presents efforts to develop ZnO TFTs that are suitable for 3D electronics applications, focusing on high mobility, high current, and scalability aspects of the device. The relationship between the ZnO TFT mobility and the morphology of PEALD ZnO films is studied with emphasis on the grain size variation of the ZnO films. For the nanocrystalline PEALD ZnO films, no direct relationship between grain size and mobility was discovered from the study. On the other hand, a simple N2O-based PEALD Al2O3 passivation layer that enhances the performance of ZnO TFTs by an order of magnitude is developed. The passivated ZnO TFTs exhibit field-effect mobility 90 cm2/Vs and drive current >450 mA/mm. Multiple mobility extraction methods confirm that the high mobility value calculated for the passivated TFTs is not from measurement artifacts. The high current and mobility of the N2O PEALD passivated ZnO TFTs remain even when the passivation layer is selectively removed. The cause of the mobility boost is postulated to be hydrogen incorporation during the passivation process. The high performance of these devices is of interest for 3D ICs and other applications. Metals of different reactivity and work function are explored to overcome the Schottky barrier present in ZnO TFTs. Oxygen vacancies and zinc interstitials generated from the reaction between contact metal and ZnO semiconductors are believed to serve as the source of increased charge carriers to mimic a doping effect at TFT contacts. In addition, doped contact ZnO TFTs are demonstrated as well. We use PEALD ZnO films as the active layer and ALD ZnO films as the doped layer. The fabrication process of PEALD ZnO TFTs with ALD ZnO doped layer resembles that of back-channel-etched a-Si: H TFTs. An acetic acid-based ZnO etchant is used to controllably back etch the channel layer at a rate of 2 nm/sec to etch away the conductive ALD ZnO layer. The fabricated devices exhibit less dominance by the Schottky barrier at contacts. Ferroelectric field-effect transistors (FeFET) using low-temperature processed boron-doped aluminum nitride (Al1-xBxN; AlBN for simplicity) as the gate dielectric are also developed to serve as memory devices combined with ZnO TFT logic devices. With the help of a stable PEALD Al2O3 layer to prevent gate leakage, fabricated ZnO-AlBN FeFETs demonstrated counter-clockwise hysteresis, which is one of the indications of ferroelectricity present in the device. Double-gated ZnO-AlBN FeFETs are also fabricated to further establish that the devices exhibit polarization behavior with known field line terminations. ZnO TFTs and AlBN FeFETs are of interest to the future 3D microelectronics and ICs.

Book Development of Indium Gallium Zinc Oxide Thin Film Transistors on a Softening Shape Memory Polymer for Implantable Neural Interfaces Devices

Download or read book Development of Indium Gallium Zinc Oxide Thin Film Transistors on a Softening Shape Memory Polymer for Implantable Neural Interfaces Devices written by Ovidio Rodriguez Lopez and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The continuous improvement in electronic active devices has led to several innovations in semiconductor materials, novel deposition methods, and improved microfabrication techniques. In the same way, the implementation of thin-film technology has revolutionized the semiconductor industry. For instance, the field of flexible electronics has utilized novel thin-film electronics components for the fabrication flexible displays, radio frequency identification (RF-ID) tags, and solar cells. Moreover, flexible electronics have sparked a great interest in the field of bioelectronics, for the fabrication of high-spatial-resolution implantable devices for neural interfaces. This incorporation of thin-film technology can potentially enable stimulation and recording the nervous system activity by utilizing novel, minimally invasive, conformal devices. To achieve this, flexible electronics circuits must possess high performance, reliability, and stability, as well as be resilient to mechanical stress and human body conditions, are some of the requirements that flexible electronics must meet for the realization of these devices. Furthermore, the choice of substrates is also critical since it directly affects final properties of the active devices. Substrates, which are mechanically and biologically compliant, are preferred. For this reason, novel, softening materials like thiol-ene polymers are considered in this research. This work centers on the development of Indium-Gallium-Zinc-Oxide (IGZO) thin-film transistors (TFT) using the thiol-ene softening polymer as substrate. Functional IGZO-TFTs were fabricated on top of 50 μm of a thiol-ene/acrylate shape memory polymer (SMP) and electrically characterized. Hafnium oxide (HfO2) deposited at 100°C by atomic layer deposition was used as gate dielectric, and gold (Au) as contacts. The devices were exposed to oxygen, vacuum and forming gas (FG) environments at 250°C to analyze the effects of these atmospheres on the IGZO-TFTs. Improvement in the electrical performance was noticed after the exposure to FG with a significant change in mobility from 0.01 to 30 cm2 V-1s-1, and a reduction in the threshold voltage shift (∆Vth), which it is translated into an increase on stability. Vacuum and oxygen effects were, also analyzed and compared. Furthermore, a time-dependent dielectric breakdown (TDDB) analysis was performed to define the lifetime of the transistors, where a prediction of 10 years at an operational range below 5 V was obtained. Additionally, the TFTs were encapsulated with 5 μm of SMP and exposed to simulated in vivo conditions. Up to 104 bending cycles were performed to the IGZO-TFTs with a bending radius of 5 mm and then, soaked into PBS solution at 37°C for one week to determine the resilience and reliability of the devices. The encapsulated IGZO-TFTs survived to the PBS environment and demonstrated resilience to mechanical deformation with small changes in the electronic properties. The results provided in this research contribute to the development of complex circuitry based on thin-film devices using mechanically adaptive polymers as a flexible substrate and enable the production of multichannel implantable bioelectronics devices.