High-mobility Thin-film Transistors Research Articles

Biomimetic wafer-scale alignment of tellurium nanowires for high-mobility flexible and stretchable electronics.

Flexible and stretchable thin-film transistors (TFTs) are crucial in skin-like electronics for wearable and implantable applications. Such electronics are usually constrained in performance owing to a lack of high-mobility and stretchable semiconducting channels. Tellurium, a rising semiconductor with superior charge carrier mobilities, has been limited by its intrinsic brittleness and anisotropy. Here, we achieve highly oriented arrays of tellurium nanowires (TeNWs) on various substrates with wafer-scale scalability by a facile lock-and-shear strategy. Such an assembly approach mimics the alignment process of the trailing tentacles of a swimming jellyfish. We further apply these TeNW arrays in high-mobility TFTs and logic gates with improved flexibility and stretchability. More specifically, mobilities over 100 square centimeters per volt per second and on/off ratios of ~104 are achieved in TeNW-TFTs. The TeNW-TFTs on polyethylene terephthalate can sustain an omnidirectional bending strain of 1.3% for more than 1000 cycles. Furthermore, TeNW-TFTs on an elastomeric substrate can withstand a unidirectional strain of 40% with no performance degradation.

High mobility and hysteresis free InGaSnO thin film transistors by co-sputtering via low temperature post annealing process

In this work, InGaSnO thin film transistors (TFTs) with high mobility (>50 cm2/Vs) were prepared by a simple co-sputtering process at a low temperature of 150 ℃. In the co-sputtering process of InSnO and Ga2O3, the composition of InGaSnO can be reasonably controlled by adjusting the sputtering power in the radio frequency plasma, which significantly affects the electrical performance and stability of InGaSnO TFTs. The highly overlapping 5 s electron cloud of In and Sn and the high binding energy of Sn-O lay the foundation for the high mobility of InGaSnO TFTs. The defects related to oxygen in the channel are suppressed by the reasonable control of the composition of Ga in the multicomponent oxides. Meanwhile, the interface defects between the gate dielectric and the active layer are reduced, and a dense metal-oxygen-metal network is formed which is conducive to electron transmission. We have achieved an InGaSnO TFTs with mobility of 58.7 cm2/Vs and threshold voltage of -1.33 V. The stability under positive and negative bias stress is also significantly improved. In general, a simple co-sputtering process is entirely feasible to realize high-mobility oxide TFTs. The control of the process temperature below 150 ℃ also extends its application in flexible electronic devices.

Inkjet printing high mobility indium-zinc-tin oxide thin film transistor

Metal oxide thin film transistor has been widely used in flat panel display industry because of its low leakage current, high mobility and large area uniformity. Besides, with the development of printed display technology, inkjet printing process can fabricate the customizable patterns on diverse substrates with no need of vacuum or lithography to be used, thus significantly reducing cost and receiving more and more attention. In this paper, we use inkjet printing technology to prepare a bottom gate bottom contact thin film transistor (TFT) by using indium-zinc-tin-oxide (IZTO) semiconductor. The surface morphology of the printed IZTO film is modified by adjusting the solvent composition and solute concentration of the printing precursor ink. The experimental result show that the use of binary solvents can effectively overcome the coffee ring shape caused by the accumulation of solute edge in the volatilization process of a single solvent, ultimately presenting a uniform and flat contour surface. Further increase in solute concentration is in favor of formation of convex surface topology. The reason for the formation of the flat surface of the oxide film is the balance between the inward Marangoni reflux of the solute and the outward capillary flow during volatilization. In addition, IZTO thin film transistor printed with binary solvents exhibits excellent electrical properties. The ratio of width/length = 50/30 exhibits a high on-off ratio of 1.21×10<sup>9</sup>, a high saturation field-effect mobility is 16.6 cm<sup>2</sup>/(V·s), a low threshold voltage is 0.84 V, and subthreshold swing is 0.24 V/dec. The uniform and flat active layer thin film pattern can form good contact with the source leakage electrode, and the contact resistances of TFT devices with different width-to-length ratios are less than 1000 Ω, which can reach the basic conditions of high mobility thin film transistors prepared by inkjet printing. Therefore, using solvent mixture provides a universal and simple way to print oxide films with required surface topology, and present a visible path for inkjet printing of high-mobility thin film transistors.

