Recombination Efficiency and Width in Bilayer Organic Light-emitting Devices

A bilayer model with ohmic anode contact and injection limited cathode contact has been proposed to calculate the recombination efficiency and recombination zone width of the device. The effects of the thickness of hole transport layer and the barriers of organic/organic interface on the combination efficiency and recombination width have been discussed. It is found that： （1） When the electrons are blocked fully and the holes are not blocked significantly at the organic/organic interface, for a given Lh/L, the recombination efficiency increases with increasing the applied voltage, but at a higher applied voltage, the recombination efficiency decreases with increasing Lh/L; （2） The recombination efficiency increases with increasing applied voltage and Hh＇, and when applied voltage and Hh＇ exceed some value, the recombination efficiency appears as a plateau; （3） The recombination width decreases with increasing the applied voltage and Lh/L. This model might explain the relative experiment phenomena.     

具有栅电流修正的肖特基势垒技术测量迁移率分布

砷化镓肖特基场效应管有源层中的电子迁移率分布对器件有重要的影响,改变负栅偏压可以测出不同深度处的迁移率,但是由于表面总是处在耗尽状态,因此很难测出表面电子迁移率,本文介绍一种微分直流等效模型,使肖特基势垒可以正偏且较好地包括了栅电流修正.应用这一模型,可以较精确地测出非常接近表面的漂移迁移率和几何磁阻迁移率,模型推导较严密,物理意义清晰.     

Hole Mobility in Poly (N-vinylcarbazole) Thin Film Based on Silicium

ＨｏｌｅＭｏｂｉｌｉｔｙｉｎＰｏｌｙ（Ｎ－ｖｉｎｙｌｃａｒｂａｚｏｌｅ）ＴｈｉｎＦｉｌｍＢａｓｅｄｏｎＳｉｌｉｃｉｕｍ①②ＣＨＥＮＢａｉｊｕｎ，ＷＡＮＧＸｉａｏｗｅｉ③，ＬＩＵＳｈｉｙｏｎｇ（ＳｔａｔｅＫｅｙＬａｂ．ｏｎＩｎｔｅｇｒａｔｅｄＯｐｔｏｅ...     

Hole Mobility in Poly（N—vinylcarbazole） Thin Film Based on Silicium^①②

The mobilities of holes in thin,spin-casting films of poly( N -vinylcarbazole)(PVK) based on silicium are measured using a time-of-flight (TOF) technique.The drift of hole mobility is strongly dependent on the electric field and temperature.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of hole is 7.14×10 -6 cm 2·V -1 ·s -1 ,in a 200 nm thick sample.     

Electron Mobility in Tris（8—Hydroxyquinolinolato）Aluminum Thin Film Based on Silicium^①②

We have measured the mobilities of electrons in thin,vapor-deposited films of tris(8-hydroxyquinolinolato) aluminum(Alq 3) based on silicium using a time-of-flight(TOF) technique.The drift of electron mobility is strongly electric field and temperature dependent.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of electron is 1.0×10 -5 cm 2·V -1 ·s -1 for 200 nm thick sample.     

注入和复合对单层有机发光器件电致发光效率的影响

考虑电荷的注入、无序系统中载流子的输运及极化子激子的解离和复合过程,建立了单层有机电致发光器件电致发光效率的理论模型.计算并讨论了离化距离对器件复合效率以及注入和复合对器件电致发光效率的影响.结果表明:(1) 通过降低金属/有机物界面势垒可以显著提高器件的EL效率;(2)当两电极均为欧姆接触或一个电极欧姆接触,一个电极是接触限制时,在低场下EL效率由注入决定,而高场下复合起主要作用;(3)当两电极均为接触限制时,EL效率主要由注入过程来决定.此模型可以较好地解释一些实验现象.     

Accurate Extraction of Schottky Barrier Height and Universality of Fermi Level De-Pinning of van der Waals Contacts

Due to Fermi level pinning (FLP), metal-semiconductor contact interfaces result in a Schottky barrier height (SBH), which is usually difficult to tune. This makes it challenging to efficiently inject both electrons and holes using the same metal—an essential requirement for several applications, including light-emitting devices and complementary logic. Interestingly, modulating the SBH in the Schottky–Mott limit of de-pinned van der Waals (vdW) contacts becomes possible. However, accurate extraction of the SBH is essential to exploit such contacts to their full potential. In this study a simple technique is proposed to accurately estimate the SBH at the vdW contact interfaces by circumventing several ambiguities associated with SBH extraction. Using this technique on several vdW contacts, including metallic 2H-TaSe₂, semi-metallic graphene, and degenerately doped semiconducting SnSe₂, it is demonstrated that vdW contacts exhibit a universal de-pinned nature. Superior ambipolar carrier injection properties of vdW contacts are demonstrated (with Au contact as a reference) in two applications, namely, a) pulsed electroluminescence from monolayer WS₂ using few-layer graphene (FLG) contact, and b) efficient carrier injection to WS₂ and WSe₂ channels in both n-type and p-type field effect transistor modes using 2H-TaSe₂ contact.     

