InP上Al膜的阳极氧化及其特性研究

本文报道了半导体InP上Al膜阳极氧化的研究,并用AES,V-V,DLTS和椭圆仪等测试方法研究了氧化膜的稳定性、电学特性、组分的纵向分布以及Al_2O_3/InP的界面特性,研究结果表明,阳极氧化Al_2O_3的介电常数为11～12,Al_2O_3/InP界面存在一个能量上连续分布的电子陷阱,DLTS峰值对应的能级位置约在E_c-E_c=0.5eV,其俘获截面约为10~(-15)cm~2,Al_2O_3/InP的界面态密度为10~(11)cm~(-2)eV~(-1)。阳极氧化Al_2O_3的稳定性要比InP自身氧化物好得多,更适于用作器件的钝化保护和扩散掩蔽膜。     

北京城市大气高含氧有机分子的定量测量 #br#

大气高含氧有机分子是二次有机气溶胶的重要前体物。使用气态硫酸分子作为大气高含氧有机分子的替代 物评估其在硝酸根-大气常压界面化学电离飞行时间质谱离子化过程中的电离效率, 并基于高分辨率差分电迁移率粒 径谱仪串联飞行时间质谱建立了质谱传输效率的矫正方法, 从而建立了大气高含氧有机分子的半定量方法。在此基 础上开展了北京冬季大气高含氧有机分子的外场观测, 识别了约一百一十个大气高含氧有机分子, 表征了它们的浓度 变化趋势和化学组成特征。研究发现羟基自由基在大气高含氧有机分子生成过程中具有重要作用, 而氮氧化合物也 会参与其中。从挥发性分布看, 该地区冬季高含氧有机分子中归于极低挥发性有机化合物 (ELVOC) 的最多, 低挥发性 有机化合物 (LVOC) 次之, 表明该地区大气高含氧有机分子在大气颗粒物上的凝结对二次有机气溶胶的形成具有重要 贡献。     

用扫描隧道显微镜观察偶氮苯衍生物在液体/石墨界面的组装

本文主要报道了化合物4－羟基－3′－三氟甲基偶氮苯（FAzoH)的合成及利用扫描隧道显微镜（STM）对该化合物在十一醇溶剂／石墨界面的物理吸附的单分子膜进行了研究。从得到的扫描隧道显微像观察了分子级别分辨率的单分子膜中的分子排列。主要原因是由于溶质分子中含有三氟甲基集团,又氟又具有强极性,它能与含羟基的另一相邻的溶质分子形成稳定的氢键以利于用扫描隧道显微镜得到图像,所以三氟甲基的引入对单分子膜的结构有着重要的影响。     

基于P3HT/PCBM异质结界面太阳能电池的理论及实验研究

根据整数电荷转移(ICT)模型理论分析基于P3HT为给体PCBM为受体的异质结界面,认为不同等效功函数衬底和电荷传输状态产生不同D/A界面特性。采用增加P3HT缓冲层PCBM缓冲层的方法,制备不同复合层本体异质结结构光伏器件,研究活性膜内组分变化对器件开路电压和短路电流密度的影响。结果表明增加缓冲层使器件的短路电流密度明显提高,从3.96mA/cm2分别增加到4.51mA/cm2和4.70mA/cm2,但对开路电压影响不大。     

TFT-LCD器件Al电极TFT特性研究

本文对Mo/Al/Mo作为TFT-LCD器件源/漏极的TFT特性进行了研究。与单层Mo相比,存在沟道界面粗糙,I_(off)偏大问题,通过优化膜层结构,改善界面状态,得到了平整的沟道界面和良好的TFT特性。增加Bottom Mo的厚度,可以有效减少Al的渗透,防止Al-Si化合物的形成,得到界面平整的沟道;N~+刻蚀后SF6处理对特性影响不大,增加刻蚀时间可以使I_(on)和I_(off)同时降低;PVX沉积前处理气体N_2+NH_3与H_2区别不大,都可以减少沟道缺陷,而增加H_2处理时间会增强等离子的轰击作用,减少了沟道表面Al-Si化合物,但处理时间过长可能会使沟道缺陷增加;采用bottom Mo加厚,N~+刻蚀以及PVX沉积前处理等最优条件,可以得到沟道界面良好,TFT特性与单层Mo相当的TFT器件。     