High‐performance, coplanar amorphous InGaZnO thin‐film transistors by spray pyrolysis on polyimide substrate for low‐cost manufacturing of foldable active‐matrix organic light emitting diode display

AbstractWe report a method for low‐cost deposition of bubble‐free, high‐quality amorphous InGaZnO (a‐IGZO) on polyimide (PI) substrate for foldable active‐matrix organic light emitting diode (AMOLED) display by spray pyrolysis. The coplanar thin‐film transistor (TFT) with spray‐pyrolyzed (SP) a‐IGZO on PI substrate exhibits threshold voltage (VTH) of −0.8 V, saturation mobility of 40.95 cm2 V−1 s−1, and subthreshold swing of 0.18 V per decade with on/off drain current ratio of ~108. The high mobility TFT could be achieved using high substrate temperature (350°C) and low contact resistance by NF3 plasma on the SP a‐IGZO. The TFT shows a ΔVTH of −0.4 V when it is bent on a cylinder of 1‐mm radius. The TFT shows the ΔVTH of +0.05 V for positive bias temperature stress at +20 V at 60°C for 1 h. The ring oscillator made of a‐IGZO TFTs exhibits an oscillation frequency of 2.38 MHz at VDD of 10 V with a propagation delay of 9.13 ns per stage. Therefore, the a‐IGZO TFT by spray pyrolysis could be used for low‐cost, high‐performance, and flexible display TFT backplane.

High-performance ITO/a-IGZO heterostructure TFTs enabled by thickness-dependent carrier concentration and band alignment manipulation

Utilization of highly conductive metal-oxide (MO) film such as indium-tin-oxide (ITO) in a channel layer has been considered as a promising strategy to realize high-mobility thin-film transistors (TFTs). However, achieving high-mobility is typically restricted by severe negative threshold voltage (Vth) shift and large off-current which are consequences of channel thickness increment. Here, to realize high-mobility MO TFTs with low Vth and off-current level, a heterogeneous ITO/amorphous indium-gallium-zinc-oxide (a-IGZO) channel structure was implemented. In the channel, the ultrathin (4 nm) ITO layer contributes to retain high electron concentration and boost the mobility, while the overlayered a-IGZO layer mitigates Vth shift and off-current increase. The ITO/a-IGZO TFTs optimized via the thickness-dependent carrier concentration of ITO and band alignment manipulation in the bilayer considerably improved the device performance showing saturation field-effect mobility of >61 cm2/V·s (average of 58.2 ± 2 cm2/V·s), subthreshold slope of <120 mV/decade (average of 129 ± 12 mV/decade), and current on/off ratio of >5 × 1010. Various electrical characterization and technological computer-aided design simulation were performed to establish a plausible mechanism explaining enhanced mobility and Vth regulation in the ITO/a-IGZO TFTs. Additionally, systematic stability tests and spectroscopic analysis were carried out to evaluate the operational stability of the device, and it is suggested that Sn ion diffusing from ITO to the heterogeneous interface can be responsible for enhanced stability by reducing the oxygen vacancy defects.

Effect of oxygen defect on the performance of Nd: InZnO high mobility thin-film transistors

High mobility and stability are eternal themes for oxide semiconductor TFT. However, there is a natural contradiction between mobility and stability. The oxygen defect state has a great influence on oxide semiconductor devices, so we adopt different sputtering oxygen percentages to prepare Nd: InZnO films of different deposition states. The type and number of oxygen defects were extracted and fitted by μ-PCD, XPS, and CV. Through a series of characterization tests on thin films and devices, the influence mechanism of oxygen-related defect states on the performance and instability of high mobility oxide TFT was analyzed. The results show that the stability of TFT can be improved by appropriately increasing the oxygen percentage, but some mobility will be lost. Finally, we have achieved devices with high mobility and good stability by cleverly designing homojunction TFT. The best device performance is μsat=38.2 cm2V–1S–1, SS= 0.13 V/dec, Vth≈ 0 V, Ion/off= 4.3 × 108. This is a simple and effective way to prepare high-performance TFT circuits.

