PECVD a—Si：H薄膜对TFT有源矩阵性能的影响及其淀积工艺研究

分析了a－Si：HTFT有源层──a－Si：H薄膜质量和厚度对于a－Si：HTFT关键性指标（通断电流比、阈值电压、响应时间、开口率）的影响，深入、详细地研究了PECVD衬底温度、RF功率和频率、气体流量和反应室气压等淀积工艺参数对a—Si：H薄膜组分、结构的影响，并在实验的基础上给出了它们之间的关系曲线，确定了最佳淀积工艺参数，从而获得了高性能的7.5cm372×276象素a－Si：HTFT有源矩阵。     

Triode PECVD氢稀释制备的nc-Si:H薄膜的新结果

采用三极管型等离子体增强化学汽相淀积（TriodePECVD）系统，适当选取硅烷（SiH4）和氢气（H2）流量比制备纳米硅（nc-Si：H）薄膜．保持栅极偏压为－100V，改变SiH4、H2流量比可以得到薄膜从非晶硅（a－Si：H）到nc－Si：H的结构转变，其氢气流量比例[H2]／（[H2]＋[SiH4]）的阈值为93．3％．随着流量比进一步增大，晶化比例从12％增大至50％，但晶粒尺寸基本保持不变，nc－Si晶粒的平均尺寸约2．5nm，这是不同于常规二极管PECVD、氢稀释制备的nc－Si：H薄膜的新结果，并从实验上验证了电导率和电子迁移率的渗流现象．     

驱动AM-OLED的2-a-Si∶H TFT的设计与制作

a-Si∶H/SiNx∶HTFT在长时间栅偏应力作用下,会产生阈值电压漂移,这主要是由绝缘层电荷注入和有源层亚稳态产生而引起的。针对电荷注入现象,文章首先通过控制源气体SiH4和NH3流量的不同,利用PECVD制作了不同N/Si比(0.87～1.68)的氮化硅绝缘材料,对其进行了椭偏、红外和光电子散射能谱(EDS)测试。制作了不同的MIS结构电容,对其进行老化实验和C-V测试分析,结果表明稍富氮(N/Si比稍大于标准Si3N4的化学计量比1.33)的氮化硅做成的MIS样品在老化前后C-V曲线偏移不是很明显,表明其缺陷态密度相对较小,能够有效减小半导体/绝缘层界面间的电荷注入。设计了驱动OLED的2-a-Si∶HTFT像素电路及其阵列版图,优化了电路中的几个关键参数,即T1的W/L=2.5、T2的W/L=25和存储电容Cs=0.8pF。运用7PEP生产工艺,制作了13cm(5.2in)的TFT阵列样品。对TFT进行I-V特性测试,其开态电流为10μA,开关比为106;对AMOLED显示屏样品进行了静态驱动下的亮度测试,其最高亮度为341cd/m2。     

PECVD生长nc—Si：H薄膜的结构与物性研究

采用H2稀释SiH4和PECVD工艺，在严格控制衬底温度、射频功率、SiH4／H2气体分压比、反应室平衡气压和直流负偏压等各种工艺参数条件下，成功地在c－St、石英和玻璃衬底上沉积了nc－St：H膜。拉曼散射、X射线衍射（XRD）和高分辨率电子显微镜（HRE则研究证实，nc七i五膜具有一些新颖的结构特征，即该膜层由大量E制无序的3i微晶粒组成，其平均晶粒大小为人一3～6urn，晶态比约占整个膜层体积的53士5％。同时膜层中包含有大量的晶间界面，界面区厚度约为2～4个原子层，界面区内贮存有大量的H原子。对nc．St：H膜中的电子传导机制研究…     

TFT晶体管电学测量与耐压性研究

文章用RF—PECVD设备制备了G—SiNx薄膜,研究了TFT器件击穿电压的测定与分析方法,并对成膜条件中的SiH4流量以及G-SiNx膜厚进行浮动变化,以及研究TFT器件击穿电压的变化方式。结果表明：随着SiH4／NH3流量增大,其耐压性降低;增大绝缘膜厚度,耐压性随之增大。文章对TFT耐压性测量方法的探讨以及PECVD工艺条件与耐压性的相关关系的研究。对于制备合格的氮化硅薄膜提供了借鉴与指导。     