两种偶氮苯化合物LB膜的光谱与非线性光学特性

两端具有推拉电子基团的偶氮化合物中的N=N双键提供了优异的电子通道,有利于产生非线性光学效应,并且推拉电子基团对偶氮化合物的非线性光学特性有较大的影响.采用紫外可见吸收和二次谐波产生(SHG)技术研究了两种推-拉"型偶氮苯分子Langmuir-Blodgett(LB)膜的光谱和二阶非线性光学特性.4-硝基-4′-氨基偶氮苯(NAA)和4-羧基-4′-氨基偶氮苯(CAA)分子在亚相表面可以形成稳定的单分子膜,并且能较好地转移到固体基板上形成LB多层膜;由于-NO2比-COOH具有更强的吸电子能力,电子在NAA分子内更容易转移,并形成较大分子偶极矩,分子具有更大的一阶超极化率.实验测得NAA和CAA的二阶非线性系数d33分别为40.8 pm/V和24.2 pm/V,一阶超极化率β分别为1.97×10-29esu和1.17×10-29esu,NAA分子的一阶超极化率约为CAA的1.7倍,实验与理论计算结果符合较好.     

用于显示的OLEDs衬底/阳极界面研究进展

有机发光二极管(OLED),由于其诸多优异的性能而广泛引用在照明、显示等多个领域.阳极/衬底之间的界面特性影响有机发光二极管器件的寿命和性能,尤其是光耦合效率.从增加层和基底图形化两个方面介绍了阳极/衬底之间界面的研究进展,使得研究者们能够详细了解近年来有机发光二极管器件阳极/衬底之间界面的研究状况.     

LiF层对ITD/Alq~3/LiF∶Al器件性能的影响

分别制备了4种有机电致发光器件(OLEDs):ITO/Alq3/Al;ITO/Alq3/LiF(1.0nm):Al;ITO/Alq3/LiF(1.5nm)∶Al;ITO/Alq3/LiF∶(2.0nm)Al。研究了LiF的引入对金属电极与发光层界面的影响以及各种不同的界面态对器件发光性能的影响。研究结果表明:适当的LiF厚度的引入不仅可以改善器件的界面特性,而且可以提高器件的发光亮度及发光效率。     

SiC MOS界面氮等离子体改性及电学特性评价

降低SiO2/SiC界面态密度是SiCMOS器件研究中的关键技术问题。采用氮等离子体处理SiO2/SiC界面,制作MOS电容后通过I-V、C-V测试进行氧化膜可靠性及界面特性评价,获得的氧化膜击穿场强约为9.96MV/cm,SiO2/SiC势垒高度2.70eV,同时在费米能级附近SiO2/SiC的界面态密度低减至2.27×1012cm-2eV。实验结果表明,氮等离子体处理SiO2/SiC界面后能有效降低界面态密度,改善MOS界面特性。     

光学测量与仪器

本文集为扫描型探测器显微镜专辑。收录的8篇论文主要涉及:自组织化单分子膜与 SPM 的新的可能性,有机/金属、有机/有机界面中的光电流增倍现象与界面圾微细结构,基于 AFM 力变换技术的有机薄膜有机分子的高分解能观察,采用压敏阻抗悬臂阵列的AFM 像观察,采用扫描型麦克斯韦应力显微镜的有机薄膜中的电气像的毫微米刻度图象,采用扫描型探针的 Si 的表面电位与 STS 的同时测定,PAH/PAA 电解质聚合物交互吸附膜的 AFM 像观察等。     

硅灰石/橡胶复合材料界面微观结构

天然硅灰石加入固相活性剂硬脂酸,经超音速气流机械力粉碎－活化,硅灰石仍呈针状或柱状结构,表面镶着呈一定规则排列的细小颗粒,系因硬脂酸一端的羧基与硅灰石发生化学反应或化学吸附。硬脂酸另一端C17烷基与天然像胶的结构十分相似,彼此间相容性较好,硅灰石在橡胶中分布较均匀,因而活性硅灰石／橡胶复合材料界面粘结较好。     

Biosourced Antioxidants for Chemical Durability Enhancement of Perfluorosulfonic Acid Membrane

The chemical durability of perfluorosulfonic acid (PFSA) membranes is a topic of growing interest to meet Department of Energy (DOE) durability targets for heavy-duty vehicle (HDV) applications. State-of-the-art membranes like Nafion, rely on the use of cerium, heteropolyacids, and other inorganic additives to increase PFSA chemical durability. A less explored avenue for the oxidative stabilization of PFSA and hydrocarbon membranes is the use of organic antioxidants. No reversible organic antioxidant has been demonstrated to date which can enhance membrane lifetime by factors comparable to cerium. Here, ellagic acid (EA) is demonstrated as a promising radical scavenger for PFSA's. It is found that the incorporation of EA enhances the chemical durability of Nafion by 160%. EA, when incorporated with cerium as an electron donorenhances Nafion durability by at least 80% compared to a membrane incorporated with just cerium in DOE-defined durability tests. EA is found to be reversible in acidic conditions like those of fuel cells and its reversibility could be further enhanced by the use of suitable co-antioxidants.     

