LB法制备的P(VDF-TrFE)共聚物薄膜其光学和电学特性研究

运用郎缪尔-布尔吉特法在聚酰亚胺衬底上制备聚偏氟乙烯及三氟乙烯(P(VDF-TrFE))共聚物薄膜.不同厚度薄膜的X射线衍射结果表明,薄膜具有良好的结晶特性,取向为(110).运用波长范围为300～1300nm的椭圆偏振光谱仪对薄膜光学特性进行了表征;运用Cauchy模型对不同角度(θ=75°和85°)测得的Ψ和Δ数据进行了拟合.获得了P(VDF-TrFE)薄膜的光学参数n, k, α以及薄膜的厚度.另外对薄膜的铁电性质的测量,其剩余极化达到了6.3μC/cm2, 矫顽电场为100MV/cm.介电测量得到了薄膜两个明显的相变,铁电-介电相变以及β弛豫.     

P(VDF/TrFE)热释电探测器的研究

采用电晕极化和超低频电场极化两种方法极化偏氟乙烯/三氟乙烯共聚物P(VDF/TrFE)73/27,发现制得的热释电探测器性能相似.计算了P(VDF/TrFE)73/27热释电探测器的介质损耗噪声,发现计算值与探测器噪声测量值符合得很好,从而得出P(VDF/TrFE)73/27热释电探测器噪声主要来源于P(VDF/TrFE)73/27介质损耗噪声.     

近场静电纺丝制备P(VDF TrFE)压电纤维

采用近场静电纺丝法制备了P（VDF TrFE）（聚偏氟乙烯PVDF和三氟乙烯TrFE的共聚物）压电纤维,研究了不同的电纺工艺参数对纤维直径和形貌的影响。结果表明,近场静电纺丝法的工艺参数对纤维形貌特征有决定性影响。其中,P（VDF TrFE）电纺溶液的质量浓度对纤维的形成起决定性因素,当P（VDF TrFE）电纺溶液质量比小于12%时,液滴下落过程中溶液中的溶剂挥发速度不够,导致电纺工作时溶液沉积到衬底前无法呈纤维状;在合适的驱动电压范围内,施加的电压越大,纤维直径越细;同样,采集器的移动速度越快,纤维的直径越细;电纺获得的P（VDF TrFE）纤维直径可达（0.7~12） μm。此外,根据P（VDF TrFE）自身的压电特性,给以纤维一定的弯曲形变,测试了电纺丝法制备的P（VDF TrFE）纤维是否产生极化。实验结果表明,原位制备的纤维未能表现出明显的压电性。     

(100)定向CVD金刚石薄膜的制备及其电学性能

采用HFCVD制备金刚石薄膜的方法,以乙醇为碳源，氢气为载气，在适当的衬底温度下，合成出具有(100)晶面取向均匀生长的金刚石薄膜．SEM，XRD和Raman分析表明,所合成的金刚石薄膜是高质量的多晶(100)取向膜，厚度均匀、化学性能稳定,结构和性能与天然金刚石相接近．研究了室温下(100)取向金刚石薄膜的暗电流电压特性、稳态55Fe 5.9keV X射线辐照下的响应和电容频率特性．结果表明，退火后(100)取向多晶金刚石薄膜具有较低的暗电流和较高的X射线响应；高频下，电容和介电损耗都很小且趋于稳定，不随频率的变化而变化．     

(100)定向CVD金刚石薄膜的制备及其电学性能

采用HFCVD制备金刚石薄膜的方法,以乙醇为碳源,氢气为载气,在适当的衬底温度下,合成出具有(100)晶面取向均匀生长的金刚石薄膜.SEM,XRD和Raman分析表明,所合成的金刚石薄膜是高质量的多晶(100)取向膜,厚度均匀、化学性能稳定,结构和性能与天然金刚石相接近.研究了室温下(100)取向金刚石薄膜的暗电流-电压特性、稳态55Fe 5.9keV X射线辐照下的响应和电容-频率特性.结果表明,退火后(100)取向多晶金刚石薄膜具有较低的暗电流和较高的X射线响应;高频下,电容和介电损耗都很小且趋于稳定,不随频率的变化而变化.     

P(VDF/TrFE)聚合物薄膜光波导的实验研究

采用棱镜耦合法和偏振反射技术研究了Ｐ（ＶＤＦ／ＴｒＦＥ）聚合物薄膜光波导特性。配制适当重量比浓度的Ｐ（ＶＤＦ／ＴｒＦＥ）溶液,通过提高极化时的温度,可制成均匀透明的极化聚合物薄膜平面波导。Ｐ（ＶＤＦ／ＴｒＦＥ）成膜后薄膜内部的晶界与晶粒对于其光学性质的影响可以获得较大改善。样品用旋涂法制备。研究了制备工艺对光学特性的影响。     

