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Investigation of Electrical Characteristics on LaAlO <sub/>3</sub> /ZrO <sub/>2</sub> /IGZO TFTs with Microwave Annealing
摘要： Conventional thin film transistor suffered from high threshold voltage, poor subthreshold swing, and high operation voltage. These shortcomings make the traditional thin film transistor does not meet the needs with the high-performance, high-resolution, low temperature and energy conservation nowadays. Due to the good selectivity of energy transformation and rapid heating rate, microwave annealing is promising to replace conventional furnace annealing and applied in the investigation. LaAlO3/ZrO2 is employed as gate electrode and gate dielectric layer for a-IGZO TFTs, under the premise that performance of a-IGZO TFTs without decreasing. With adjusting the power/time of microwave annealing, the effect on electrical characteristics of a-IGZO TFTs is investigated.
关键词： ZrO2,Microwave Annealing,a-IGZO TFTs,LaAlO3
更新于2025-09-23 15:23:52
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24.5: Back-Channel-Etched a-IGZO TFTs with TiO <sub/>2</sub> :Nb Protective Layer
摘要： A back-channel-etched (BCE) process for the fabrication of a-IGZO TFTs is demonstrated, in which conductive TiO2:Nb (TNO) thin film is used to serve as protective layer for the a-IGZO active layer. TNO film could excellently protect a-IGZO due to its ultra-small surface roughness. With treatment by N2O plasma + 200°C annealing, the conductive TNO can be converted into an insulator to serve as an in situ passivation layer. Besides, the TNO in the source–drain (S-D) region remain conductive due to the protection of S-D electrodes, which could be proved by the XPS results. Compare with the conventional device without TNO protective layer, the S-D parasitic resistance (RSD) of devices with 1 nm and 5 nm TNO is significantly reduced. The positive bias stress stability is improved as well for the devices with TNO in situ passivation layer.
关键词： amorphous indium gallium zinc oxide (a-IGZO),Nb doped TiO2 (TNO),thin film transistors (TFTs),back-channel-etched (BCE) process
更新于2025-09-23 15:23:52
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24.4: High Performance Top-gate Self-aligned Coplanar a-IGZO TFTs with Light Shielding Metal Design
摘要： The TG-SA a-IGZO TFTs with different light shielding metal (SM) layers design were demonstrated and compared in this paper. Their electrical characteristics have been measured in order to systematically analyze the effect that the SMs ever made on. The relationship between device instability and different SMs design have been systematically analyzed. Then the prototype 14” OLED display with an excellent performance using TG-SA a-IGZO TFTs backplane have been made successfully, which indicates an excellent mass-production prospect.
关键词： reliability,light shielding metal,top-gate self-aligned coplanar structure,a-IGZO TFTs
更新于2025-09-23 15:23:52
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Chemical bonds in nitrogen-doped amorphous InGaZnO thin film transistors
摘要： We investigated the chemical bonds in nitrogen-doped amorphous InGaZnO (a-IGZO:N) thin films with an X-ray photoelectron spectrometer (XPS). The doped nitrogen atoms preferentially combined with Ga cations and formed stable Ga-N bonds for low nitrogen-doping (N-doping), but additionally formed less stable In-N and Zn-N bonds for high N-doping. The stable Ga-N bonds and few defects made the variation in oxygen vacancy (VO) more difficult and hence achieved better stability of thin film transistors (TFTs) with low doped a-IGZO:N channel layers. Contrarily, the less stable In-N and Zn-N bonds as well as excess defects led to an easier change in VO and thus more unstable a-IGZO:N TFTs for high N-doping.
关键词： Amorphous InGaZnO (a-IGZO),Thin film transistors (TFTs),Nitrogen doping (N-doping),Chemical bonds
更新于2025-09-23 15:22:29
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - A Comparitive Study of On-Chip Clock Generators Using a-IGZO TFTs for Flexible Electronic Systems
摘要： This paper presents a comparitive study of ring oscillators (RO) using amorphous Indium Gallium Zinc Oxide (a-IGZO) thin-film transistors (TFTs) to implement on-chip clock generator for flexible electronic systems. A five-stage RO has been implemented with different inverter topologies using IGZO TFTs, which includes Diode connected load, Capacitive bootstrapping (BS), Pseudo-CMOS and Pseudo-CMOS bootstrapping architectures. These topologies have been simulated using in-house IGZO TFT models under similar conditions using different power supplies (10 V, 15 V and 20 V) in cadence environment. Among all architechtures Capacitive bootstrapping RO has ensured highest frequency of operation in the order of MHz and an output swing of 82% of VDD. Whereas, Pseudo-CMOS based RO provides the lowest power consumption in the order of μW with an output swing of 57% of VDD. On the other hand, the combination of Pseudo CMOS and bootstrapping has ensured highest voltage swing of 95% of VDD. In terms of power delay product (PDP) BS RO is superior with respect to other topologies. This work provides a clear insight to the designer to choose a particular topology for given application, mainly for on-chip clock generation for flexible electronic systems based on the requirements.
