自由体积理论在离子注入聚对苯膜导电机理研究中的应用

采用离子注入掺杂技术 ,研究了聚对苯 (PPP)薄膜的离子束效应。当 2 0～ 70 ke V的 Ar+和 N+注入后 ,聚对苯薄膜的电导率随着剂量的增加而迅速增加。当剂量为 1× 10 1 7ions/cm2时 ,电阻率下降 7个数量级。FT- IR光谱图显示了 Ar+注入使聚对苯分子链部分 C- C和 C- H的 σ键断裂 ,从而改善了它的导电性能。通过超高阻测试仪研究了聚对苯薄膜表面电导率与温度的关系 ,从高分子自由体积理论的角度对离子注入聚对苯薄膜离子注入导电机理进行了研究。     

离子注入聚(2-甲氧基-5-辛氧基)对苯乙炔薄膜的改性研究

采用能量为 ( 10～ 35 )keV ,剂量为 ( 3 0× 10 15～ 4 8× 10 17)ions/cm2 的氮离子 (N+)对聚 ( 2 甲氧基 5 辛氧基 )对苯乙炔 (PMOCOPV)进行离子注入改性。PMOCOPV薄膜的电导率随注入离子能量和剂量的增加而迅速提高。当注入N+的能量为35keV ,剂量为 4 8× 10 17ions/cm2 时 ,PMOCOPV薄膜的电导率为 0 0 96S/cm ,比本征态的电导率提高了 7个数量级。通过超高阻测试仪研究了PMOCOPV薄膜表面电导率与温度的关系 ,发现N+注入PMOCOPV薄膜的电导活化能为 0 15 6eV。离子注入PMOCOPV薄膜的电导率的环境稳定性优于I2 和FeCl3 掺杂的PMOCOPV。对离子注入PMOCOPV薄膜的导电机理进行了初步探讨。     

聚(2,5-二丁氧基)对苯乙炔的制备及其离子注入改性研究

通过双醚化反应、氯甲基化反应以及在强碱性条件下进行的脱氯化氢反应,制备出新型光电功能材料聚(2,5 二丁氧基)对苯乙炔(PDBOPV)。采用能量为10～35keV,剂量为3.0×1015～4.8×1017ions/cm2的氮离子(N+)对PDBOPV进行离子注入改性。PDBOPV薄膜的电导率随注入离子能量和剂量的增加而提高。当注入N+的能量为35keV,剂量为4.8×1017ions/cm2时,PDBOPV薄膜的电导率为0.136S/cm,比本征态的电导率提高了8个数量级。通过超高阻测试仪研究了PDBOPV薄膜表面电导率与温度的关系,发现N+注入PDBOPV薄膜的电导活化能为0.155eV。离子注入PDBOPV薄膜的电导率的环境稳定性能优于Br2、I2和FeCl3掺杂的PDBOPV。对离子注入PDBOPV薄膜的导电机理进行了初步探讨。     

电子束蒸发a-Si:Co薄膜的离子注入改性研究

用电子束蒸发技术制备非晶硅薄膜,不同剂量Co离子注入后真空退火改性.X射线衍射法分析了样品的物相变化特征,发现Co离子注入可诱导非晶硅结晶,有一优化注入剂量5×1016ions/cm-2,使晶化Si(111)峰最强.还测量了非晶硅薄膜电阻率,揭示薄膜电阻温度系数随Co离子掺杂浓度和退火温度改变的规律;在退火温度500℃,离子注入量5×1015ions/cm-2条件下,获得TCR系数高达-2.5%的薄膜材料.     

电子束蒸发a-Si∶Co薄膜的离子注入改性研究

用电子束蒸发技术制备非晶硅薄膜,不同剂量Co离子注入后真空退火改性。X射线衍射法分析了样品的物相变化特征,发现Co离子注入可诱导非晶硅结晶,有一优化注入剂量5×1016ions/cm-2,使晶化Si(111)峰最强。还测量了非晶硅薄膜电阻率,揭示薄膜电阻温度系数随Co离子掺杂浓度和退火温度改变的规律;在退火温度500℃,离子注入量5×1015ions/cm-2条件下,获得TCR系数高达-2.5%的薄膜材料。     