Optimization and Analysis of Conjugated Polymer Side Chains for High‐Performance Organic Photovoltaic Cells

Optimization and analysis of conjugated polymer side chains for high‐performance organic photovoltaic cells (OPVs) reveal a critical relationship between the chemical structure of the side chains and photovoltaic properties of polymer‐based bulk heterojunction OPVs. In particular, the impact of the alkyl side chain length on the π‐bridging (thienothiophene, TT) unit is considered by designing and synthesizing a series of benzodithiophene derivatives (BDT(T)) and thieno[3,2‐b]thiophene‐π‐bridged thieno[3,4‐c]pyrrole‐4,6(5H)‐dione (ttTPD) alternating copolymers, PBDT(T)‐(R₂)ttTPD, with alkyl chains of varying length on the TT unit. Using a combination of 2D X‐ray diffraction, Raman spectroscopy, and electrical device characterization, it is elucidated in detail how these subtle changes to the chemical structure affect the molecular conformation, thin film molecular packing, blend film morphology, optoelectronic properties, and hence overall photovoltaic performance. For copolymers employing both the alkoxy or alkylthienyl‐substituted BDT motifs, it is found that octyl side chains on TT unit yield the maximum degree of molecular backbone coplanarity and result in the highest quality of molecular packing and optimized hole mobility. Inverted devices fabricated using this PBDTT‐8ttTPD: polymer/[6,6]‐phenyl‐C₇₁‐butylic acid methyl ester active layer show a maximum power conversion efficiency (PCE) of 8.7% with large area cells (0.64 cm²) maintaining a PCE of 7.5%.     

ITO表面处理对OLED性能的影响

根据实验,分析了表面处理对OLED性能的影响.对OLED的ITO阳极进行表面处理将改变ITO膜的表面化学组成及表面形态,这将直接影响ITO膜表面的功函数,从而影响ITO向有机层的空穴注入;同时还将间接影响有机层的成膜过程及其分子组织形态及ITO膜表面有机层之间的结合.     

Interface Engineering for Solid‐State Dye‐Sensitized Nanocrystalline Solar Cells: The Use of Ion‐Solvating Hole‐Transporting Polymers

The control of interfacial charge transfer is central to the design of photovoltaic devices. This charge transfer is strongly dependent upon the local chemical environment at each interface. In this paper we report a methodology for the fabrication of a novel nanostructured multicomponent film, employing a dual‐function supramolecular organic semiconductor to allow molecular‐level control of the local chemical composition at a nanostructured inorganic/organic semiconductor heterojunction. The multicomponent film comprises a lithium ion doped dual‐functional hole‐transporting material (Li⁺–DFHTM), sandwiched between a dye‐sensitized nanocrystalline TiO₂ film and a mono‐functional organic hole‐transporting material (MFHTM). The DFHTM consists of a conjugated organic semiconductor with ion supporting side chains, designed to allow both electronic and ionic charge transport properties. The Li⁺–DFHTM layers provide a new and versatile way to control the interface electrostatics, and consequently the charge transfer, at a nanostructured dye‐sensitized inorganic/organic semiconductor heterojunction.     

Influence of surface contamination on metal/metal bond contact quality

The influence of surface cleanliness of Au/Ni coated multichip materials (MCMs), Ag plated Cu lead frames, and Al bond pads on semiconductor chips on the strength of Au wire bond contacts has been investigated. A clean surface is important for good adhesion in any kind of attachment process. Investigations by means of x-ray photoelectron spectroscopy have been performed on the bond substrates to determine the chemical composition, the nature as well as the thickness of the contamination layer. The influence of contamination on bond contact quality has been examined by pull force measurements, which is an established test method in semiconductor packaging industry for evaluating the quality of wire bonds. The results clearly show that a strong correlation between the degree of contamination of the substrate and pull strength values exists. Furthermore, a contamination thickness limiting value of 4 nm for Au and Ag substrates was determined, indicating good wire bond contact quality. The effect of plasma cleaning on wire bondability of metallic and organic (MCMs) substrates has been examined by pull force measurements. These results confirm the correlation between surface contamination and the strength of wire bond contacts for Au/Ni coated MCMs and Ag plated Cu lead frames. Atomic force microscopy measurements have been performed to determine the roughness of bond surfaces, demonstrating the importance of nanoscale characterization with regard to the bonding behavior of the substrates. Finally, bonding substrates used in integrated circuit packaging are discussed with regard to their Au wire bonding behavior. The Au wire bonding process first results in a cleaning effect of the substrate to be joined and secondly enables the change of bonding energy into frictional heat giving rise to an enhanced interdiffusion at the interface.     

