Author: 蘇鵬宇Publisher:
ISBN:
Category :
Languages : en
Pages : 128
Book Description
Fabrication and Analysis of Indium Gallium Zinc Oxide Transparent Thin Film Transistors
Author: 蘇鵬宇Fabrication of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors by Focused Ion Beam
Author: Wencong ZhuDevelopment of Indium Gallium Zinc Oxide Thin Film Transistors on a Softening Shape Memory Polymer for Implantable Neural Interfaces Devices
Author: Ovidio Rodriguez LopezPublisher:
ISBN:
Category : Brain-computer interfaces
Languages : en
Pages :
Book Description
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.
Indium-Gallium-Zinc Oxide Thin-Film Transistors for Active-Matrix Flat-Panel Displays
Author: Forough MahmoudabadiPublisher:
ISBN: 9781369637359
Category :
Languages : en
Pages : 178
Book Description
In this work, a robust process for fabrication of bottom-gate and top-gate a-IGZO TFTs is presented. An analytical drain current model for a-IGZO TFTs is proposed and its validation is demonstrated through experimental results. The instability mechanisms in a-IGZO TFTs under high current stress is investigated through low-frequency noise measurements. For the first time, the effect of engineered glass surface on the performance and reliability of bottom-gate a-IGZO TFTs is reported.
Fabrication and Characterization of Oxide-based Thin Film Transistors, and Process Development for Oxide Heterostructures
Author: Wantae LimPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
ABSTRACT: This dissertation is focused on the development of thin film transistors (TFTs) using oxide materials composed of post-transitional cations with (n-1)d10ns0 (n[more than or equal to]4). The goal is to achieve high performance oxide-based TFTs fabricated at low processing temperature on either glass or flexible substrates for next generation display applications. In addition, etching mechanism and Ohmic contact formation for oxide heterostructure (ZnO/CuCrO2) system is demonstrated. The deposition and characterization of oxide semiconductors (In2O3-Zn0, and InGaZnO4) using a RF-magnetron sputtering system are studied. The main influence on the resistivity of the films is found to be the oxygen partial pressure in the sputtering ambient. The films remained amorphous and transparent (> 70%) at all process conditions. These films showed good transmittance at suitable conductivity for transistor fabrication. The electrical characteristics of both top- and bottom-gate type Indium Zinc Oxide (InZnO) and Indium Gallium Zinc Oxide (InGaZnO4)-based TFTs are reported. The InZnO films were favorable for depletion-mode TFTs due to their tendency to form oxygen vacancies, while enhancement-mode devices were realized with InGaZnO4 films. The InGaZnO4-based TFTs fabricated on either glass or plastic substrates at low temperature (
Composition Engineering for Solution-Processed Gallium-Rich Indium-Gallium-Zinc-Oxide Thin Film Transistors
Author: Isaac Caleb WangPublisher:
ISBN:
Category :
Languages : en
Pages : 60
Book Description
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.
Passivation of Amorphous Indium-gallium-zinc Oxide (IGZO) Thin-film Transistors
Author: Nathaniel WalshPublisher:
ISBN:
Category : Integrated circuits
Languages : en
Pages : 90
Book Description
"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.
Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors, Non-volatile Memory and Circuits for Transparent Electronics
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
Fabrication and Characterization of Thin-film Transistor Materials and Devices
Author: David HongPublisher:
ISBN:
Category : Thin film transistors
Languages : en
Pages : 266
Book Description
A class of inorganic thin-film transistor (TFT) semiconductor materials has emerged involving oxides composed of post-transitional cations with (n-1)d10ns° (n[greater than or equal to]4) electronic configurations. This thesis is devoted to the pursuit of topics involving the development of these materials for TFT applications: Deposition of zinc oxide and zinc tin oxide semiconductor layers via reactive sputtering from a metal target, and the characterization of indium gallium zinc oxide (IGZO)-based TFTs utilizing various insulator materials as the gate dielectric. The first topic involves the deposition of oxide semiconductor layers via reactive sputtering from a metal target. Two oxide semiconductors are utilized for fabricating TFTs via reactive sputtering from a metal target: zinc oxide and zinc tin oxide. With optimized processing parameters, zinc oxide and zinc tin oxide via this deposition method exhibit similar characteristics to TFTs fabricated via sputtering from a ceramic target. Additionally the effects of gate capacitance density and gate dielectric material are explored utilizing TFTs with IGZO as the semiconductor layers. IGZO-based TFTs exhibit ideal behavior with improved TFT performance such as higher current drive at a given overvoltage, a decrease in the subthreshold swing, and a decrease in the magnitude of the turn-on voltage. Additionally it is shown that silicon dioxide is the preferred dielectric material, with silicon nitride a poor choice for oxide-based TFTs. Finally a simple method to characterize the band tail state distribution near the conduction band minimum of a semiconductor by analyzing two-terminal current-voltage characteristics of a TFT with a floating gate is presented. The characteristics trap energy (E[subscript T]) as a function of post-deposition annealing temperature is shown to correlate very well with IGZO TFT performance, with a lower value of E[subscript T], corresponding to a more abrupt distribution of band tail states, correlating with improved TFT mobility. It is shown that as the post-deposition anneal temperature increases, the total number of band tail states does not change significantly, however the energy distribution of these states approaches that of a crystalline material.
Author: Arun Suresh