The Effect of Oxygen Partial Pressure during Active Layer Deposition on Bias Stability of a-InGaZnO TFTs

The effect of oxygen partial pressure （Po2） during the channel layer deposition on bias stability of amorphous indium-gallium-zinc oxide （a-IGZO） thin film transistors （TFTs） is investigated. As Po2 increases from 10% to 30%, it is found that the device shows enhanced bias stress stability with significantly reduced threshold voltage drift under positive gate bias stress. Based on the x-ray photoelectron spectroscopy measurement, the concentration of oxygen vacancies （Or） within the a-IGZO layer is suppressed by increasing Po2. Meanwhile, the low-frequency noise analysis indicates that the average trap density near the channel/dielectric interface continuously drops with increasing Po2. Therefore, the improved interface quality with increasing Po2 during the channel layer deposition can be attributed to the reduction of interface Ov-related defects, which agrees with the enhanced bias stress stability of the a-IGZO TFTs.

基于SOI材料α-Si:H TFTs的制作和特性研究(英文)

采用RF-PECVD系统在SOI材料上制作α-Si:H TFT,纳米非晶硅薄膜厚度为98nm,沟道长宽比为10μm/40μm。用扫描电子显微镜、X射线衍射和拉曼光谱等检测方法对不同退火温度下的氢化非晶硅薄膜形貌进行了表征。采用CMOS工艺、各向异性腐蚀溶液EPW、射频溅射技术和等离子体刻蚀等工艺实现α-Si:H TFT的制作。在给出一般α-Si:H TFT特性分析和实验结果的基础上,又采用建模方式对α-Si:H TFT出现的负阻特性进行研究。提取纳米氢化非晶硅薄膜与栅氧化层界面处能带图的结果表明,在靠近漏端0.5μm范围内,漏压由6V增加到30V时,随漏压的增加,价带能量逐渐下降。研究结果表明,距离漏端0.5μm范围内的压降导致负阻特性产生。

Mobility impact on compensation performance of AMOLED pixel circuit using IGZO TFTs

The suitability of indium gallium zinc oxide(IGZO) thin-film transistors(TFT) for implementation of active matrix display of organic light emitting diodes(AMOLED) compensation pixel circuits is addressed in this paper. In particular, the impact of mobility on compensating performance for the implementation in AMOLED pixel circuits is investigated. Details of the effective mobility modeling using the power law of gate-to-source voltage are provided, and parameters are extracted according to the measured current-to-voltage data of IGZO TFT samples. The investigated AMOLED pixel circuit consists of 4 switching TFTs, 1 driving TFT, and 1 capacitor. A "source-follower" structure is used for the threshold voltage extraction of the driving transistor. A new timing diagram is proposed; thus the current error of the pixel circuit is almost independent of the effective mobility. But, to improve the precision of the threshold voltage extraction of the driving transistor, the mobility is required to be greater than5 cm^2 V^(-1) s^(-1). On the other hand, the optimized storage capacitance is reversely proportional to the effective mobility. Thus, the layout area of the pixel circuit can be decreased from 100 × 100 to 100 × 68 μm2, with the effective mobility increased from 10 to50 cm^2 V^(-1) s^(-1). Therefore, IGZO TFT is a good alternative backplane technology for AMOLED displays, and a higher effective mobility is preferred for high compensation performance and compact layout.

双层结构对ZnO TFT稳定性的影响

室温下采用射频磁控溅射方法在SiO_(2)/Si衬底上沉积了单层ZnO薄膜和高氧/低氧双层ZnO薄膜,采用电子束蒸发设备蒸镀Al电极,制备单沟道ZnO TFTs和双层沟道ZnO TFTs。比较两种结构ZnO TFTs的各种性能参数,分析双层结构对TFTs产生的影响。实验结果表明,底部高含氧量ZnO层和顶部低含氧量ZnO层构成了DAL同质结且高氧/低氧薄膜存在载流子浓度产差,利用载流子从高浓度向低浓度扩散的性质,可以填补栅介电层和沟道层之间的界面态缺陷,使器件界面类受主陷阱减少,有效降低TFTs的滞回现象。与单有源层TFTs相比,双沟道层TFTs还具有电学调制作用,其电学性能和稳定性均有明显的提高,得到最佳TFTs的开/关电流比达到3.44×10^(9),亚阈值摆幅为0.68 V/dec,阈值电压偏移为1.2 V。

不同宽长比的柔性LTPS TFT的电应力可靠性

为了研究不同宽长比的柔性低温多晶硅薄膜晶体管(LTPS TFT)的电应力可靠性,测试了器件的I-V特性,以表征器件在强电场直流应力下由于自热效应和热载流子效应带来的电学性能退化。通过瞬态电流法表征了器件在强电场直流应力下的时间常数谱,并对其产生的新陷阱进行定位,分析了产生陷阱的内在机理。结果表明,在相同的强电场直流应力下宽长比为3/2.5的器件,其电学参数变化最大,自热效应以及热载流子效应带来的影响也最大。自热效应导致器件性能退化的主要原因是较大的栅源电压导致Si/SiO2界面处和栅氧化层中的陷阱增多,而热载流子效应导致器件性能退化的主要原因则是由于较大的漏源电压使得漏极晶界陷阱态密度急剧升高。

An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is pro- posed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.