(La,Ba)SnO3 -based Thin-Film Transistors: Large-Signal Model and Scaling Projections

Perovskite oxides are extremely interesting for their possible use in high-mobility thin-film transistors (TFTs) suitable for high-performance large-area circuits. Here we present a semianalytical model of a recently fabricated TFT based on ${\mathrm{La}\text{\ensuremath{-}}\mathrm{Ba}\mathrm{Sn}\mathrm{O}}_{3}$, and explore the possibilities for technology optimization and the intrinsic potential of the device concept for applications in transparent and flexible electronics. We show that ${\mathrm{La}\text{\ensuremath{-}}\mathrm{Ba}\mathrm{Sn}\mathrm{O}}_{3}$ TFTs can outperform existing TFT device technologies through a detailed benchmarking exercise, and that these devices can be promising for display electronics and for a broader range of applications.

Interface roughness and interface roughness scattering in amorphous oxide thin-film transistors

In amorphous oxide semiconductors, rough interfaces influence transport in two main ways: changing the trap distributions and interface roughness scattering. Interface roughness scattering is expected to become important in high-mobility semiconductors in which charge transport takes place through a combination of trapping and band transport. Interface roughness scattering is quantitatively analyzed for amorphous oxide thin-film transistors (TFTs) within the framework of the Boltzmann transport equation. It is shown to be the main mobility limiting mechanism at room temperature under the conditions when carrier concentration is high and the interface is rough. The use of the precise extent of wavefunction overlap with the interface is important and the use of a finite potential barrier height at the insulator–semiconductor interface leads to more accurate calculations. The specific semiconductors considered are zinc tin oxide and indium gallium zinc oxide. It is shown that the consideration of interface roughness scattering can become important in evaluating transport in high-mobility TFTs.

Significant improvement of 2,9-DPh-DNTT organic thin-film transistors based on organic heterojunction buffer layer

High-mobility thin film transistors of para-sexiphenyl (p-6P)/2,9-diphenyl-dinaphtho[2,3-b:2′,3′-f]-thieno[3,2-b] thiophene (2,9-DPh-DNTT) are demonstrated by employing copper hexadecafluorophthalocyanine (F16CuPc), cobalt (II) hexadecafluoro-phthalocyanine (F16CoPc) and molybdenum oxide (MoO3) as buffer layers. The highest field-effect mobility of 9.3 cm2/Vs is achieved by using the F16CoPc buffer layer, which is the highest reported mobility for polycrystalline 2,9-DPh-DNTT thin film transistors. The improvement of the device performance is due to reducing device contact resistance between metal electrodes and the organic semiconductor and improving the carrier injection. Based on the optimized results, we fabricated an OTFT array consisting of p-6P/2,9-DPh-DNTT OTFTs with F16CoPc as the buffer layer by photolithography. A high mobility of 2.7 cm2/Vs and a low VT of −2.3 V are achieved which proved that 2,9-DPh-DNTT is an excellent organic semiconductor in the field such as a large-area display and sensor matrix, etc.

Realization of low-power and high mobility thin film transistors based on MoS2 layers grown by PLD technique

Molybdenum disulfide (MoS2) layers have been successfully grown and optimized for the realization of low power thin film transistors (TFTs) using catalysis free, economical and environment-friendly pulsed laser deposition (PLD) technique on comparably large sized passivated silicon (SiO2/Si) substrate of area 1.2 cm×1.0 cm. Growth of MoS2 monolayer is confirmed by reflection high-energy electron diffraction (RHEED), Raman spectroscopy, photoluminescence (PL) analysis and atomic force microscopy (AFM). The effect of planar electrodes of different metal system (Au/Ag, Pt/Ti, Al, Ni) on the electrical characteristics of MoS2 layers have been inspected in detail. Au/Ag bilayer system proved to be the best electrode for efficient charge injection into the MoS2 layers. A Back-gated field effect transistor (FET) was fabricated with Au/Ag was used as source-drain contacts and MoS2 as the semiconducting channel has been successfully developed. The fabricated transistor shows an accumulation electron mobility around 44.6 cm2 V-1s−1, current ION/OFF ratio of 1.4×105, subthreshold slope of nearly 360 mV/dec, interface trap density of 1.18×1012 /cm2eV and robust current saturation at lower Vds, suggesting that fabricated devices can be used in making low power switching devices.