驱动AM-OLED的2-a-Si:H TFT的设计与制作

a-Si：H／SiNx：H TFT在长时间栅偏应力作用下，会产生阈值电压漂移，这主要是由绝缘层电荷注入和有源层亚稳态产生而引起的。针对电荷注入现象，文章首先通过控制源气体SiH4和NH3流量的不同，利用PECVD制作了不同N／Si比（0．87～1．68）的氮化硅绝缘材料，对其进行了椭偏、红外和光电子散射能谱（EDS）测试。制作了不同的MIS结构电容，对其进行老化实验和C-V测试分析，结果表明稍富氮（N／Si比稍大于标准Si3N4的化学计量比1．33）的氮化硅做成的M1S样品在老化前后C-V曲线偏移不是很明显，表明其缺陷态密度相对较小，能够有效减小半导体／绝缘层界面间的电荷注入。设计了驱动OLED的2-a-Si：H TFT像素电路及其阵列版图，优化了电路中的几个关键参数，即T1的W／L=2．5、T2的W／L=25和存储电容Cs=0．8pF。运用7PEP生产工艺，制作了13cm（5．2in）的TFT阵列样品。对TFT进行I-V特性测试，其开态电流为10μA，开关比为10^6；对AMOLED显示屏样品进行了静态驱动下的亮度测试，其最高亮度为341cd／m^2。     

p-Si TFT栅绝缘层用SiNx薄膜界面特性的研究

以NH3和SiH4为反应源气体,在低温下采用射频等离子体增强化学气相沉积(RF-PECVD)法在多晶硅(p-Si)衬底上沉积了SiNx薄膜.系统地分析讨论了沉积温度、射频功率、反应源气体流量比对SiNx薄膜界面特性的影响.分析表明,沉积温度和射频功率主要是通过影响SiNx薄膜中的si/N比和H含量影响薄膜的界面特性,而NH3/SiH4流量比则主要通过影响薄膜中的H含量影响薄膜界面特性.实验制备的SiNx薄膜层中的固定电荷密度、可动离子密度、SiNx与p-si之间的界面态密度分别达到了1.7×1012/cm2、1.4×1012/cm2、3.5×1012/(eV·cm2),其界面特性达到了制备高质量p-si TFT栅绝缘层的性能要求.     

厚度对a—Si：H薄膜性能的影响

用等离子体增强化学气相沉积法在最佳工艺参数下在硼玻璃基片上沉积了厚度为1μm以下的不同厚度的a-Si:H薄膜。测量了薄膜厚度对它的光电性质的影响。结果表明，当膜厚增加时，a-Si:H薄膜暗电导、光电导和阈值电压增大，光学带隙和Raman谱的TA模与TO模峰值比减小，折射率几乎不变，光吸收系数和通断电流比先增大，达到最大值后又减小。     

a—Si：H和a—SixH1—x：H光学特性的研究

本文所用a-Si:H和a-SixN1-x:H薄膜是用辉光放电法制备而成的,薄膜中氮含量由淀积气体中氮气与硅烷气体体积比γ(=N2/SiH4)来控制,利用椭圆偏振光谱测定了a-Si:H和a-SixN1-x:H在波长为200A-6000A的范围内的光学常数.着重研究了其光学参数随制备时的衬底温度T和γ而变化的变化规律.     

Characteristics and Electrical Properties of SiNx：H Films Fabricated by Plasma-Enhanced Chemical Vapor Deposition

SiNx：H films with different N/Si ratios are synthesized by plasma-enhanced chemical vapor deposition （PECVD）. Composition and structure characteristics are detected by Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）. It indicates that Si-N bonds increase with increased NH3/SiH4 ratio. Electrical property investigations by I-V measurements show that the prepared films offer higher resistivity and less leakage current with increased N/Si ratio and exhibit entirely insulating properties when N/Si ratio reaches 0.9, which is ascribed to increased Si-N bonds achieved.     

Dependence of Threshold Voltage of a-Si:H TFT on a-SiNx:H Film^①

The relation between threshold voltage for hydrogenated amorphous silicon thin film transistors(a-Si:HTFTs)and deposition conditions for hydrogenated amorphous silicon nitride(a-SiNx:H)films is investigated.It is observed that the threshold voltage,Vth,of a-Si:HTFT increases with the increase of the thickness of a-SiNx:H film,and the threshold voltage is reduced apparently with the increase of NH3/SiH4 gas flow rate ratio.     