High‐Resolution Characterization of Pentacene/Polyaniline Interfaces in Thin‐Film Transistors

We present the first detailed report that directly correlates the reduced contact resistance in organic thin‐film transistors (TFTs) with fundamental structural and morphological characterization at the organic semiconductor/conducting polymer interface. Specifically, the pentacene grains are similar in size and continuous across the channel/electrode interface in bottom‐contact TFTs with polyaniline (PANI) electrodes. On a molecular level, the fused rings of pentacene are oriented perpendicular to the surface both in the channel and on PANI. Accordingly, the contact resistance is small in such devices. In TFTs with gold electrodes, however, the pentacene grains are different in size and are discontinuous across the channel/electrode interface. Further, the fused rings of pentacene are oriented perpendicular to the channel surface and parallel to the gold surface. Such differences across the channel/electrode interface lead to structural and electronic disorder, which manifests itself as a significantly larger contact resistance in devices with gold electrodes.     

Nanostructured Si/Organic Heterojunction Solar Cells with High Open‐Circuit Voltage via Improving Junction Quality

Nanostructured silicon (Si) can provide improved light harvest efficiencies in organic‐Si heterojunction solar cells due to its low light reflection ratio compared with planar one. However, the associated large surface/volume ratio of nanostructured Si suffers from serious surface recombination as well as poor adhesion with organics in organic‐Si heterojunction solar cells, which leads to an inferior open‐circuit voltage (V_oc). Here, we develop a simple and effective method to suppress charge recombination as well as enhancing adhesion force between nanostructured Si and organics by incorporating a silane chemical, namely 3‐glycidoxypropyltrimethoxydsilane (GOPS). GOPS can chemically graft onto nanostructured Si and improve the aqueous organic wetting properties, suppressing surface charge recombination velocity dramatically. In addition, this chemically grafted layer can enhance adhesion force between organics and Si. In such a way, a record V_oc of 640 mV associated with a power conversion efficiency of 14.1% is obtained for organic‐nanostructured Si heterojunction devices. These findings suggest a promising approach to low‐cost and simple fabrication for high‐performance organic‐Si solar cells.     

Effect of organic acids on copper chemical mechanical polishing

In chemical mechanical polishing (CMP) of Cu, organic acids are often used as additives of slurries. This paper studied the effects of citric acid, oxalic acid, glycolic acid and glycine on Cu CMP performance. Our experiments explored the difference of these organic acids in surface reactions with Cu. The results showed that organic acids could chelate the passive film of Cu, and oxalic acid would further form precipitates with copper ions to change the chemical and mechanical action during CMP. Potential-pH diagrams, electrochemical polarization and impedance analyses were used to examine the behaviors of Cu in various organic acid slurries. The results indicated that the proposed equivalent circuits from impedance analysis for Cu CMP system could provide a good index to surface roughness. Furthermore, we also discussed the effects of used organic acids on reducing particle contamination after Cu CMP by measuring the difference of isoelectric points between Cu and α-Al₂O₃. The result showed that the addition of organic acid could efficiently decrease particle contamination.     

Bonding strengths at plastic encapsulant–gold-plated copper leadframe interface

The effect of plasma treatment on the adhesion strength of a moulding compound to a leadframe is evaluated on the basis of leadframe pull-out tests. The contact angle measurement method and atomic force microscopy are employed to quantitatively characterise the modified surface so as to correlate with the bond strength measurements. Process parameters including the type of gases used and the duration exposed in air before moulding are specifically studied. The results indicate that plasma treatments of leadframe have three major ameliorating effects, namely, clean surface due to the removal of organic contaminants, enhanced chemical compatibility with moulding compound and rough surface with associated larger surface contact area for better mechanical interlocking. Exposure of plasma treated leadframes in air before moulding is found detrimental to interface bond quality, recommending moulding operations immediately after treatment. It is also shown that roughness on the nanoscale is an important surface characteristic that has a strong correlation with the interface bond strength.