New Low-Voltage Driving Compensating Pixel Circuit Based on High-Mobility Amorphous Indium-Zinc-Tin-Oxide Thin-Film Transistors for High-Resolution Portable Active-Matrix OLED Displays

In recent years, active-matrix organic light-emitting diodes (AMOLEDs) has been the most popular display for portable application. To satisfy the requirement for the application of the portable display, the design of the compensating pixel circuit with the low-voltage driving and low-power consumption will be requested. In addition to the circuit with the design of the low-voltage driving, high-mobility thin-film transistors as driving device will be also necessary in order to supply larger driving current at low-voltage driving. Therefore, the study presents a new low-voltage driving AMOLED pixel circuit with high-mobility amorphous indium–zinc–tin–oxide (a-IZTO) thin-film transistors (TFTs) as driving device for portable displays with high resolution. The proposed pixel circuit can simultaneously compensate for the threshold voltage variation of driving TFT (ΔVTH_TFT), OLED degradation (ΔVTH_OLED), and the I-R drop of a power line (ΔVDD). By using AIM-Spice for simulation based on fabricated a-IZTO TFTs with mobility of 70 cm2V−1S−1 as driving devices, we discovered that the error rates of the driving current were all lower than 5.71% for all input data when ΔVTH_TFT = ±1 V, ΔVDD = 0.5 V, and ΔVTH_OLED = 0.5 V were all considered simultaneously. We revealed that the proposed 5T2C pixel circuit containing a high-mobility a-IZTO TFT as a driving device was suitable for high-resolution portable displays.

Mobility and threshold voltages comparison of zinc nitride-based thin-film transistor fabricated on Si and glass

The present work reports the fabrication and characterization of high mobility thin-film transistors, where zinc nitride is used as the active layer (∼100 nm thick). For the TFT, the active layer was deposited at room temperature on different substrates (Si-p type and glass) by RF magnetron sputtering method and annealed at 350 °C post-fabrication and HfO2 was used as the gate insulation layer (∼50 nm thick). The obtained value of field-effect mobility was greater than 5 cm2 Vs−1, with optical bandgap ∼3.07 eV. The two MIS (metal insulator semiconductor) structures were analyzed using I–V and C–V measurements. It is demonstrated that Zinc Nitride is a potential candidate to be used as an active layer in TFT fabrication. The threshold voltages of the device built on Si and glass substrates were obtained as 0.8 volts and 2.6 volts respectively.

Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors

Metal-oxide thin-film transistors (TFT) fabricated by spray pyrolysis are of increasing interest because of its simple process and scalability. A bottleneck issue is to get a bubble-free and dense material. We studied the effect of ammonium acetate (AA) addition in the oxide precursor solution on the performance of spray-coated ZnO TFTs. AA acts as a stabilizer, which increases the solubility of the solution and enhances the film quality by reducing the defects. With AA addition in ZnO precursor, the films are coffee ring free with high mass density and better grain orientation. The ZnO TFT with AA exhibit a remarkable improvement of its device performance such as saturation mobility increasing from 5.12 to 41.53 cm2V−1s−1, the subthreshold swing decreasing from 340 to 162 mV/dec and on/off current ratio increasing from ~105 to 108. Additionally, the TFTs show excellent stability with a low threshold voltage shift of 0.1 V under gate bias stress. Therefore, the addition of AA is a promising approach to achieve high-performance ZnO TFTs for low-cost manufacturing of displays.

Transparent Flexible High Mobility TFTs Based on ZnON Semiconductor With Dual Gate Structure

High mobility thin film transistors (TFTs) based on zinc oxynitride (ZnON) semiconductor were fabricated onto polyethylene-2.6-naphthalate (PEN) substrates. The application of a dual gate structure enhanced the field-effect mobility from 65.8 to 147 cm2/ $\text{V}\cdot \text{s}$ , which is generally attributed to the bulk accumulation effect. Dual gate driving also results in improved device stability with respect to bias and illumination stress. This is most likely due to the fact that the bulk channel confines the charge carriers away from the semiconductor-dielectric interfaces, where charge trapping is anticipated. The electrical performance of dual gate devices did not change significantly after 5,000 bending cycles, while the single gate transistors exhibited clear degradation.