MIC多晶硅薄膜的光学与电学特性及其优化

制备了4种P型掺杂的多晶硅薄膜;固相品化(SPC)、金属诱导(MIC)、准分子激光晶化(ELA)和低压化学气象沉积(LPCVD)多晶硅薄膜,并且研究了它们的光学特性与电学特性.结果发现,MIC多品硅薄膜具有最小的可见光吸收率;ELA和MIC有较小的方块电阻,而SPC和LPCVD方块电阻较大.最后通过对MIC多晶硅薄膜厚度的优化表明,厚度为40 nm的MIC多晶硅薄膜最适合做有机电致发光器件的像素电极.     

sol-gel 法制备ATO薄膜的结构与光学性能研究

采用sol-gel法在玻璃衬底上制备ATO(SnO2∶Sb)薄膜,并用XRD、SEM、紫外-可见光谱和光致发光对薄膜进行了表征,研究了ATO薄膜的结构和光学性能。结果表明:ATO薄膜微晶晶相与SnO2一致,仍然是四方金红石结构;ATO薄膜在可见光区的透过率超过80%,当r(Sb∶Sn)为0.15时,ATO薄膜的透过率最高达87%;ATO薄膜在344～380nm处有一个很强的紫外-紫光发射带,随着Sb掺杂量的增加,发射峰逐渐变强,在r(Sb∶Sn)为0.25时,发射峰相对强度达302.4。     

sol-gel法制备ZAO薄膜的结构与光学性能研究

采用溶胶—凝胶法在普通玻璃衬底上制备了ZAO(ZnO:A1)薄膜,利用XRD、SEM、紫外—可见光谱和光致发光光谱对所制备的AZO薄膜进行了表征,研究了ZAO薄膜的结构和光学性能.结果表明:ZAO薄膜的微晶晶相与ZnO一致,且具有c轴择优取向;ZAO薄膜在可见光区的透过率超过了88％,在350～575 nm范围内有强的...     

碲化铅薄膜电学特性的研究

用真空蒸镀法制备了Pb49Te51薄膜,并对薄膜的显微结构、导电类型和电阻率等电学特性及热处理对薄膜性能的影响进行了研究。结果表明:热处理对薄膜结构和性能影响很大,热处理后薄膜呈铜黄色,晶粒有明显取向,其形状为片状,且晶粒尺寸变大为300~400nm;薄膜为p型半导体薄膜,其电阻率4.624×10–2Ω.cm比晶体材料12.410×10–2Ω.cm大。     

（英）界面极化层引起P(VDF-TrFE)电容器的电容-电压的不对称

通过研究Au/P(VDF-TrFE)/Al 电容器的变温(200 K 到310 K)电容-电压曲线,室温下观察到两个极化方向下的电容不对称,这个现象可以应用于非挥发性存储器.电容不对称程度随着温度的降低而变小,当温度低于230 K,电容不对称现象消失.P(VDF-TrFE)与Al电极之间的界面极化层可以解释观察到的电容不对称现象.     

Optical and electrical properties of crystalline indium tin oxide thin film deposited by vacuum evaporation technique

Indium tin oxide (ITO) thin film was deposited on glass substrate by means of vacuum evaporation technique and annealed at 200 °C, 300 °C and 400 °C in air for 1 h. The characterization and properties of the deposited film samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-VIS-NIR spectroscopy techniques. From the XRD patterns, it was found that the deposited thin film was of crystalline at an annealing temperature of 400 °C. The crystalline phase was indexed as cubic structure with lattice constant and crystallite size of 0.511 nm and 40 nm, respectively. The SEM images showed that the films exhibited uniform surface morphology with well-defined spherical grains. The optical transmittance of ITO thin film annealed at 400 °C was improved from 44% to 84% in the wavelength range from 250 nm to 2 100 nm and an optical band gap was measured as 3.86 eV. Hall effect measurement was used to measure the resistivity and conductivity of the prepared film.     

Low-voltage organic ferroelectric field effect transistors using Langmuir–Schaefer films of poly(vinylidene fluoride-trifluororethylene)

Langmuir–Schaefer transfer was used to fabricate ultrathin films of ferroelectric copolymer, poly(vinylidene fluoride-trifluoroethylene) (70–30 mol%), for non-volatile memory application at low operating voltage. Increasing the number of transferred monolayers up to 10 led to improved film crystallinity in the “in-plane” direction, which reduced surface roughness of the semicrystalline film. Treatment of the substrate surface by plasma results in different film coverage which was subsequently found to be governed by interaction of the deposited film and surface condition. Localized ferroelectric switching was substantially attained using piezo-force tip at 10 V on 10-monolayer films. Integrating this film as a dielectric layer into organic capacitor and field effect transistor yields a reasonably good leakage current (<10^?7 A/cm²) with hysteresis in capacitance and drain current with ON/OFF ratio of 10³ for organic ferroelectric memory application at significantly reduced operating voltage of |15| V.     

利用噪声谱表征二氧化钒薄膜的光学相变特性

利用自主搭建的实验系统,同步实时地测量了热致相变材料二氧化钒(VO2)薄膜在相变过程中的反射率及其涨落(噪声谱).实时傅里叶变换采集卡测得的噪声谱不仅可以像反射率测量一样给出样品的相变温度(55℃),还在样品的高温区金属相里发现了一个明显的噪声峰(位于15~20 MHz),而低温区半导体相的噪声谱几乎是平坦的.这种噪声峰也反映了薄膜样品中低温半导体相和高温金属相的晶体结构差异.噪声谱测量可以广泛地应用于相变材料的研究.     