偏压对溅射ITO膜载流子浓度和迁移率的影响

研究了基体偏压对 ITO 膜载流子浓度和迁移率影响的机理,并就载流子浓度和迁移率随偏压变化的实验结果与理论结果作了比较,两者基本吻合。获得了n_e=3.2×10~(20)cm~(-3),U_H=50cm~2V~(-1)s~(-1)的 ITO 膜。     

异构网络中基于角度移动模型的垂直切换率分析

异构网络中终端的移动特性是无线资源分配的一个重要因素,本文给出了一种终端的角度移动模型,分析了该模型下终端移动的方向角特点。根据终端移动的方向角特点,推导了用户在固定的时间间隔T内运动方向不变时的切换率闭合公式,并将时间间隔T趋于零时的切换率的理论极限值作为一个特例,从切换率的理论极限值可以明显看出,切换率与用户分布密度、用户移动速度以及小区半径之间的关系,通过切换率的计算说明了在一定条件下,小区内用户数是动态平衡的。然后进一步推导了异构网络中垂直切换率的闭合公式,并仿真证明了理论分析的正确性。仿真结果表明,在终端移动方向改变频繁、终端移动速率很低或者小区半径足够小时,可以利用切换率的理论极限值来近似实际切换率,这样可以有效降低理论计算切换率的复杂度。     

发射区复合对AlGaAs／GaAsHBT特性的影响

采用将发射区体内复合及表面复合归一化为载流子寿命变化的方法，用一维模拟程序，能简便地研究发射区复合对ＡｌＧａＡｓ／ＧａＡｌＨＢＴ特性的影响，计算结果表明，发射区载流了寿命的变化几乎不影响注入到基区的电子电流，但却成反比例地影响基区空穴电流，由于降低寿命增大了空穴复合电流，从而降低了ＨＢＴ的电流增益。     

用微波光电导谱研究半导体薄片的少子扩散长度和表面复合速度

当半导体薄片同时受到微波和光照射时,通过样品的微波传输系数与光的波长有关,当光的波长连续地变化时,微波传输系数也连续地变化。本文分析了在半导体薄片中的少子扩散长度、少子寿命及表面复合速度与上述微波传输系数的变化△T之间的关系,并通过测量半导体薄片的微波光电导谱计算这些参数。研究表明,可以从微波光电导谱中的△T的峰值位置直接算出少子扩散长度。这是一种无接触、无损伤的快速测试方法,测试区域是直径为3mm的一个圆斑,样品可以在测试台上自由移动。本方法的测试结果与其它方法所得的结果是较为一致的。     

电子元器件及电路的剂量率效应测试技术研究

介绍了半导体器件与电路的剂量率效应及其测试方法。主要分析了分立器件和集成电路的效应机理和建立的光电流测试系统及瞬时回避测试系统,给出了在晨光号加速器和DPF辐照装置上三极管及瞬时回避开关电路的辐照效应测量结果。     

温度和剂量率对NMOS器件迁移率的影响

对加固型ＣＣ４００７ＮＭＯＳ器件进行了低温（－３０℃）和室温（２５℃）γ射线辐射实验、不同剂量率下的γ辐射实验以及不同温度下的退火实验。根据实验结果，利用归一化迁移率与界面态电荷的机理模型，分析了辐射环境温度、辐射剂量率以及退火温度对ＮＭＯＳ器件迁移率的影响。     

Mechanisms of device degradation in organic solar cells: Influence of charge injection at the metal/organic contacts

Organic solar cells suffer from device degradation under various undesirable ambient conditions, which limits their efficiencies and applications a lot. The frequently appeared S-shaped current density–voltage (J–V) characteristics just reflect this effect and make its underlying mechanisms even obscurer for experimentalists. By performing device model simulation, we investigate the J–V curves of a organic bulk heterojunction solar cell for different interfacial charge injection conditions. We find the S-shaped kinks appear when both electron and hole injection barriers exceed 0.3 eV, which is attributed to the shortage of dark injection carriers. For the nearly Ohmic contacts, the open circuit voltage is significantly reduced. The quantitative study suggests it arising from the majority carrier accumulation and the induced local field variation at the vicinity of the contacts. S-shaped kink is gradually eliminated with increasing carrier mobilities. Finally, we find the decreasing of fill factor under enhanced light absorption, which results from the drastic bimolecular recombination and thus signifies remarkable internal losses.     