Hydrogen Barrier Properties of Atomic Layer Deposited Al2O3 with Different Oxidants for Ingazno Thin Film Transistor

Amorphous In-Ga-Zn-O (a-IGZO) semiconductors have been used as an active channel material in high mobility, flexible, and transparent thin film transistors (TFTs), but it is highly influenced by the external environment. Many factors could affect TFT performance, such as moisture, oxygen, and hydrogen, etc. Among them, hydrogen incorporation into the oxide semiconductor is unavoidable due to the high electronegativity of oxygen. Hydrogen incorporated into a-IGZO acts as a shallow donor by ionizing and bonding with oxygen to form hydroxyl groups, so that it makes the oxide TFT conductive and causes it not to show an on/off property.[1] Hydrogen can be incorporated through various processes, such as diffusion from ambient atmosphere, incorporation during the deposition of encapsulation layer, and diffusion from adjacent layer during post-annealing, etc. In particular, it has been observed that a large amount of hydrogen atoms produced by SiH4 plasma is incorporated into the a-IGZO layer, creating a shallow electron donor, when PE-CVD SiNx layer is deposited for encapsulation. [2] Thus, an appropriate hydrogen barrier is essential to prevent the inflow of hydrogen to the a-IGZO layer during the subsequent process. Therefore, a method of preventing hydrogen incorporation by chemical combination should also be performed. However, there is no systematic study to prevent hydrogen incorporation. The analysis of hydrogen atomic behavior in thin films with different properties have not been clearly examined so far, thus further studies for this are necessary. Techniques commonly used for the deposition of gas diffusion barrier deposition are sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD). Among them, ALD is considered as the most promising method to produce the gas diffusion barrier for the encapsulation due to its special features, such as conformal deposition, defect-free, high-quality layer and excellent uniformity.[3], [4] Since the ALD process is based on sequential self-limiting surface reaction where growth occurs by depositing the material layer by layer, thin films with various properties can be obtained depending on the materials (precursor and reactant) used for deposition as well as the thermodynamic conditions.[5] In this study, Al2O3 was deposited on the a-IGZO TFT by atomic layer deposition (ALD) using trimethylaluminum (TMA) with water or O3, as the precursor and oxidant, respectively, at low temperature (about 60 °C). First, we fundamentally investigated the characteristics of Al2O3 according to the oxidant. The chemical composition of the Al2O3 was different depending on the oxidant used in the ALD process (XPS, FT-IR measurement). Based on this, we analyzed the effect of these characteristics on hydrogen barrier properties by using transfer curve (I-V measurement) and stress test of device. As a result, the device in which the Al2O3 was deposited exhibited excellent hydrogen barrier properties as compared with the bare device. There was no device degradation after the hydrogen treatment, which suggested the possibility of enhancing the stability by effectively blocking hydrogen in various fields and device reliability in mass production in the future. Reference [1] S. I. Oh, G. Choi, H. Hwang, W. Lu, and J. H. Jang, “Hydrogenated IGZO thin-film transistors using high-pressure hydrogen annealing,” IEEE Trans. Electron Devices, vol. 60, no. 8, pp. 2537–2541, 2013. [2] A. Sato et al., “Amorphous In-Ga-Zn-O thin-film transistor with coplanar homojunction structure,” Thin Solid Films, vol. 518, no. 4, pp. 1309–1313, 2009. [3] J. Meyer et al., “Al2O3/ZrO2Nanolaminates as ultrahigh gas-diffusion barriersa strategy for reliable encapsulation of organic electronics,” Adv. Mater., vol. 21, no. 18, pp. 1845–1849, 2009. [4] A. Dameron, S. Davidson, B. Burton, P. Carcia, R. McLean, and S. George, “Gas diffusion barriers on polymers using multilayers fabricated by Al2O3 and rapid SiO2 atomic layer deposition,” J. Phys. Chem. C, vol. 112, pp. 4573–4580, 2008. [5] S. M. George, A. W. Ott, and J. W. Klaus, “Surface Chemistry for Atomic Layer Growth,” J. Phys. Chem., vol. 100, no. 31, pp. 13121–13131, 1996. Figure 1

Sequential lateral crystallization of amorphous silicon on glass by blue laser annealing for high mobility thin-film transistors

We report the thickness effect of amorphous silicon for the polycrystalline silicon (poly-Si) layer laterally crystallized by blue laser annealing (BLA) using 50 μs melting time. The grain size is much larger and full width at half-maximum of Raman intensity is lower compared to those of the poly-Si by excimer laser annealing. It is found that the average width of lateral grain is wider than 3 μm and full width of half maximum of Raman intensity for the BLA poly-Si with an optimum thickness of 90 nm is 3.32 cm−1. The p-type poly-Si thin-film transistor with 90 nm exhibits field-effect mobility of 161.91 ± 6.14 cm2/Vs and subthreshold swing of 227 ± 7 mV/dec.