一种高动态对比度显示屏技术研究

文章以12.3英寸车载显示屏为研究对象,通过直下式背光分区设计及测试结果,实现显示屏高动态对比度,提升显示屏显示效果。并针对不同分区方案,通过LED、芯片选型、OD值、Pitch值、成本等方面研究分区控制差异,为此技术搭载车辆应用提供参考依据。

四灰阶快刷电子纸显示技术分析

针对现有快刷电子纸产品在显示成像中颜色单一及快刷多次时白色亮度降低的问题,提出了四灰阶快刷电子纸的显示技术,从四灰阶快刷电子纸工作原理、驱动波形算法进行分析,研究分析了四灰阶快刷电子纸纸膜性能和TFT背板的性能设计,为电子纸行业技术更新提供参考价值。

LVDS车载应用传输质量分析

介绍了高速视频信号低压差分信号(low voltage differential signaling,LVDS)在薄膜晶体管(thin film transistor,TFT)液晶显示屏(liquid crystal display,LCD)模组中受到的影响因素及改善方向。基于车载显示屏中的印刷电路板(printed circuit board,PCB)及柔性电路板(flexible printed circuit,FPC)信号传输线进行阻抗匹配,分析LVDS在PCB到FPC跨介质传输后,FPC长度对LVDS造成失真畸变,其原因为寄生电容变化导致容性反射,进而引起信号非单调性。在FPC长度较长且电磁兼容性(electro magnetic compatibility,EMC)需求较高的情况下,将LVDS从L型走线改为T型走线,可改善LVDS眼图的质量。

Poly-Si TFTs integrated gate driver circuit with charge-sharing structure

A p-type low-temperature poly-Si thin film transistors（LTPS TFTs） integrated gate driver using 2 nonoverlapped clocks is proposed.This gate driver features charge-sharing structure to turn off buffer TFT and suppresses voltage feed-through effects.It is analyzed that the conventional gate driver suffers from waveform distortions due to voltage uncertainty of internal nodes for the initial period.The proposed charge-sharing structure also helps to suppress the unexpected pulses during the initialization phases.The proposed gate driver shows a simple circuit,as only 6 TFTs and 1 capacitor are used for single-stage,and the buffer TFT is used for both pulling-down and pulling-up of output electrode.Feasibility of the proposed gate driver is proven through detailed analyses.Investigations show that voltage bootrapping can be maintained once the bootrapping capacitance is larger than0.8 pF,and pulse of gate driver outputs can be reduced to 5μs.The proposed gate driver can still function properly with positive V（TH）shift within 0.4 V and negative V（TH） shift within-1.2 V and it is robust and promising for high-resolution display.

AGZO薄膜晶体管的制备及其光电特性

通过磁控共溅射的方法在热氧化SiO 2衬底上沉积了铝镓共掺杂氧化锌(AGZO)薄膜,并且制备了底栅型结构的AGZO薄膜晶体管(AGZO TFTs),分析不同Al靶材溅射功率对薄膜的表面形貌、粗糙度以及透射率和光学带隙的影响,研究AGZO TFTs的电学性能和紫外探测性能.实验结果表明,AGZO薄膜在可见光区域平均透过率均超过95%,并且可以通过控制Al靶材的溅射功率调控薄膜的光学带隙.当Al靶材溅射功率为20 W时,制备所得的AGZO TFTs的电学性能最优,其阈值电压为0.96 V,电流开关比达到了2.3×107.同时,AGZO TFTs的光电性能也较为优良,在365 nm的紫外光照射下,其响应度为105.9 A/W,光暗电流比为7.7×105,探测度为1.46×1012 Jones.

TFT基板低功耗显示驱动方法研究

TFT的低功耗特性能够减少电子设备的能量消耗,从而达到节省能源、延长电池寿命、降低使用设备温度、提高显示质量的目的。因此,低功耗TFT在电子设备的设计和制造中具有十分重要的作用。TFT基板的结构有很多种类,通常可分为一般型、高温多晶硅型、低温多晶硅型、金属氧化物半导体型和柔性材料基板型。本文对现有的TFT基板显示器件的低功耗研究进行总结分析,主要包括两大方面:对TFT基板本身驱动进行优化;对TFT基板外设驱动进行优化。本文对两大方面的低功耗研究进行了综述,并对近年来国内外TFT低功耗方法研究进行详细介绍。根据所介绍的方法的特点与其尚未攻克的困境,对TFT基板显示设备低功耗驱动的未来发展进行了展望。

Fluorination-mitigated high-current degradation of amorphous InGaZnO thin-film transistors

As growing applications demand higher driving currents of oxide semiconductor thin-film transistors(TFTs),severe instabilities and even hard breakdown under high-current stress(HCS)become critical challenges.In this work,the triggering voltage of HCS-induced self-heating(SH)degradation is defined in the output characteristics of amorphous indium-galliumzinc oxide(a-IGZO)TFTs,and used to quantitatively evaluate the thermal generation process of channel donor defects.The fluorinated a-IGZO(a-IGZO:F)was adopted to effectively retard the triggering of the self-heating(SH)effect,and was supposed to originate from the less population of initial deep-state defects and a slower rate of thermal defect transition in a-IGZO:F.The proposed scheme noticeably enhances the high-current applications of oxide TFTs.