关键词： Bootstrapping,Ring Oscillator,Flexible on-chip clock generator,Pseudo-CMOS,a-IGZO TFTs
更新于2025-09-23 15:22:29
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A Fully Integrated 11.2 mm2 a-IGZO EMG Front-end Circuit on Flexible Substrate Achieving up to 41dB SNR and 29MΩ Input Impedance
摘要： A biopotential front-end circuit is designed and fabricated using a-IGZO TFTs on flexible plastic substrate. Its input chopper provides both noise reduction and Frequency Division Multiplexing among multiple front-ends in an array. Measurements of the front-end at chopping frequencies from 5 to 8 kHz show a gain in the range of 24.9 - 23.1 dB, bandwidth of 5.4 to 5.2 kHz, input noise in the EMG band ranging from 125 μVRM S to 31.4 μVRM S, and an input impedance of 29.6 to 23 M ?. At different chopping frequencies, the SNR in the EMG band is respectively 29, 32.3, 38, 41 dB, enough to monitor Muscle Fibre Conduction velocity. This is achieved in a total area of 11.2 mm2 and with 1.3 mW power consumption. In-vivo recordings of EMG from the forearm of a person using the fabricated front-end and standard gel electrodes have been performed. The measurements show EMG bursts with a maximum amplitude of 1.6 mV, which is within the physiological range for this muscle. The proposed circuit achieves an 8.9X reduction in size compared to previous front-ends fabricated on flexible foil for EMG applications, enabling a spatial resolution in the order of a few millimetres, with great benefit for the diagnosis of neuromuscular disorders.
关键词： IGZO,EMG,flexible electronics,Biomedical circuits,EHG
更新于2025-09-23 15:21:21
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Influence of Passivation Layers on Positive Gate Bias-Stress Stability of Amorphous InGaZnO Thin-Film Transistors
摘要： Passivation (PV) layers could effectively improve the positive gate bias-stress (PGBS) stability of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs), whereas the related physical mechanism remains unclear. In this study, SiO2 or Al2O3 films with different thicknesses were used to passivate the a-IGZO TFTs, making the devices more stable during PGBS tests. With the increase in PV layer thickness, the PGBS stability of a-IGZO TFTs improved due to the stronger barrier effect of the PV layers. When the PV layer thickness was larger than the characteristic length, nearly no threshold voltage shift occurred, indicating that the ambient atmosphere effect rather than the charge trapping dominated the PGBS instability of a-IGZO TFTs in this study. The SiO2 PV layers showed a better improvement effect than the Al2O3 because the former had a smaller characteristic length (~5 nm) than that of the Al2O3 PV layers (~10 nm).
关键词： thin-film transistor (TFT),positive gate bias stress (PGBS),passivation layer,characteristic length,amorphous InGaZnO (a-IGZO)
更新于2025-09-23 15:21:21
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Channel-Length Dependent Performance Degradation of Thermally Stressed IGZO TFTs
摘要： The focus of this work is on the performance degradation of thermally stressed IGZO TFTs with SiO2 for both the gate dielectric and back-channel passivation material. I-V characteristics of TFTs with bottom-gate (BG) and double-gate (DG) electrode configurations were observed to left-shift and degrade with thermal stress. Experimental results indicate the instability occurs either directly or indirectly due to the influence of H2O within the passivation oxide above the IGZO channel region. An atomic layer deposition (ALD) alumina capping layer applied immediately following the passivation oxide anneal was successful in improving thermal stability. Channel length dependence was observed where longer channel DG devices were more prone to degradation. A hypothesis has been developed with H2O as the expected origin of this phenomenon. Experiments have been specifically designed to establish the feasibility of the proposed mechanism. Furthermore, DG devices which exhibit enhanced thermal stability are presented.
关键词： thermal stability,SiO2 passivation,ALD alumina capping,IGZO TFTs,channel length dependence
更新于2025-09-23 15:21:01
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Two-step Degradation of a-InGaZnO Thin Film Transistors under DC Bias Stress
摘要： A unified explanation is proposed to consistently explain the two-step degradation of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) under DC positive bias temperature instability (PBTI) stress without or with different drain stress voltages (Vds). For PBTI stress without stress Vds, this initial negative Vth shift is believed to be induced by donor-like defect states corresponding to H2O molecule and intrinsic defects, while for PBTI stress with stress Vds, the negative shift is believed to be induced by donor-like defect states corresponding to oxygen vacancies. The gate-bias-induced electron trapping mechanism is responsible for positive Vth shift. These transitions from negative to positive Vth shift are resulted from the competition between the donor-like states creation and electron trapping.
关键词： PBTI,donor-like states creation,two–step degradation,electron trapping,IGZO TFTs,H2O molecule
更新于2025-09-23 15:21:01
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Enhanced UV-visible detection of InGaZnO phototransistors via CsPbBr3 quantum dots
摘要： Indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) exhibit high field-effect carrier mobility and low off-state current, which are attractive for high speed and low noise photodetectors and image sensor applications. However, with an optical band gap of ~3.3 eV, the photodetection range of IGZO TFTs is limited to short wavelength ultraviolet (UV) light. Here, we demonstrate a simple approach to enhance the performance of IGZO-based phototransistors by incorporating layers of solution-processed perovskite quantum dots (QDs) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Owing to the fast transfer of photogenerated electrons by CsPbBr3 QDs absorbing layer, the photoresponse of QD-decorated IGZO phototransistor is extended to the visible range (500 nm), and the responsivity and detectivity of QD-decorated device are more than two order higher than those of original IGZO TFTs. Moreover, the QD-decorated IGZO phototransistor also exhibits enhanced performance under UV light (350 nm), achieving a responsivity of 9.72 A/W, a detectivity of 2.96 × 1012 Jones, and a light to dark current ratio in the order of 106 at a wavelength of 350 nm (a light intensity of 207.3 μW/cm2).
关键词： heterojunction,CsPbBr3 QDs,IGZO,phototransistors
更新于2025-09-23 15:19:57