C离子注入对SiO2薄膜光致发光特性的影响

先用湿氧化法在单晶硅表面生长了非晶态SiO2薄膜,再用不同能量的C离子对薄膜进行注入,然后用荧光光谱分析了注入参数(注入能量、剂量)与发光特性改变的关联。研究发现,C离子注入能显著影响薄膜的发光特性,并且薄膜发光特性的改变强烈依赖于C离子的注入能量和注入剂量。对C离子注入SiO2薄膜引起发光特性改变的可能机理进行了简单讨论。     

PET基纳米Ag薄膜导电性能及AFM分析

为了研究在PET基非织造布上沉积纳米Ag薄膜厚度对薄膜表面形貌及导电性能的影响，采用磁控溅射法，在PET非织造布上制备了不同厚度的纳米结构Ag薄膜，采用原子力显微镜（AFM）分析不同厚度纳米结构Ag薄膜形貌及粒径的变化；研究了纳米Ag薄膜厚度与薄膜导电性能的关系。实验结果表明：随着膜厚的增加，膜表面逐渐形成连续结构；同时PET非织造布基银薄膜存在一个临界膜厚，在临界膜厚处，薄膜致密度更高，生长更为均匀，薄膜缺陷较少；同时，随着膜厚增加，导电性能提高，在临界膜厚处，电阻率达到最小。     

离子注入薄膜电阻与剂量关系计算的基本模型

离子注入薄膜的电阻随离子注入的剂量而变化,本文以一个基本模型对此进行讨论。模型由薄膜厚度效果、注入离子对传导电子的散射及辐照损伤三因素组成。模型能较好地说明实验曲线。尤其在200keV Ar~+离子注入Cu膜的实验中,发现辐照损伤对电阻变化有着重大影响。     

低能离子注入对聚吡咯甲烯的改性

利用低能氮离子对聚[(3乙酰基吡咯-2,5-二)对二甲氨基苯甲烯](Papdmabeq)薄膜进行了离子注入改性(注入能量为10～35 keV、剂量为1.2×1016～2.2×1017ions/cm2),研究了与材料三阶非线性极化率相关的物理量的变化规律.结果表明,氮离子注入使Papdmabeq薄膜的光电特性都发生了显著变化.适当能量和剂量的氮离子注入Papdmabeq薄膜后,薄膜中导电岛的数量增加,在聚合物分子链间形成了大的导电区域,导致其电导率显著提高.当注入离子的能量为25 keV、剂量为2.2×1017ionS/cm2时,Papdmabeq薄膜的电导率为9.2×10-4S/cm,比本征态Papdmabeq的电导率提高了5个数量级,且离子注入后薄膜电导率的环境稳定性优于经碘掺杂的Papdmabeq.氮离子注入可以使这种聚合物薄膜在可见光范围内的光吸收大幅度提高,使共轭程度得到显著增强.当注入离子的能量为35 keV、剂量为2.2×1017ions/cm2时,Papdmabeq的光学禁带宽度(Eg)由1.626 eV降低到1.340 eV.     

N离子注入对TiN薄膜的组织及性能的影响

对钛合金基体上的TiN薄膜进行了不同剂量N离子的注入。利用扫描电镜、X射线衍射对离子注入前后组织进行了分析,并进行了硬度、摩擦磨损实验。结果表明:N离子注入使膜层呈现非晶化趋势,并随剂量增大而增强,当剂量为1.2×10~(18)ions/cm~2时膜层非晶化,晶粒得到了细化;当剂量为9×10~(17)ions/cm~2时变化最明显,尺寸约为20 nm以下;表面硬度得到提高,其增幅受到剂量及晶粒细化影响,最大增幅约为163.8 HV;摩擦磨损性能在TiN膜层表面硬度提高、粗糙度降低及长程效应的影响下也得到了较大提高,主要受注入剂量影响。     

高速钢基体离子注氮对c-BN薄膜制备的影响研究

采用射频磁控溅射法在离子注氮的高速钢基体上沉积制备c-BN薄膜,主要研究离子注氮层对c-BN薄膜相结构和内应力的影响;采用各种现代分析方法对沉积的薄膜进行了表征分析,包括傅立叶红外光谱(FTIR)、X射线光电子能谱(XPS)和原子力显微镜(AFM)等分析方法;试验结果表明:高速钢基体上离子注氮有利于立方氮化硼含量的提高和薄膜内应力的降低,同时注氮处理的高速钢基体上沉积的薄膜表面形貌平整,结晶性较好.并采用X射线衍射分析(XRD)对高速钢基体的离子注氮层进行了相结构分析,探索研究了离子注氮层对c-BN薄膜生长的影响.     

