基于聚噻吩衍生物的异质结薄膜太阳能电池

近年来聚噻吩衍生物作为电子给体材料的异质结薄膜成为国内外研究的热点.讨论了异质结薄膜太阳能电池的工作原理,重点分析了材料、混合比例、制作工艺等对聚噻吩衍生物异质结薄膜太阳能电池性能的影响,并指出了今后聚噻吩衍生物异质结薄膜太阳能电池的发展方向.     

铁电薄膜与底电极之间界面的异质结效应

铁电薄膜与底电极之间由于高温扩散而形成了界面层，且观察到其对薄膜电性能的影响类似于硅衬底上铁电薄膜的异质结效应。基于能带理论的考虑，建立物理模型来解释其影响。该界面异质结模型不仅可以解释铁电薄膜的界面分层、电滞回线不对称等现象，而且还成功地解释了电滞回线中心在极化轴上的偏移和疲劳循环过程中的偏移增加，并探讨了这种偏移对铁电薄膜疲劳特性的影响。     

铁电薄膜与底电极之间界面的异质结效应

铁电薄膜与底电极之间由于高温扩散而形成了界面层，且观察到其对薄膜电性能的影响类似于硅衬底上铁电薄膜的异质结效应。基于能带理论的考虑，建立物理模型来解释其影响。该界面异质结膜型不仅可以解释铁电薄膜的界面分层、电滞回线不对称等现象，而且还成功地解释了电滞回线中心在极化轴上的偏移和疲劳循环过程中的偏移增加，并探讨了这种偏移对铁电薄膜疲劳特性的影响。     

n-BN/p-Si薄膜异质结的I-V特性

用射频溅射系统制备了BN薄膜,并且用离子注入的方法在BN薄膜中注入S,从而成功制备了n-BN/p-Si薄膜异质结,并研究了异质结的电学性质.注入S的BN薄膜是用13.56 MHz射频溅射系统沉积在p型Si(100)(5～6 Ω·cm)衬底上,靶材为h-BN靶(纯度为99.99%).离子注入时,注入离子的能量为190 keV,注入剂量为1015/cm2.对注入后的薄膜进行了退火处理(退火温度为600℃),用真空蒸镀法在异质结表面蒸镀了2 mm×5 mm的铝电极,以便测量掺杂后异质结的电学性质.实验结果表明离子注入掺杂后制备的n-BN/p-Si异质结的I-V曲线具有明显的整流特性,其正向导电特性的拟合结果表明异质结的电流输运符合"隧道-复合模型"理论.     

ZnSe—(Zn_(1-x)Cd_xTe)_(1-y)(In_2Te_3)_y薄膜异质结光电特性

近年来,不少科技工作者从结晶学方面对Ⅱ—Ⅵ族化合物异质结制作技术进行深入地研究,制成一些具有优良性能的从可见光到近红外范围的光电器件,并获得广泛应用。一般说来,形成异质结的条件是构成异质结的材料应具有良好的相容性,要求异质结界面处原子,排列相似。但实际上由于材料的晶格常数、电子亲和能及热膨胀系数等的差异,还有制作工艺质量问题,常常在异质结界面产生大量的悬挂键和缺陷,造成结界面能带的不连续,对异质结性能产生严重影响。我们用真空蒸发方法,以Ⅱ—Ⅵ族化合物ZnSe、ZnTe及CdTe等为材料,制成ZnSe—(Zn_(1-x)Cd_xTe)_(1-y)(In_2Te_3)_y(x=0.2～0.5,y=0.02～0.07)薄膜异质结。用这种异质结作摄象管靶或其它光电器件。从结晶学来看,上述三种材料都是闪锌矿结构,理论上可以形成异质结,但由于晶格失配率大,是一种晶格不匹配异质结。本文简单叙述并讨论这种异质结的一些光电特性。     

