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Book Investigation of Indium Zinc Oxide Thin Film Transistors Fabricated by Sputtered System and Their Optoelectronic Application

Download or read book Investigation of Indium Zinc Oxide Thin Film Transistors Fabricated by Sputtered System and Their Optoelectronic Application written by 溫承樺 and published by . This book was released on 2014 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Investigation of Indium Titanium Zinc Oxide Thin Film Transistors Fabricated by RF Sputtering System and Their Optoelectronic Application

Download or read book Investigation of Indium Titanium Zinc Oxide Thin Film Transistors Fabricated by RF Sputtering System and Their Optoelectronic Application written by 吳韋廷 and published by . This book was released on 2017 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Thin film Transistors Fabricated Using Sputter Deposition of ZnO

Download or read book Thin film Transistors Fabricated Using Sputter Deposition of ZnO written by Nan Xiao and published by . This book was released on 2013 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Development of thin film transistors (TFTs) with conventional channel layer materials, such as amorphous silicon (a-Si) and polysilicon (poly-Si), has been extensively investigated. A-Si TFT currently serves the large flat panel industry; however advanced display products are demanding better TFT performance because of the associated low electron mobility of a-Si. This has motivated interest in semiconducting metal oxides, such as Zinc Oxide (ZnO), for TFT backplanes. This work involves the fabrication and characterization of TFTs using ZnO deposited by sputtering. An overview of the process details and results from recently fabricated TFTs following a full-factorial designed experiment will be presented. Material characterization and analysis of electrical results will be described. The investigated process variables were the gate dielectric and ZnO sputtering process parameters including power density and oxygen partial pressure. Electrical results showed clear differences in treatment combinations, with certain I-V characteristics demonstrating superior performance to preliminary work. A study of device stability will also be discussed."--Abstract.

Book Investigation of Magnesium Indium Oxide Thin Film Fabricated by RF Sputtering System and Their Optoelectronics Applications

Download or read book Investigation of Magnesium Indium Oxide Thin Film Fabricated by RF Sputtering System and Their Optoelectronics Applications written by 陳維德 and published by . This book was released on 2020 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book An Investigation of the Performance and Stability of Zinc Oxide Thin film Transistors and the Role of High k Dielectrics

Download or read book An Investigation of the Performance and Stability of Zinc Oxide Thin film Transistors and the Role of High k Dielectrics written by Ngwashi Divine Khan and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transparent oxide semiconducting films have continued to receive considerable attention, from a fundamental and application-based point of view, primarily because of their useful fundamental properties. Of particular interest is zinc oxide (ZnO), an n-type semiconductor that exhibits excellent optical, electrical, catalytic and gas-sensing properties, and has many applications in various fields. In this work, thin film transistor (TFT) arrays based on ZnO have been prepared by reactive radio frequency (RF) magnetron sputtering. Prior to the TFT fabrication, ZnO layers were sputtered on to glass and silicon substrates, and the deposition parameters optimised for electrical resistivities suitable for TFT applications. The sputtering process was carried out at room temperature with no intentional heating. The aim of this work is to prepare ZnO thin films with stable semiconducting electrical properties to be used as the active channel in TFTs; and to understand the role of intrinsic point defects in device performance and stability. The effect of oxygen (O2) adsorption on TFT device characteristics is also investigated. The structural quality of the material (defect type and concentration), electrical and optical properties (transmission/absorption) of semiconductor materials are usually closely correlated. Using the Vienna ab-initio simulation package (VASP), it is predicted that O2 adsorption may influence film transport properties only within a few atomic layers beneath the adsorption site. These findings were exploited to deposit thin films that are relatively stable in atmospheric ambient with improved TFT applications. TFTs incorporating the optimised layer were fabricated and demonstrated very impressive performance metrics, with effective channel mobilities as high as 30 cm2/V-1s-1, on-off current ratios of 107 and sub-threshold slopes of 0.9? 3.2 V/dec. These were found to be dependent on film thickness (~15? 60 nm) and the underlying dielectric (silicon dioxide (SiO2), gadolinium oxide (Gd2O3), yttrium oxide (Y2O3) and hafnium oxide (HfO2)). In this work, prior to sputtering the ZnO layer (using a ZnO target of 99.999 % purity), the sputtering chamber was evacuated to a base pressure ~4 x 10-6 Torr. Oxygen (O2) and argon (Ar) gas (with O2/Ar ratio of varying proportions) were then pumped into the chamber and the deposition process optimised by varying the RF power between 25 and 500 W and the O2/Ar ratio between 0.010 to 0.375. A two-level factorial design technique was implemented to test specific parameter combinations (i.e. RF power and O2/Ar ratio) and then statistical analysis was utilised to map out the responses. The ZnO films were sputtered on glass and silicon substrates for transparency and resistivity measurements, and TFT fabrication respectively. For TFT device fabrication, ZnO films were deposited onto thermally-grown silicon dioxide (SiO2) or a high-k dielectric layer (HfO2, Gd2O3 and Y2O3) deposited by a metal-organic chemical deposition (MOCVD) process. Also, by using ab initio simulation as implemented in the?Vienna ab initio simulation package (VASP)?, the role of oxygen adsorption on the electrical stability of ZnO thin film is also investigated. The results indicate that O2 adsorption on ZnO layers could modify both the electronic density of states in the vicinity of the Fermi level and the band gap of the film. This study is complemented by studying the effects of low temperature annealing in air on the properties of ZnO films. It is speculated that O2 adsorption/desorption at low temperatures (150? 350 0C) induces variations in the electrical resistance, band gap and Urbach energy of the film, consistent with the trends predicted from DFT results.

