缓冲夹层影响异质结有机光伏器件性能研究

制备了结构为CuPc/缓冲层/C₆₀异质结的有机光伏器件,分别选用三氧化钼和红荧烯为缓冲层,研究了增加缓冲层对器件性能的影响.结果表明,增加三氧化钼和红荧烯缓冲层后器件的开路电压和光电转换效率都得到提高,器件的短路电流密度和填充因子都有所降低.开路电压从没有缓冲层时的0.39 V分别提高到0.58 V、0.55 V,转换效率从0.36%提高到0.44%,短路电流从1.92 mA/cm²分别降低到1.77 mA/cm²、1.81 mA/cm²,填充因子从0.48分别减少到0.43、0.44.进一步研究表明器件的短路电流密度受缓冲层厚度的影响很大,当缓冲层厚度很小时,器件短路电流密度还有所增加,但随着缓冲层厚度的增加,短路电流密度逐渐减小,当缓冲层厚度为10 nm时,器件短路电流密度减少到0.35 mA/cm².开路电压随着厚度的增加逐渐增加,从1 nm时的0.43 V增加10 nm时0.63 V.根据整数电荷转移模型和界面能级理论解释有机光伏器件开路电压提高以及短路电流密度减少的原因,为有机太阳能电池性能的改善提供了研究方法.     

缓冲夹层影响异质结有机光伏器件性能研究

制备了结构为CuPc/缓冲层/C60异质结的有机光伏器件,分别选用三氧化钼和红荧烯为缓冲层,研究了增加缓冲层对器件性能的影响.结果表明,增加三氧化钼和红荧烯缓冲层后器件的开路电压和光电转换效率都得到提高,器件的短路电流密度和填充因子都有所降低.开路电压从没有缓冲层时的0.39V分别提高到0.58V、0.55V,转换效率从0.36%提高到0.44%,短路电流从1.92mA/cm2分别降低到1.77mA/cm2、1.81mA/cm2,填充因子从0.48分别减少到0.43、0.44.进一步研究表明器件的短路电流密度受缓冲层厚度的影响很大,当缓冲层厚度很小时,器件短路电流密度还有所增加,但随着缓冲层厚度的增加,短路电流密度逐渐减小,当缓冲层厚度为10nm时,器件短路电流密度减少到0.35mA/cm2.开路电压随着厚度的增加逐渐增加,从1nm时的0.43V增加10nm时0.63V.根据整数电荷转移模型和界面能级理论解释有机光伏器件开路电压提高以及短路电流密度减少的原因,为有机太阳能电池性能的改善提供了研究方法.     

氧化锌作为电子传输层的量子点发光二极管

为降低量子点发光二极管(QLED)的开启电压,提高器件性能,利用电子传输性能良好的氧化锌(ZnO)作为电子传输层,制备了结构为ITO/PEDOT∶PSS/poly-TPD/QDs/ZnO/Al的QLED样品。在该器件结构基础上,采用隧穿注入和空间电荷限制电流模型仿真分析了载流子在量子点(QDs)层的电流密度。研究发现,当ZnO厚度为50 nm时,poly-TPD的理论最优厚度为40 nm,载流子在QDs层的注入达到相对平衡。通过测试器件的电流密度-电压-亮度-发光效率特性,研究了空穴传输层厚度对QLED器件性能的影响。实验结果表明,当空穴传输层厚度为40 nm时,器件的开启电压为1.7 V,最大发光效率为1.18 cd/A。在9 V电压下,器件最大亮度达到5 225 cd/m~2,远优于其他厚度的器件。实验结果与仿真结果基本吻合。     

人体静电放电对有机发光二极管的影响

研究了静电放电（ESD）人体模式（HBM）下的脉冲应力对有机发光二极管（OLED）的性能及寿命的影响,并讨论了相应的物理机制。对比分析了4组OLED在施加ESD放电为0,200,800,1 600 V前后的电学和光学特性,并进行了相应的寿命测试分析。研究发现,OLED器件的光谱对ESD不敏感,随着冲击电压的增大,由于静电打击对载流子的短期抑制效应,OLED的亮度出现轻微下降。在静电冲击电压为200 V和800 V时,伏安特性没有发生变化;当静电冲击电压增至1 600 V时,反向漏电有明显增加。后续的加速寿命实验表明,静电打击对器件的工作寿命没有明显的规律性影响,但是会一定程度提高非本质老化失效的概率。     

基于双电荷层结构的CMOS单光子雪崩二极管

基于180nm标准CMOS工艺,设计了一种能够有效提高光子探测效率的双电荷层结构的单光子雪崩二极管.该器件结构采用P电荷层和逆行掺杂的深N阱形成PN结,选取不同的P电荷层掺杂浓度,对击穿电压进行优化,当P电荷层浓度为1×1018cm-3时,击穿电压为17.8V,电场强度为5.26×105 V/cm.进一步研究发现N电荷层的位置会影响漂移电流密度和扩散电流密度.当在深N阱与N隔离层交界处掺杂形成N电荷层,即N电荷层掺杂峰值距离器件表面为2.5μm时,器件性能最优.通过Silvaco TCAD仿真分析得到:在过偏压1V下,波长500nm处的探测效率峰值为62%,同时在300～700nm范围内的光子探测效率均大于30%.     