低轨卫星网小区移动性对切换的影响

低轨卫星网络点波束覆盖布局与用户相对运动方向决定了用户在小区间的切换关系,并直接影响用户切换性能。该文针对两种典型的小区运动模式建立了移动模型,分析了驻留时间、切换概率和平均切换次数等移动性指标,并结合具体的信道分配策略分析比较了小区移动性对用户切换性能的影响。结果表明在小区低重叠度的条件下小区运动模式Ⅱ的用户切换性能优于模式Ⅰ,更适用于低轨卫星网络,为低轨卫星点波束的布局提供了参考。     

Relation between injection barrier and contact resistance in top-contact organic thin-film transistors

We theoretically investigate the carrier injection into top-contact bottom-gate organic thin film transistors. By means of a two-dimensional drift–diffusion model, we explicitly consider thermionic and tunneling injection in combination with subsequent carrier transport into the device. Based on numerical simulations with this model, we determine the contact resistance as a function of the nominal hole injection barrier height and temperature. Depending on the barrier height or the operating temperature, we find three distinct injection regimes. Our work reveals that in all three regimes self-regulating processes exist due to which the influx of current is adjusted according to the needs of the channel at the given point of operation.     

磷酸和酒石酸在GSI阻挡层CMP抛光液中的应用

在阻挡层的化学机械平坦化(CMP)过程中,Cu与阻挡层去除速率的一致性是保证平坦化的关键问题之一。低k介质材料的引入要求阻挡层在低压力下用弱碱性抛光液进行CMP,这给抛光液对不同材料的选择性提出了新的挑战。研究了低压2 psi,(1 psi=6.89 kPa)CMP条件下,磷酸和酒石酸作为阻挡层抛光液pH调节剂对Cu和Ta的络合作用。实验结果表明,酒石酸对Cu和Ta有一定的络合作用,能够提高它们的去除速率;磷酸能提高Ta的去除速率,而对Cu的去除有抑制作用。最终在加入磷酸浓度为2×10-2mol/L,酒石酸浓度为1×10-2mol/L,H2O2体积分数为0.3%,pH=8.5时,Cu/Ta/SiO2介质的去除速率选择比达到了1∶1∶1,去除速率约为58 nm/min;同时,磷酸和酒石酸的加入能够有效改善Cu的表面状态。     

恒流源在输油管线冰堵位置测定的应用

北方冬季气温一般在—15℃~—30℃左右,在冰冻期内,脱水不完全或者蜡质过高的油气在输送过程中,部分水或蜡质会在油气管线或气管线内壁凝聚,造成管内介质流动孔径变小,严重时会造成管道局部冰堵,从而导致全线停输,若不能及时处理将会造成巨大的经济损失。以应变片的应力应变特性利用电桥的加减特性,通过检测变送电路在管线加压过程中冰堵位置前后管内介质压力不同,致使冰堵点前后管道变形程度也不同,通过传感器来捕捉冰堵前后管道的变形程度,从而判断冰堵点的位置,是一种相比传统检测方法(如钻孔法、敲击法、理论数值分析法、超声波法等)较为高效的测量方法。     

不同荧光蓝光层厚度的OLED的制备与光电性能

采用蓝色荧光材料1p-TDPVBi结合绿色磷光材料2Ir(ppy)3掺杂到母体材料CBP作为绿光发光层,并且采用3BPhen作为电子传输层和激子阻挡层制备结构为ITO/m-MTDATA(50nm)/NPB(10nm)/p-TDPVBi(dnm)/CBP∶Ir(ppy)38%7nm/BPhen(60nm)/LiF(1nm)/Al的有机发光器件。实验结果表明:通过改变蓝光发光层p-TDPVBi的厚度,得到了高效率的有机发光器件,当p-TDPVBi厚度为5nm时,器件的电流效率和功率效率在4V时达到32.3cd/A和25.3lm/W,亮度在11V时达到31 020cd/m2。研究了p-TDPVBi厚度由3nm变化到9nm,OLED器件的电流密度-电压特性曲线、亮度-电压曲线及电流效率-电压和功率效率-电压等光电性能的变化。     

彩色PDP喷砂工艺喷头速率控制公式和均匀性控制研究

研究和引入了彩色PDP的喷砂工艺均匀性控制方法和喷头速率控制公式.均匀性控制研究表明增加喷砂次数,同时减小步进距离,或采用喷头阵列是提高喷砂工艺均匀性的有效措施.喷头速率控制公式给出了单次喷砂和多遍喷砂及喷头阵列和单喷头的喷头移动速率之间的关系.采用多个喷头的阵列适合工业化大生产.而长条形喷头更有利于提高喷砂工艺的均匀性.