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 Zinc Oxide Thin Film Transistors

    Book Details:
  • Author : Divine Khan Ngwashi
  • Publisher : LAP Lambert Academic Publishing
  • Release : 2011-05
  • ISBN : 9783844396539
  • Pages : 160 pages

Download or read book Zinc Oxide Thin Film Transistors written by Divine Khan Ngwashi and published by LAP Lambert Academic Publishing. This book was released on 2011-05 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transparent oxide semiconducting films have continued to receive considerable attention, from a fundamental and application-based point of view, primarily because of their useful fundamental properties. Of particular interest is zinc oxide (ZnO), an n-type semiconductor that exhibits excellent optical, electrical, catalytic and gas-sensing properties, and has many applications in various fields. In this work, thin film transistor (TFT) arrays based on ZnO have been prepared by reactive radio frequency (RF) magnetron sputtering. The sputtering process was carried out at room temperature with no intentional heating. The aim of this is to prepare ZnO thin films with stable semiconducting electrical properties to be used as the active channel in TFTs; and to understand the role of intrinsic point defects in device performance and stability. The effect of oxygen (O2) adsorption on TFT device characteristics is also investigated. TFTs incorporating silicon dioxide, and different high-k dielectrics are also investigated.

Book Investigation of Optical and Electrical Properties of Gallium Zinc Tin Oxide  GaZTO  Thin Film Transistors by RF Sputter and Its Optoelectronic Application

Download or read book Investigation of Optical and Electrical Properties of Gallium Zinc Tin Oxide GaZTO Thin Film Transistors by RF Sputter and Its Optoelectronic Application written by 許至淳 and published by . This book was released on 2018 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Thin Film Electronics with Novel Materials