双空穴注入的绿色磷光有机电致发光器件

制作了一种新型绿色磷光有机电致发光二极管。器件结构为ITO/HAT-CN(x nm)/MoO3(30 nm)/NPB(40 nm)/TCTA(10 nm)/CPB∶GIr1(30 nm,14%)/BCP(10 nm)/Alq3(25 nm)/LiF(1 nm)/Al(100 nm),其中X=0,8,10,12,14,15 nm。电流密度-电压-亮度特性表明该结构有利于降低驱动电压和增加器件亮度。当HAT-CN厚度为12 nm时,器件的最高亮度可以达到32 480 cd/m2,起亮电压为3.5 V左右,发光效率为24.2cd/A。所设计的空穴型器件证明该器件结构具有很好的空穴注入和传输特性。     

磁绝缘线振荡器的起振电压与注入电压关系的分析

粒子模拟和实验研究发现磁绝缘线振荡器(MILO)的起振电压会随注入工作电压的增大而增大, 通过进一步的分析与研究, 找到了引起该现象的根本原因, 即随着注入工作电压的增大, 工作电压上升前沿的斜率必然增大, 上升前沿斜率的增大必然引起起振电压的增大, 当斜率无限大时, MILO的起振电压等于工作电压. 因此, 工作电压上升前沿斜率的变化是引起MILO器件起振点变化的根本原因; 当注入电压上升沿的斜率固定不变时, 同一MILO器件的起振点不变, 即对应的起振电压值不变; 当注入电压上升沿的斜率增大时, 同一MILO器件的起振点对应的起振电压值随之增大. 对MILO器件的自磁绝缘临界电流公式进行了部分修正. 关键词： 磁绝缘线振荡器 工作电压 起振电压 工作曲线     

室温下溅射法制备高迁移率氧化锌薄膜晶体管

为降低氧化锌薄膜晶体管(ZnO TFT)的工作电压,提高迁移率,采用磁控溅射法在氧化铟锡(ITO)导电玻璃基底上室温下依次沉积NbLaO栅介质层和ZnO半导体有源层,制备出ZnO TFT,对器件的电特性进行了表征。该ZnO TFT呈现出优异的器件性能:当栅电压为5 V、漏源电压为10 V时,器件的饱和漏电流高达2.2 m A;有效场效应饱和迁移率高达107 cm~2/(V·s),是目前所报道的室温下溅射法制备ZnO TFT的最高值,亚阈值摆幅为0.28 V/decade,开关电流比大于107。利用原子力显微镜(AFM)对NbLaO和ZnO薄膜的表面形貌进行了分析,分析了器件的低频噪声特性,对器件呈现高迁移率、低亚阈值摆幅以及迟滞现象的机理进行了讨论。     

双极型晶体管在强电磁脉冲作用下的瞬态响应

 利用时域有限差分法,对双极型晶体管在强电磁脉冲作用下的瞬态响应进行了2维数值模拟,分析了器件烧毁过程中电场、电流密度、温度等参数的分布及变化情况,分别观察了低电压和高电压脉冲作用下烧毁过程中热点的形成过程,并得到了器件烧毁所需时间以及能量与脉冲电压幅度之间的关系。在电压脉冲较低时,烧毁点位于通道中靠近集电极的位置,当脉冲电压达到一定幅度的时候,由于发射极与集电极之间发生雪崩击穿,基极和发射极之间电势会抬高,从而引起基极和发射极之间的击穿,形成新的热点,并在电压幅度约高于100 V的情况下会率先达到烧毁温度。随着脉冲电压幅度的增高,晶体管烧毁所需时间呈负指数减少,而所需能量在55~100 V之间接近于线性增长,直到电压幅度约高于100 V时才开始减少。     

偏置条件对SOINMOS器件总剂量辐照效应的影响

本文研究了0．8μmSOINMOS晶体管，经剂量率为50rad（Si）／s的60Coγ射线辐照之后的总剂量效应，分析了器件在不同辐照条件和测量偏置下的辐照响应特性．研究结果表明：器件辐照时的栅偏置电压越高，辐照后栅氧化层中积累的空穴陷阱电荷越多，引起的漏极泄漏电流越大．对于漏偏置为5V的器件，当栅电压大于阈值电压时，前栅ID-VG特性曲线中的漏极电流因碰撞电离而突然增大，体电极的电流曲线呈现倒立的钟形．     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.