基于MEMS制作n-Zn0/p-Si异质结及特性

基于MEMS技术在P型<100>晶向双面抛光单晶硅片上制作c型硅杯,在C型硅杯上表面扩散P+,采用磁控溅射法在扩散区上制备择优取向为<0002>晶向的n-ZnO薄膜,形成n-ZnO/P-Si异质结.采用HP4280A型C-V特性测试仪分析n-ZnO/p-Si异质结的C-V特性,该异质结为突变结.采用HP4145B型半导体参数测试仪分析n-ZnO/p-si异质结,I-V特性,结果给出,n-ZnO/p-Si异质结在正向偏压下,电流随外加偏压按指数函数增加,反向电流不饱和,采用突变异质结的正反向势垒能带结构对其,I-V特性进行分析.     

用于Cu互连阻挡层的非晶Ni-Al薄膜研究

以非晶Ni-Al薄膜作为Cu互连的阻挡层材料,采用射频磁控溅射法构架了Cu/Ni-Al/Si的异质结.利用原子力显微镜、X射线衍射仪和四探针测试仪研究了不同温度下高真空退火样品的表面形貌、微观结构与输运性质.实验发现非晶Ni-Al薄膜在高达750℃的退火温度仍能保持非晶结构,各膜层之间没有明显的反应和互扩散存在,表明了非晶Ni-Al薄膜具有良好的阻挡效果,可以用作Cu互连的阻挡层材料.     

TiO_2/CdS异质结薄膜的制备及光生载流子传输机理研究

通过"刮刀法"和化学浴沉积法(CBD)相结合制备了TiO_2/CdS异质结薄膜。利用XRD、SEM、UV-Vis吸收光谱和Ⅰ-Ⅴ特征曲线等手段研究了沉积时间对异质结薄膜材料的形貌及性能的影响。结果表明当CdS的沉积时间为30min时,制备的TiO_2/CdS异质结薄膜具有最优的光电性能。利用EIS和TPV技术对光生载流子的传输过程进行了系统的研究,其结果表明其最优的光电性能主要归因于异质结构的构建可有效提高光生载流子分离的效率和传输的速度,并能显著提高光生载流子的寿命。     

高真空化学气相外延炉的研制

研制出满足Ｓｉ１－ｘＧｅｘ异质结薄膜材料生长工艺的高真空化学气相外延炉,介绍了Ｓｉ１－ｘＧｅｘ异质结薄膜材料的生长工艺,详述了该气相外延设备的性能指标、结构组成和设计原理,并且给出了利用该设备生长Ｓｉ１－ｘＧｅｘ异质薄膜的实验结果。     

p型ZnO薄膜研究进展

ZnO薄膜是一种应用广泛的半导体材料.近几年来,随着对ZnO的光电性质及其在光电器件方面应用的开发研究,ZnO薄膜成为研究热点之一.制备掺杂的p型ZnO是形成同质p-n结以及实现其实际应用的重要途径.近来已在p型ZnO及其同质结发光二极管(LED s)研究方面取得了较大的进展.目前报道的p型ZnO薄膜的电阻率已降至10-3Ω.cm量级.得到了具有较好非线性伏安特性的ZnO同质p-n结和紫外发光LED.本文就其最新进展进行了综述.     

CdTe thin film technology: Leading thin film PV into the future

CdTe is a near perfect material for PV application with a direct band gap of ～1.5 eV that is closely matched to the terrestrial solar spectrum and a high optical absorption coefficient where less than 1 μm thickness is adequate to absorb the incident light. CdTe thin film solar cell and module technology has validated the economies of scale that were projected for thin film PV technologies since the early 1980s where manufacturing costs are now below $0.84 with module efficiencies of 11.1%. Additionally, the low-temperature coefficient of CdTe modules results in a high annualized output. A critical issue for CdTe manufacturers is that there is not a clear pathway to increase the module performance to 15% or beyond based on current laboratory results and efficiency improvements will require fundamental improvements in the CdTe semiconductor properties and/or developing an alternative device structure.     