基于PVDF的柔性压力传感器阵列的制备及仿真研究

采用湿法刻蚀制备了基于PVDF薄膜的柔性4×4压力传感器阵列,该传感器具有16个毫米尺寸的电容器单元。使用光学显微镜、原子力显微镜观测了传感器表面形貌,显示电极阵列的界面清晰,PVDF薄膜表面形貌平整。力电耦合效应测试的结果显示传感器的应力输入和电压输出具备高的信噪比和良好的线性关系,力电响应为12×10–3 V/kPa。受力-空载响应输出显示,对传感器施加20~80 kPa范围的脉冲压力,得到了输出0.26~0.98 V的电压信号,并且放电时间少于2.5 ms。结合仿真计算研究了传感器阵列之间的电势信号影响,结果表明相邻阵列单元间的信号干扰随着阵列所受压力增加而增加并且呈现线性关系,干扰信号为0.028×10~(–3) V/kPa,在1.4 mm~2尺寸时,低于178 kPa压力所产生的干扰信号可以近似忽略。     

不同方法及衬底类型对CdS多晶薄膜性能的影响

采用化学水浴法和磁控溅射法分别在AZO、FTO、ITO透明导电玻璃衬底上制备了CdS薄膜,利用扫描电镜、XRD以及透射光谱等测试手段,研究了两种制备方法对不同衬底生长CdS薄膜形貌、结构和光学性能的影响.研究结果表明,不同方法制备的CdS薄膜表面形貌均依赖于衬底的类型,水浴法制备的CdS薄膜晶粒度较大,表面相对粗糙.不同方法制备的CdS薄膜均为立方相和六角相的混相结构,溅射法制备的多晶薄膜衍射峰清晰、尖锐,结晶性较好.水浴法制备的CdS薄膜透过率整体低于溅射法,但在短波处优势明显.     

高强度激光对光学薄膜的破坏

在薄膜破坏中起主要作用的是个别的脉冲尖峰。分析了薄膜结构对薄膜受破坏的影响,以及SiO_2保护膜在提高ZrO_2/SiO_2膜的抗激光强度中的作用。     

TiO_2(Ag)纳米半导体薄膜的制备及其光催化性能

对热解Ｔｉ（ＯＣ４Ｈ９）４＋ＡｇＮＯ３溶胶制备的ＴｉＯ２（Ａｇ）纳米半导体薄膜光催化特性与其结构的关系进行了研究。薄膜对二卡基砜的光催化降解结果表明,热解温度显著影响薄膜的光催化作用,这与ＴｉＯ２微粒的长大和晶相转变有关;适量的Ａｇ作活性剂可以显著改善薄膜的光催化性能。     

Patterning effects on poly (3-hexylthiophene) organic thin film transistors using photolithographic processes

We explore the effects of conventional photo lithographic patterning of the active layer of poly (3-hexylthiophene) (P3HT) organic thin film transistors (OTFT) on device performance. The performance of the devices was monitored in each step of the patterning process. We successfully developed a patterning process which is compatible with plastic substrates and P3HT as the organic semiconductor. In this process, parylene and atomic layer deposition (ALD) Al₂O₃ were used as capping layers. Al₂O₃ and parylene/P3HT were etched using Al etchant and O₂ plasma reactive ion etching (RIE), respectively. The degradation occurred primarily during the ALD Al₂O₃ deposition and capping layer etching. There was a 30% degradation in mobility, a 1–2× reduction in drive current, and an increase in threshold voltage after the ALD Al₂O₃ deposition. In the capping layer etching, a near 50% degradation in mobility was observed. The patterned devices have a mobility of 0.02 cm²/V s, which is 1000× better than photo lithographically patterned P3HT OTFTs previously reported in the literature, and comparable to un-patterned P3HT devices.     

Microscopic characterization of polarization fatigue in ferroelectric vinylidene fluoride and trifluoroethylene copolymer films

Recently studies on electric fatigue in ferroelectric polymers have drawn much attention due to the potential application of ferroelectric polymers in nonvolatile memory devices. Compared to inorganic ferroelectrics, ferroelectric polymers are mostly semi-crystalline with a coexistence of crystalline phase and amorphous phase. To well understand electric fatigue in ferroelectric polymers, it is necessary to determine the different contributions from crystallites, amorphous phase and even boundaries between crystallites to polarization fatigue. Here we introduce a SPM-based technique to characterize electric fatigue in nanometer scale. Microscopic fatigue is determined by the attenuation of voltage-excited local vibration amplitudes at two kinds of local structures (the crystallites and the boundaries between crystallites), and, for comparison, macroscopic electric fatigue characteristics are also recorded by a standard Sawyer–Tower circuit. Our observations indicate that the attenuation rate of vibration amplitude on crystallites is much slower than that at boundaries. Abnormal increase of vibration amplitude and slim local butterfly loops are observed at some of boundaries in deeply fatigued films.