Microstructural Characterization and Charge Transport in Thin Films of Conjugated Polymers

The performance of semiconducting polymers has been steadily increasing in the last 20 years. Improved control over the microstructure of these materials and a deeper understanding of how the microstructure affects charge transport are partially responsible for such trend. The development and widespread use of techniques that allow to characterize the microstructure of semiconducting polymers is therefore instrumental for the advance of these materials. This article is a review of the characterization techniques that provide information used to enhance the understanding of structure/property relationships in semiconducting polymers. In particular, the applications of optical and X‐ray spectroscopy, X‐ray diffraction, and scanning probe techniques in this context are described.     

An Inverse Approach for Extracting Elastic-plastic Properties of Thin Films from Small Scale Sharp Indentation

An inverse method for extracting the elastic-plastic properties of metallic thin films from instrumented sharp indentation has been proposed in terms of dimensional analysis and finite element modeling.A wide range of materials with different elastic modulus,yield strength,and strain-hardening exponent were examined.Similar to the Nix-Gao model for the depth dependence of hardness H,(H/H0)2=1+h*Hh,the relationship between elastic modulus E and indentation depth h can be expressed as(E/E0)4=1+h*Eh.By combining these two formulas,we find that there is a relationship between yield stress σ y and indentation depth h:σy = σy0·(1+h*Hh)f(n)·(1+h*Eh)[0.25-0.54f(n)],where σ y0 is the yield strength associated with the strainhardening exponent n,the true hardness H0 and the true elastic modulus E0.f(n)= 1/2(1-n) is constant,which is only related to n,and h*H and h*E are characteristic lengths for hardness and elastic modulus.The results obtained from inverse analysis show that the elastic-plastic properties of thin films can be uniquely extracted from the solution of this relationship when the indentation size effect has to be taken into account.     

钇改性PZT薄膜的极化印刻研究

铁电ＰＺＴ薄膜的极化印刻（ｉｍｐｒｉｎｔｉｎｇ）是ＰＺＴ不挥发存储器失效的重要原因之一．本文研究了不同钇量改性的ＰＺＴ（４０／６０）铁电薄膜在高温（１２０℃）和偏置电压下的极化印刻特性,发现适量的钇掺杂,改善了ＰＺＴ薄膜电容器单元的极化印刻．     

磁控溅射Cu-Nb和Cu-Mo薄膜结构与性能

采用磁控溅射制备含1.16%～15.8%(原子分数)Nb的Cu-Nb及含2.2%～27.8%Mo的Cu-Mo合金薄膜,井采用EDX、XRD、SEM、显微硬度仪和电阻计对薄膜的成分、结构和性能进行研究。结果表明,Nb和Mo的添加分别使Cu-Nb及Cu-Mo薄膜晶粒显著细化,Cu-Nb和Cu-Mo薄膜呈纳米晶结构,存在Nb在Cu中的fcc Cu(Nb)和Mo在Cu中的fcc Cu(Mo)非平衡亚稳过饱和固溶体,固溶度随Nb或Mo含量增加而上升。添加Nb和Mo显著提高Cu-Nb及Cu-Mo薄膜的显微硬度和电阻率,且随Nb或Mo含量增加而升高。经650℃热处理1h后,Cu-Nb和Cu-Mo薄膜显微硬度和电阻率均下降,且分析表明均发生基体相晶粒长大,并出现微米-亚微米级富Cu第二相,Cu-Nb及Cu-Mo薄膜结构和性能形成及演变的主要原因是添加的Nb、Mo引起的晶粒细化效应以及退火中基体相晶粒度的增大。     

氧化镉薄膜的制备与性质研究

本文以醋酸镉、丙醇、丙三醇、三乙胺组成的先驱体溶液作为起始物，采用溶胶-凝胶法，利用旋转涂覆技术，于玻璃基体上制备了高透过率、低电阻的氧化镉薄膜。研究了薄膜的光学性质、导电性能、表面形貌。薄膜的电阻由双探针法测定，并在热处理温度为270℃时得到了一个最低电阻，其值为58．8Ω；薄膜的透过性能由紫外-可见分光光度计测定，在可见光范围内透过率高达90％以上；薄膜的表面形貌由扫描电子显微镜(SEM)测定。研究结果表明，热处理温度对薄膜的导电和可见光透过性能有很大影响。     

铁电PLZT薄膜的钙钛矿型结构与性能的研究

讨论了用射频磁控溅射沉积的ＰＬＺＴ（７．５／６５／３５）陶瓷薄膜的结构和铁电性能。研究表明，在不加热的Ｐｔ／Ｔｉ／Ｓｉ衬底上沉积ＰＬＺＴ薄膜即钙钛矿型的高度取向薄膜，没有绿石相出现，同时具有很好的微观结构；增加薄膜的厚度导致ａ轴取向的增长；火处理有助于ＰＬＺＴ薄膜的钙钛矿相的增长并在薄膜中出现了蔷薇状共晶组织。这种ＰＬＺＴ薄膜的剩余极化强度、矫顽场强度分别为２２．９μ／ｃｍ＾２和６２．４ＫＶ／ｃｍ     

碲氧溅射薄膜的光学性质

碲氧薄膜是很有希望的可擦写光盘介质材料。本文用射频溅射技术制备碲氧系统的薄膜。测定热处理前后薄膜的光学特性(光透过率、反射率、折射指数、光吸收系数和光能隙)和 X 射线衍射特性,并研究了这些性能与靶材的组份关系,还测定了这些薄膜激光喇曼光谱,并讨论它们的结构特征。     

Transverse Magnetoresistance Behaviors of Thin Polycrystalline Bismuth Films

The magnetoresistance (MR) properties of several thin polycrystalline bismuth films have been measured over a wide temperature interval (0.42K T 292 K) and a magnetic field range (0 T B 45 T). In most cases, the magnetic field was oriented in the transverse direction, with the field parallel to the substrate of the film and also perpendicular to the current direction. These MR results are different from those in either the perpendicular or parallel field orientations. The anomalous behavior of the transverse magnetoresistance can be explained considering partially diffused scattering of the carriers at the top and bottom surfaces of the films. The data are fitted using a phenomenological model, based upon the theory of Way and Kao and also using the two carrier expressions of Pippard and Fawcett (P-F).     

Zero‐Point Correction Method for Nanoindentation Tests to Accurately Quantify Hardness and Indentation Size Effect

Abstract: An original treatment method is proposed to accurately determine by nanoindentation, the macrohardness and the indentation size effect (ISE). This method is applied to stainless steel specimens having different rough surfaces. It uses load versus indentation depth curves and is based on two main original features. The first one concerns the correction of the zero point (i.e. depth equals to 0) to minimise the scattering between experimental curves. The latter are all described by usual hardness equations and are shifted by minimising the distance from a leading curve chosen in a random way among the experimental curves. The second feature is the simultaneous treatment of all the nanoindentation curves to compute the macrohardness and evaluate the ISE. The standard deviation for the estimated macrohardness is small, which indicates the robustness of the approach. It is shown that using a single nanoindentation curve can alter macrohardness estimation because of a bad consideration of the ISE. To prevent this misinterpretation, the curves should be treated simultaneously instead of averaging results of separately treated curves. A correlation is identified between the standard deviations of both surface roughness and correction of zero point, which highlights the effect of surface roughness on the scattering of the indentation curves.