On the theory of thin bodies

It is shown that, in accordance with the law of plane sections representing the basis of the theory of thin bodies, two analogies are true: a nonstationary analogy and a stationary one. Within the framework of the stationary analogy, a new-type expansion reducing a three-dimensional problem to a stationary two-dimensional one is introduced. The asymptotic conditions of validity of the stationary and nonstationary analogies were determined and the boundary-layer conceptions for both cases were compared. Solutions of the internal and external problems on a two-dimensional flow in a narrow zone were obtained in the closed form. An asymptotically correct mathematical model of a flow in a film is proposed. The stationary and nonstationary analogies for a swirling flow around a body and a flow around a rotating body were determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 45–54, September–October, 2007.     

Theory of the thin film transistor

A theoretical model for a polycrystalline film is proposed which takes account of the potential barriers at the intergrain boundaries and the band bending at the semiconductor/insulator interface. It is shown that a thin film transistor equation based on this model gives an improved fit with experiment compared with a model assuming no band bending at the interface. It is concluded that the device performance is dominated by the semiconductor/insulator interface.     

On the tearing of thin sheets

We perform an experimental study to investigate the propagation of one or two cracks in a thin elastic sheet of a brittle material torn in an out-of-plane shear mode. We observe that a single crack always follows a straight path, whereas two cracks propagating simultaneously follow curved paths and merge, forming a tongue-like shape. The present experimental setup allows the understanding of how the energy introduced at a large scale is focused at the crack tip. We find that the geometry of the sheet is determined by the direction of a large scale force, applied to the crack tip, which is perpendicular to cracked surfaces. While the material is deformed at large scales under mode III loading, the geometry of system in the vicinity of the crack tip adapts such that the material is locally broken under a pure mode I loading.     

Effects of the integrity of silicon thin films on the electrical characteristics of thin dielectric ONO film

Capacitors with two kinds of lower electrodes were fabricated and their effects evaluated on the electrical characteristics of oxide–nitride–oxide (ONO) film. One of the electrodes was made of amorphous silicon film chemically deposited using a gas mixture of Si2H6–PH3; the other was made of poly-Si film deposited by SiH4 decomposition and doped by As+ ion implantation. The ONO thin dielectric layer was composed of natural oxide, CVD silicon nitride and thermal oxide formed on the silicon nitride. The capacitance, the leakage current, the dielectric breakdown field and the time-dependent dielectric breakdown (TDDB) were tested to evaluate the electrical properties of the capacitors. The leakage current and the dielectric breakdown voltage showed similar values between the two capacitors, whereas the TDDB under negative bias showed a great difference. This indicates that, with respect to electrical properties, the integrity of the oxide grown on the in situ P-doped amorphous silicon is better than the oxide grown on the As+ ion-implanted poly-Si. What is more, phosphorus in the amorphous silicon did not lead to any problems with junction depth, even after post heat treatment at 950°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Electrical conductivity in thin and very thin platinum films

The two-photon transition probability between electron energy bands in a semiconductor film is discussed, taking quantum size effects into account. An expression for the absorption rate of one of the two photons is given as a function of the frequency corresponding to all the types of critical points. The anisotropy of non-cubic materials is taken into account. The numerical calculation of the absorption coefficient is performed for the case of ZnS near the extremal point.     

Impulse in the piercing of thin plates

Institute of Strength Problems, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Problemy Prochnosti, No. 10, pp. 95–98, October, 1988.     

Electromagnetic approach to the thin element approximation

Abstract

We show that the rigorous Fourier modal method yields the thin element approximation when the feature sizes and the period tend to infinity. The transversal eigenmodes of the structure can be divided into sets whose effective refractive index corresponds to the refractive indices of the grating. Each set can be treated as the thin element approximation with constant amplitude and piecewise continuous phase transmission. We also demonstrate that the primary reason for the rapid failure of the thin element approximation with thick binary structures is attributable to destructive interference of the waveguide modes.