Papers by Keyword: Thin Film Transistor

Abstract: We fabricated and studied the electrical characteristics of thin-film transistors with an amorphous zinc-tin–oxide (a-ZTO) channel, which was deposited by radio frequency magnetron co-sputtering under different oxygen partial pressures. The effect of varying the oxygen concentration on the electrical properties and device performance of the a-ZTO TFTs was investigated. A positive shift observed in the threshold voltage with increasing oxygen suggests that the number of oxygen vacancies in the a-ZTO film decreased. With an oxygen flow rate of 4 %, a threshold voltage of 2.25 V, an on-off current ratio of 2.1 × 10³, and a subthreshold slope of 0.8 V·dec⁻¹ were obtained.

Abstract: We report on the fabrication of bottom gate thin film transistors with indium oxide (In2O3) thin films as the active channel layers. The films were deposited on SiO2/Si substrate at room temperature by direct current (DC) magnetron sputtering. The ITO films were used as source and drain electrodes. The In2O3 films were structurally characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results revealed that the films were amorphous in nature. Electrical measurement has revealed that the devices operate as an n-channel enhancement mode and exhibit an on/off ratio of 10⁶. The threshold voltage is-3V and the channel mobility on the order of 22.3 cm2/Vs has been determined.

Abstract: The properties of nanostructured aluminum (Al) doped zinc oxide (ZnO) thin film for thin film transistors (TFT) are presented. This research has been focused on optical and structural properties of Al doped ZnO thin film. The influence of Al doping concentration at 0~5 at.% on the Al doped ZnO thin film properties have been investigated. The thin films were characterized using UV-Vis-NIR spectrophotometer for optical properties. The surface morphology has been characterized using field emission scanning electron microscope (FESEM). The absorption coefficient spectra obtained from UV-Vis-NIR spectrophotometer measurement show all films have low absorbance in visible and near infrared (IR) region but have high UV absorption properties. The calculated Urbach energy indicated the defects concentrations in the thin films increase with doping concentrations The FESEM investigations shows that the nanoparticles size becomes smaller and denser as the doping concentration increase.

Abstract: The effect of Zinc-Oxide (ZnO) thin film annealed in different ambiences is presented. To achieve low cost and environmentally friendly process, ZnO aqueous solution is synthesized by dissolving zinc acetate dihydrate in deionized water directly. Zinc oxide aqueous solution of high solubility and stability is presented. High quality and dense Zinc oxide thin film is formed by spin coating. Annealing temperatures are in the range of 300 °C~500 °C, and annealing ambiences of both air and N2 are discussed.

Abstract: A nonvolatile memory thin-film transistor (MTFT) using an amorphous indium gallium zinc oxide (a-IGZO) semiconducting channel and a Ta₂O₅ gate insulator is proposed. The high-dielectric-constant material Ta₂O₅ was deposited by e-beaming and used for the charge storage layer, i.e., a metal-oxide-semiconductor (MOS) capacitor. We obtained memory windows (ΔV_th = 2 V) at 3-V gate voltage and realized reliable memory operations. Therefore, a-IGZO TFT with Ta₂O₅ can be employed in integrated high-performance nonvolatile memory devices for applications to transparent displays and flexible electronic devices.

Abstract: Density of states in the channel bulk area of a-Si:H thin-film transistors (TFTs) was extracted by using low-frequency noise analysis. The drain current noise power spectral density shows 1/ƒγ behavior at relatively high frequencies (ƒ > 1 kHz), which is due to the exponential distribution of tail states. For the analysis, the modified number fluctuation model which is correlated with mobility fluctuation was used. From the relationship (γ=1- kT/Et ) between exponent γ and the slope of exponential distribution Et of band tail states, the distribution of the band tail near conduction band was extracted.

Abstract: Large-scale fabrication of ZnO nanowire (NW) based devices with a low cost process is a key issue in practical application. In this paper, we report a simple and sufficient self-assembly process to prepare highly dense, uniform ZnO NW films. In this process, the NWs are modified with the aminopropyltriethoxy silane (APTES) to form the positively charged amine-terminated layer, so they are adsorbed on negatively charged SiO₂/Si substrates to form ZnO NW films by the electrostatic interaction in aqueous solution. Nanowire thin-film transistors (NW-TFTs) based on the prepared ZnO NW films are fabricated. A typical NW-TFT exhibited a current on/off ratio of 2.7×10⁵, a transconductance of 546 nS and a field-effect mobility of 8.9 cm²/V•s. This study may pave the way toward large-scale fabrication of ZnO NW based devices with simple, sufficient and low cost process.

Abstract: The fabrication of zinc oxide （ZnO）based thin-film field-effect transistors (TFTs) on p-Si substrates by rf magnetron sputtering, photolithography and wet etching processes was presented. Bottom-gate-type thin film transistors using ZnO as an active channel layer were constructed, and their properties were characterized by atomic force microscope, X-ray diffraction and I-V measurements. The fabricated ZnO transistors exhibited enhancement mode characteristics with the on-to-off current ratio of ∼105 and the threshold voltage of 10V. It is believed that the ZnO TFTs fabricatd by the simple and low-cost technique could be applicable to electronic devices.

Abstract: In our paper, we induced the process of ZnO based thin film transistors (ZnO-TFTs) fabricated on the substrate of glass. The photolithographic plate designed for using in the ZnO-TFT devices fabrication process was shown in our paper. The ZnO-TFT devices were fabricated successfully, the Ion/off ratio is ~104.

Abstract: Active matrices often related with high grade display devices, due to application of the storage elements, typically thin film transistor (TFT). Because of the complex procedures in the manufacturing TFT, investment of the high value manufacturing equipments and clarification plants is necessary, hence increasing the manufacturing cost of the flat panel, and more importantly, causing the pollution of water and air. As the contribution of TFT array merely exists in supplying storage function for the pixels of the display panel, large efforts have been made to find suitable cells that have bistable effect, so as to substitute the effect of TFT. As the bistable cell is just the storage pixel, one could construct a bistable cell to skip the needs of TFT active matrices. The paper is to introduce currently available bistable display devices in the following field: liquid crystal bistable displays with cholesteric liquid crystals, which is an example to introduce the bistable technology; iMod display devices based on mechanic induced bistable and light interference, which shows the possibility to construct bistable display; and the display based on solid powder movement in air or in vacuum, so called liquid powder displays, which shows how to improve the existed display.