柔性薄膜晶体管在传感器领域的研究进展

当今的电子产品正面临着颠覆性的演变,从笨重刚性设备发展到轻巧、柔软和灵活的设备,甚至需要生物相容性和可生物降解等。薄膜晶体管(TFT)是构成柔性电子的最常见的有源薄膜器件之一,在可穿戴和纺织集成系统、表皮设备和机器人人造皮肤等领域具有巨大潜力。首先介绍了TFT的种类和制备方法,对比了真空法和溶液法两者的优缺点;接着从TFT各功能层出发,包括绝缘层、半导体层和电极,对比了无机金属氧化物和聚合物材料体系,并总结了柔性TFT在传感器领域的研究进展和应用;最后,提出了柔性TFT在传感器领域存在的难点和问题,对其应用进行了展望。

退火温度对溶液法制备IGZO-TFT器件性能影响

随着人们进入信息时代,半导体技术快速发展,对薄膜晶体管(Thin film transistor,简称TFT)的性能要求逐渐提高.IGZO由于具有较高的载流子迁移率、相对良好的均匀性等优势而受到广泛关注;而传统的真空技术制备薄膜晶体管,因制备工艺复杂、制备成本高等问题,在快速发展的信息时代逐渐显露出局限性,本文采用制备工艺更为简单的溶液法在Si/SiO_(2)基底上制备IGZO有源层薄膜,并测试不同退火温度(450℃,550℃,650℃)条件下对薄膜性能的影响.结果表明,适当提高退火温度可以有效改善IGZO-TFT器件的电学性能,本实验测试得出:当溶液法制备薄膜在550℃退火温度下退火器件性能最优,溶液法制备的器件电流开关闭达到105,器件性能相对比较稳定.

Atomic layer deposition for nanoscale oxide semiconductor thin film transistors:review and outlook

Since the first report of amorphous In–Ga–Zn–O based thin film transistors,interest in oxide semiconductors has grown.They offer high mobility,low off-current,low process temperature,and wide flexibility for compositions and processes.Unfortunately,depositing oxide semiconductors using conventional processes like physical vapor deposition leads to problematic issues,especially for high-resolution displays and highly integrated memory devices.Conventional approaches have limited process flexibility and poor conformality on structured surfaces.Atomic layer deposition(ALD)is an advanced technique which can provide conformal,thickness-controlled,and high-quality thin film deposition.Accordingly,studies on ALD based oxide semiconductors have dramatically increased recently.Even so,the relationships between the film properties of ALD-oxide semiconductors and the main variables associated with deposition are still poorly understood,as are many issues related to applications.In this review,to introduce ALD-oxide semiconductors,we provide:(a)a brief summary of the history and importance of ALD-based oxide semiconductors in industry,(b)a discussion of the benefits of ALD for oxide semiconductor deposition(in-situ composition control in vertical distribution/vertical structure engineering/chemical reaction and film properties/insulator and interface engineering),and(c)an explanation of the challenging issues of scaling oxide semiconductors and ALD for industrial applications.This review provides valuable perspectives for researchers who have interest in semiconductor materials and electronic device applications,and the reasons ALD is important to applications of oxide semiconductors.

活体指纹采集仪的应用现状和技术创新

介绍当前基于光学、电容、超声波、无接触采集等新兴技术的活体指纹采集仪工作原理和应用现状,以及对实务工作的影响。基于TFT工艺的技术进步,使得活体指纹采集仪的体积可大大缩小、轻薄便携,并可通过智能手机等实现移动警务应用。展望了活体指纹采集仪的未来发展趋势。

一种带中控互联功能的7寸TFT屏组合仪表设计

本文主要介绍采用最新汽车电子技术,在7寸彩色TFT液晶屏平台上,通过采用CAN总线通信技术,开发出一款功能丰富、性能稳定、显示效果佳和人机交互体验良好的带中控互联功能显示的组合仪表。

浅析超薄玻璃基板发展现状及趋势

随着平板显示技术的飞速发展,其上游材料领域如玻璃基板、偏光片、光学膜等也在加速发展。玻璃基板作为显示的核心配件,无论是OLED、TFT还是LTPS都离不开对它的需求,本文简述了液晶玻璃基板的发展现状,以及对其发展趋势进行分析。

基于快刷电子纸显示的残影分析及优化方案

针对现有快刷电子纸产品在多帧刷屏后容易出现残影显示问题,从电子纸纸膜(FPL)、电子纸背板TFT设计、电子纸波形(WF)设计的角度进行深入分析产生残影现象原因,提出优化电子纸驱动系统最佳Vcom电压及优化快刷波形驱动算法的解决方案,并介绍了优化快刷波形驱动算法方案中减少刷屏次数算法和插入清屏波形算法两种方法。经实验验证,快刷显示的残影现象得到明显改善。