Ion-beam modifications of the surface morphology and conductivity in some polymer thin films

Studies on the surface micromorphology and surface conductivity in thin polymer films of poly vinyl alcohol (PVA) and poly ethylene oxide (PEO) in both as-grown and ion-implanted polymer films have been carried out to reveal certain specific features of the ordered state in these materials. Optical microscopic investigations revealed the existence and enhanced formation in number of spherulites and dendrites in ion-implanted films relative to the as-grown films. The number and rate of formation of spherulites indicated an increase in the degree of crystallinity in these films. Measurements of surface conductivity of as-grown and ion-implanted polymer films, employing four-point probe method, indicated a decrease in electrical conductivity on ion-implantation. Photomicrographic analysis of the PVA and PEO thin film surfaces, has enabled to propose a temperature-stress induced mechanism of crystallization in conjunction with the surface conductivity measurements. The decrease in surface conductivity on ion-implantation in both PVA and PEO thin films, is attributed to a decrease in mobility of macromolecular charged species due to an increase in degree of crystallinity as has been observed by optical microscopy.     

Electrical properties optimization of silver nanowires supported on polyethylene terephthalate

ABSTRACT

The aim of this study is the enhancement of the electrical properties of thin films obtained from silver nanowires (AgNWs) deposited on a flexible polyethylene terephthalate (PET) support. First, AgNWs were obtained by the “polyol” liquid phase synthesis method in the presence of chloride ions. After purification, the AgNWs were successively deposited on a flexible support of PET by doctor blade method. To improve the adhesion of the AgNWs coating to the substrate, thin films of polymethyl methacrylate (PMMA) were interposed between the layer of AgNWs and PET substrate. The properties of the thin films have been studied depending on the number of AgNWs layers and heat treatment procedure. Characterization of pure AgNWs as well as of AgNWs/PMMA/PET structures has been carried out by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray analysis, transmission electron microscopy, UV–Vis spectroscopy, and scanning probe microscopy. The sheet resistance of the transparent conducting films was determined by four point probe measurement. Best results in terms of homogenous conductance across the film and optical transmittance have been obtained for samples prepared by deposition of four successive layers of AgNWs. Further heat treatment improved the conductivity of AgNWs on the PMMA/PET substrate. For these films, the sheet resistance decreased from 41.25 to 29.55 Ω/sq after 40 min of heat treatment in air at 150°C.     

Uniaxial and cubic anisotropy constants in ion-implanted Sm,Tm,Ga:YIG bubble thin films

The effects of ion implantation into (SmTmY)3(GaFe)5O12garnet thin films have been studied by ferromagnetic resonance. He+ ions were used for implantation with doses ranging from 3 to 4 × 10¹⁵He+/ cm²and implantation energy ranging from 150 to 175 Kev. The uniaxial and cubic anisotropy constants have been studied as a function of temperature from 0°C to 100°C for both as-grown and ion-implanted films. The implantation has effectively changed an easy-axis anisotropy to that of an easy plane in the implanted layers of the films. A cubic anisotropy constant K1with values varying from 4 × 10³to 6 × 10³erg/cm³at room temperature has been observed in these films. The results also indicated that to the first order, the implanted region in the film was essentially magnetically uncoupled from the bulk of the film.     

Pretreatment of polyethylene terephthalate substrate for the growth of Ga-doped ZnO thin film

The effect of the pretreatment of polyethylene terephthalate (PET) substrate on the growth of transparent conducting Ga-doped ZnO (GZO) thin film was investigated. Because of its high gas and moisture absorption and easy gas permeation, PET substrate was annealed at 100 degrees C in a vacuum chamber prior to the sputtering growth of GZO thin film for the outgassing of impurity gases. GZO thin film was deposited on the pretreated PET substrate by rf-magnetron sputtering and significantly improved electrical properties of GZO thin film was achieved. Electrical and structural characterizations of the GZO thin films were carried out by 4-point probe, Hall measurement, and scanning electron microscopy, and the effects of the pretreatment on the improved properties of GZO thin films were discussed. This result is not only useful to PET substrate, but also could be applicable to other plastic substrates which inevitably containing the moisture and impurity gases.     