High-Mobility IGZO TFTs by Infrared Radiation Activated Low-Temperature Solution Process

This letter presents high-mobility thin-film transistors (TFTs) based on InGaZnO by a novel infrared (IR) radiation activated low-temperature solution process. A high mobility of over 60 cm2V−1s−1, an ${I}_{\mathrm{\scriptscriptstyle ON}}/{I}_{\mathrm{\scriptscriptstyle OFF}}$ ratio of 106, and a decreased operating voltage of 4 V were achieved at 230 °C. This mobility was four times higher than that of a device by high-temperature (450 °C) annealing, and was comparable to those of oxide TFTs previously produced via vacuum or high-temperature processes. The synergistic IR radiation and thermal energy mechanism resulted in more effective removal of precursor impurities, a more extensive metal-oxygen lattice, and more oxygen vacancies to serve as charge carriers, which contributed to the much higher performance achieved with IR radiation. Moreover, the IR-processed devices exhibited excellent operational stability with a small ${V}_{\textsf {th}}$ shift under bias stress. Our results may provide new low-temperature solution routes to high-performance TFTs.

Atmospheric plasma-enhanced spatial-ALD of InZnO for high mobility thin film transistors

In this manuscript, the authors investigate the growth of indium zinc oxide, indium zinc oxide (InZnO, IZO) as a channel material for thin-film transistors. IZO is grown at atmospheric pressure and a high deposition rate using spatial atomic layer deposition (S-ALD). By varying the ratio of diethylzinc and trimethylindium vapor, the In/(In + Zn) ratio of the film can be accurately tuned in the entire range from zinc oxide to indium oxide. Thin film transistors with an In to Zn ratio of 2:1 show high field-effect mobility—exceeding 30 cm2/V s—and excellent stability. The authors demonstrate large scale integration in the form of 19-stage ring oscillators operating at 110 kHz. These electrical characteristics, in combination with the intrinsic advantages of atomic layer deposition, demonstrate the great potential of S-ALD for future display production.

Dual role of Ag nanowires in ZnO quantum dot/Ag nanowire hybrid channel photo thin film transistors.

High mobility and p-type thin film transistors (TFTs) are in urgent need for high-speed electronic devices. In this work, ZnO quantum dot (QD)/Ag nanowire (NW) channel TFTs were fabricated by a solution processed method. The Ag NWs play the dual role of dopant and providing the charge transfer route, which make the channel p-type and enhance its mobility, respectively. The best sample yields an on/off ratio (Ion/Ioff) of 5.04 × 105, a threshold voltage (VT) of 0.73 V, a high field effect mobility (μFE) of 8.69 cm2 V−1 s−1, and a subthreshold swing (SS) of 0.41 V dec−1. Owing to the strong ultraviolet (UV) absorption and photo-induced carrier separation ability of ZnO QDs and the fast carrier transport of Ag NWs, the devices acquire a high external quantum efficiency (EQE) and ultra-fast response under 365 nm UV illumination. The UV-modulated ZnO QD/Ag NW hybrid channel photo TFTs have potential for future application in optoelectronic devices, such as photodetectors and photoswitches.

Effect of Al2O3 Passivation Layer and Cu Electrodes on High Mobility of Amorphous IZO TFT

In this paper, we present a high mobility amorphous indium-zinc-oxide (a-IZO) thin film transistor (TFT) based on copper (Cu) source/drain electrodes (S/D) and aluminum oxide (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) passivation layer (PVL). The mechanism of high mobility for the a-IZO TFT based on Cu S/D with Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL was proposed and experimentally demonstrated. The sputtering of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL induced a highly conductive channel layer due to the formation of In-rich layer on the back channel. Also, Cu S/D presented Schottky contact behavior compared with Mo S/D which behaved like Ohmic contact. Because the Schottky contact can block leakage current and the highly conductive channel achieved high on-current, the a-IZO TFT based on Cu S/D and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL performed remarkable saturation mobility up to 412.7 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs. This paper presents a feasible way to implement high mobility TFT arrays with Cu electrodes.