Dependence of Threshold Voltage of a-Si:H TFT on a-SiN_x:H Film

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A novel a-Si:H AMOLED pixel circuit based on short-term stress stability of a-Si:H TFTs

This letter presents a novel pixel circuit for hydrogenated amorphous silicon (a-Si:H) active matrix organic light-emitting diode displays employing the short-term stress stability characteristics of a-Si:H thin film transistors (TFTs). The pixel circuit uses a programming TFT that is under stress during the programming cycle and unstressed during the drive cycle. The threshold voltage shift (V/sub T/-shift) of the TFT under these conditions is negligible. The programming TFT in turn regulates the current of the drive TFT, and the pixel current therefore becomes independent of the threshold voltage of the drive TFT.     

薄有源层非晶硅薄膜晶体管特性的研究

本文研究了薄ａ－Ｓｉ：Ｈ有源层结构的ａ－Ｓｉ：Ｈ ＴＦＴ的特性，实验结果表明，当ａ－Ｓｉ：Ｈ层的厚度小于一个临界值时，ａ－Ｓｉ：Ｈ厚度的变化对ａ－Ｓｉ：Ｈ ＴＦＴ静态特性的影响明显增大，本文中详细分析了有源层背面空间电荷层对ａ－Ｓｉ：Ｈ ＴＦＴ特性的影响，从表面有效空间电荷层的概念出发，从理论上分析了有源层厚度与阈值电压的关系，计算的临界有源层厚度为１３０ｎｍ，这与实验结果基本一致。     

Effect of Film Thickness on Properties of a—Si：H Films

The a -Si:H film with different thickness smaller than 1μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition contitions.The effect of diferent thickness on film properties is analyzed.The results show that,with the increase of the film thickness,the dark conductivity ,photoconductivity and threshold voltage increase,the optical gap and peak ratio of TA to TO in the Raman spectra decrease, the refractive index keeps almost constant, and the optical absorption coefficient and current ration of on/off state first maximize and then reduce.     

在a-Si:H/a-SiN_x:H超晶格中导电机制的研究(英文)

We have studied the conduction mechanism of a series of a-Si:H/a-SiNx:H multi-layers samples which have an identical sublayer thickness and periodic numbers, except the ratio of N/Si in a-SiNx:H sublayers. It is shown that the temperature characteristic of conductivity of these samples has a kink point in the range of 120-140℃. The kink temperature and the acttivation energy of conductivity are related to the N/Si ratio in the a-SiNx:H sublayers. We recognized preliminarily that the mechanism above and below the kink temperature could be the bulk or the interfacial conduction in a-Si:H well layers.     

Hydrogenated amorphous silicon thin-film transistor with a thingate insulator

Thinning the gate insulator in an hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) has been studied in a coplanar structure. The threshold voltage decreases with decreasing gate insulator thickness without changing the field effect mobility significantly. The reduction in the threshold voltage is due to the decrease in the charge traps in the SiN_x and in its film thickness. The coplanar a-Si:H TFT with a gate insulator thickness of 35 nm exhibited a field effect mobility of 0.45 cm²/Vs and a threshold voltage of 1.5 V. The thickness of the gate insulator can be decreased in the coplanar a-Si:H TFTs because of the planarized gate insulator     

AMOLED电流镜像像素电路的稳定性分析

a—Si：HTFT在长时间施加直流栅偏压下将导致晶体管闽值电压漂移,造成OLED的发光亮度下降,影响其使用寿命。而多管的像素电路设计可以补偿或消除阂值电压的漂移。本文分析了电流控制电流镜像像素电路的工作原理。结合a—Si：HTFT阈值漂移模型仿真了电路在长时间工作下阈值漂移对驱动电流稳定性的影响,并提出了相应的解决办法。研究结果表明合理的像素电路设计可以有效改善驱动电流的稳定性。     

Estimate Threshold Voltage Shift in a-Si:H TFTs Under Increasing Bias Stress

A method of estimating threshold voltage shift in hydrogenated amorphous silicon (a-Si:H) transistors under increasing bias stress is proposed. Although the threshold voltage shift in a-Si:H thin-film transistor (TFT) has been modeled well under constant bias stress, its property with increasing bias stress, which occurs in many a-Si:H-based compensating circuits, still cannot be quantified without any restriction, such as constant overdrive bias or short stressing time. In this paper, we propose a model which is effective under an arbitrary increasing stress for a prolonged time. The proposed model reduces to the constant bias model if the stress bias remains unchanged. With this method, the lifetime of most compensating circuits based on a-Si devices can be estimated completely.