Download or read book Thin Film Electronics with Novel Materials written by Yiyang Gong and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Novel materials, including zinc oxide (ZnO) and 2D transition metal dichalcogenides (TMDs), have been investigated in this dissertation for the realization of high-performance large-area integrated circuits. These novel materials may provide differential advantages over the established large-area thin film technology based on silicon, which has been extensively employed in applications such as large-area flat panel displays, high-speed active matrix thin film circuits, flexible and wearable electronics, etc. The dissertation begins with the discussion of high-performance plasma-enhanced atomic layer deposition (PEALD) of ZnO thin films and ZnO thin film transistors (TFTs) with a field effect mobility of ~ 10 to 20 cm2/Vs, which have been demonstrated. Offset-drain ZnO TFTs, which are able to withstand or switch voltage beyond 80 V, have also been demonstrated. These results shed light on the realization of large-area active-matrix circuits beyond the capabilities of the current display industry where high circuit speed or high operation voltage is required. To further improve the performance of ZnO-based electronics, many related materials, including doped ZnO, zinc nitride, and aluminum nitride, have been investigated. Doped ZnO has been proposed as the carrier injection layer that can improve the conductivity of metal-semiconductor contact in ZnO TFTs. Aluminum-doped ZnO thin films have been deposited using triisobutyl aluminum (TIBA) as the dopant precursor instead of trimethyl aluminum (TMA) in order to improve the uniformity of dopant distribution because TIBA has much lower vapor pressure than TMA. AZO thin films with resistivity ~ 10-2 cm have been achieved by PEALD. Besides, aluminum nitride and zinc nitride thin films have also been studied using PEALD. In addition to the showerhead PEALD system, a novel inductively coupled plasma ALD system has been designed and set up that provides RF power up to 500 W in order to generate a highly reactive nitrogen plasma source and enable the deposition of high-quality metal nitride at relatively low temperature. These metal nitride thin films may provide additional building blocks to enhance the speed and thermal stability of ZnO-based thin film devices and circuits.Owing to their excellent electrical and mechanical properties, 2D-TMD thin films have been studied for flexible electronics applications. High quality MoS2 and WS2 thin films have been achieved via mechanical exfoliation and chemical vapor deposition. To fabricate MoS2- and WS2-based TFTs, a 5-step device fabrication process has been developed, which is compatible to both the conventional rigid substrate and the ~ 4.8 nm thick solution-cast polyimide (PI) flexible substrate. The MoS2 and WS2 TFTs fabricated on PI substrate exhibit a field effect mobility of between 1 to 20 cm2/Vs, which is similar to that of those fabricated on rigid silicon substrate. More importantly, extraordinary mechanical strength and stability have been demonstrated for MoS2 and WS2 TFTs fabricated on PI substrate. A reasonably small degradation in device performance has been observed in these flexible 2D-TMD TFTs under static bending to the radius of ~ 2mm and after cyclic bending up to 100,000 cycles. Finally, attempts to create integratable 2D-TMD circuits have been demonstrated. To realize large-area 2D-TMD based circuits, growth of wafer-scale continuous WSe2 thin films has been demonstrated using metal organic chemical vapor deposition (MOCVD). Deposition has been achieved at as low as 400 C, which allows deposition on glass and polymeric substrate and enables the transfer-free fabrication of WSe2 TFTs and circuits on arbitrary platforms. Patterning and post-growth thickness modulation of continuous WSe2 thin film have been demonstrated using CF4 plasma and O2 plasma, whereby high-speed etching and nanometer-scale film thinning can be realized. With the capability of depositing and patterning wafer-scale WSe2 thin films, an array of p-channel WSe2 TFTs have been fabricated with a field effect mobility of ~0.01 cm2/Vs and an on-off ratio greater than 104.

Book Reactive High Power Impulse Magnetron Sputtering of Zinc Oxide for Thin Film Transistor Applications

Download or read book Reactive High Power Impulse Magnetron Sputtering of Zinc Oxide for Thin Film Transistor Applications written by Amber Nicole Reed and published by . This book was released on 2015 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is an emerging thin film transistor (TFT) material for transparent flexible displays and sensor technologies, where low temperature synthesis of highly crystallographically ordered films over large areas is critically needed. This study maps plasma assisted synthesis characteristics, establishes polycrystalline ZnO growth mechanisms and demonstrates for the first time low-temperature and scalable deposition of semiconducting grade ZnO channels for TFT applications using reactive high power impulse magnetron sputtering (HiPIMS). Plasma parameters, including target currents, ion species and their energies were measured at the substrate surface location with mass spectroscopy as a function of pressure and applied voltage during HiPIMS of Zn and ZnO targets in O2/Ar. The results were correlated to film microstructure development investigated with x-ray diffraction, atomic force microscopy, scanning electron microscopy and transmission electron microscopy which helped establish film nucleation and growth mechanisms. Competition for nucleation by (100), (101) and (002) oriented crystallites was identified at the early stages of film growth, which can result in a layer of mixed crystal orientation at the substrate interface, a microstructural feature that is detrimental to TFT performance due to increased charge carrier scattering in back-gated TFT devices. The study revealed that nucleation of both (100) and (101) orientations can be suppressed by increasing the plasma density while decreasing ion energy. After the initial nucleation layer, the microstructure evolves to strongly textured with the (002) crystal plane oriented parallel to the substrate surface. The degree of (002) alignment was pressure-dependent with lower deposition pressures resulting in films with (002) alignment less than 3.3°, a trend attributed to less energy attenuation of the low energy (2- 6 eV) Ar+, O+, and O2+ ions observed with mass spectrometry measurements. At pressures of 7 mTorr and lower, a second population of ionized gas (Ar+, O+, and O2+) species with energies up to 50 eV appeared. The presence of higher energy ions corresponded with a bimodal distribution of ZnO grain sizes, confirming that high energy bombardment has significant implications on microstructural uniformity during large area growth. Based on the established correlations between process parameters, plasma characteristics, film structure and growth mechanisms, optimum deposition conditions for (002) oriented nanocrystalline ZnO synthesis at 150 °C were identified and demonstrated for both silicon oxide wafers of up to 4 inch diameter and on flexible polymer (Kapton) substrates. The feasibility of the low temperature processing of ZnO films for TFT applications was verified by preliminary tests with back-gated device prototypes. Directions of future research are outlined to further develop this low temperature growth method and apply results of this study for ZnO applications in semiconductor devices.