FeS2/TiO2复合薄膜光电性能

采用溶液浸渍法在ITO导电玻璃表面的多孔TiO2薄膜上沉积了FeS2薄膜.使用Fe2O3粉末保护裸露在外的ITO导电膜在硫气氛中热处理后,制得了FeS2/TiO2复合薄膜.应用B531/H数显测厚指示表、数字式四探针测试仪、XJCM-8太阳电池测试仪等研究了FeS2/TiO2复合薄膜的厚度、ITO导电玻璃的电阻率以及FeS2/TiO2复合薄膜的光电性能.结果表明：此方法制得的FeS2/TiO2复合薄膜具有良好的光电性能;且ITO导电膜的电阻率变化较小.因而适宜制备色素增感太阳能电池（DSSC）.     

Oxide rate characterization of high dose krypton- implanted silicon

A technique for removing thin silicon layers by anodization was used in an investigation of the depth profiles of heavily disordered regions in silicon which had undergone krypton ion implantation. The method is based on the fact that the oxidation rate of high dose ion-implanted silicon depends strongly on the concentration of easy paths with a high oxygen conductivity. It is speculated that the highly damaged regions in implanted silicon are new phase regions resulting from dopant precipitation. Because of their different chemical and physical properties from those of silicon, the new phase regions after transformation into oxide may act as easy paths for oxygen atoms migrating during anodization. A set of profiles produced by implanting krypton ions of energy 10–300 keV to a total dose of (1–2) × 10¹⁷ ions cm^-2 was obtained and was analysed by the method of moments. The average range, straggling, skewness and kurtosis of the measured profiles were compared with theoretical results for ion and damage distributions calculated using the method of Winterbon.     

New chemical methods for the deposition of Cu1·8S and TlSe thin film

New chemical methods for the deposition of thin film of Cu_1·8S and TlSe have been developed. The deposition of Cu_1·8S thin film has been performed by thiourea, ammonia and Cu²⁺ ions at room temperature, while TlSe thin films are obtained from triethanolamine as complexing agent, ammonia, sodium selenosulphate solution and Tl¹⁺ ions at room temperature. The electrical resistance, mobility, carrier concentration and optical band gap have been measured.     

Processing and performance of organic insulators as a gate layer in organic thin film transistors fabricated on polyethylene terephthalate substrate

Fabrication of organic thin film transistor (OTFT) on flexible substrates is a challenge, because of its low softening temperature, high roughness and flexible nature. Although several organic dielectrics have been used as gate insulator, it is difficult to choose one in absence of a comparative study covering processing of dielectric layer on polyethylene terephthalate (PET), characterization of dielectric property, pentacene film morphology and OTFT characterization. Here, we present the processing and performance of three organic dielectrics, poly(4-vinylphenol) (PVPh), polyvinyl alcohol (PVA) and poly(methyl methacrylate) (PMMA), as a gate layer in pentacene-based organic thin film transistor on PET substrate. We have used thermogravimetric analysis of organic dielectric solution to determine annealing temperature for spin-coated films of these dielectrics. Comparison of the leakage currents for the three dielectrics shows PVA exhibiting lowest leakage (in the voltage range of ?30 to +30 V). This is partly because solvent is completely eliminated in the case of PVA as observed by differential thermogravimetric analysis (DTGA). We propose that DTGA can be a useful tool to optimize processing of dielectric layers. From organic thin film transistor point of view, crystal structure, morphology and surface roughness of pentacene film on all the dielectric layers were studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). We observe pyramidal pentacene on PVPh whereas commonly observed dendritic pentacene on PMMA and PVA surface. Pentacene morphology development is discussed in terms of surface roughness, surface energy and molecular nature of the dielectric layer.     

导电聚合物MEH-PPV表面光电特性的研究

用接触电位差(CPD)方法研究了导电聚合物MEH-PPV薄膜的光电特性，测得MEH-PPV的能隙为2．1eV，表面功函数为4．7-4．8eV，是p型导电材料，同时研究了不同铸膜溶剂对薄膜光电特性的影响，测得由不含芳环的四氢呋喃为溶剂制得的薄膜表面功函数比由含芳环的氯苯为溶剂制得的薄膜低0．15eV。