气相沉积聚合法制备聚酰亚胺绝缘薄膜及其性能研究

以联苯四酸二酐和4,4’-二氨基二苯醚为单体原料使用气相沉积聚合(VDP)法制备了聚酰亚胺(PI)绝缘膜,分析不同热亚胺化处理温度对PI薄膜绝缘性能的影响。分别使用红外光谱、俄歇能谱、扫描电镜、原子力显微镜对薄膜成分以及薄膜表面形貌进行了表征;利用超高阻微电流测试仪测试了PI复合绝缘膜漏电流和电压击穿特性。结果表明:热亚胺化300℃/1 h真空(1.0×10-2Pa)处理后的PI绝缘膜内部结构致密,当场强为8.0MV/cm时漏电流密仅为8.2×10-5A/cm2;薄膜击穿场强达到8.42MV/cm,表明PI薄膜具有良好的电学性能以及热稳定性。     

后栅结构SnO2场致发射显示器件的研制

采用高温气相法生长SnO2纳米线,扫描电子显微镜和X射线衍射仪分析表明所生长的SnO2纳米线大小均匀,直径约为150 nm,长可达10μm。结合丝网印刷法转移SnO2,制备成阴极阵列。封接阴极板与荧光屏成后栅型场致发射显示(FED)器件,测试其场致发射性能,分析讨论栅极电压和阳极电压对场发射性能的影响。实验表明后栅型SnO2-FED具有良好的栅极调控作用,在1600 V阳极电压和200 V栅极电压下工作实现全屏发光,平均发光亮度为560 cd/m2,具有潜在的应用前景。     

Ge/SiO2和Ge/ZnO/SiO2薄膜的磁控溅射制备及电学性能

采用射频磁控溅射方法以石英玻璃为衬底分别沉积制备出了Ge/SiO2和Ge/ZnO/SiO2薄膜。X射线衍射表明薄膜展示了明显的ZnO衍射峰和较弱的Ge衍射峰;傅里叶变换红外光谱曲线证明薄膜均具有各自的特征吸收峰;扫描电镜结果显示薄膜为颗粒状团簇结构,并且加入ZnO中间层可以有效的改善Ge层的质量。同时,对所得薄膜材料的电流-电压性能进行了研究,结果发现,Ge/SiO2薄膜的I-V曲线拟合后为斜线,相当于电阻;ZnO/SiO2薄膜为直线,可以认为是绝缘体;Ge/ZnO/SiO2薄膜在-10～10V之间电流电压呈线性关系,其电阻比Ge/SiO2薄膜小,当电压值超过15V之后,电流急剧增加而迅速使薄膜击穿,薄膜导通。     

阳极氧化法制备Ta2O5绝缘膜及性能研究

采用阳极氧化法在纯Ta表面制备绝缘性优良的Ta2O5介质膜,分析阳极氧化制备Ta2O5膜的基本机理,讨论不同电解液、阳极氧化电压及热处理等工艺参数对Ta2O5膜性能的影响.利用XRD、EDS和AFM分析薄膜的组织结构和表面形貌,超高阻微电流测试仪测试Ta2O5绝缘膜漏电流特性和耐击穿电压,结果表明,磷酸电解液中添加适当乙二醇溶液能有效地防止"晶化",阳极氧化电压在125～150V范围内制备Ta2O5绝缘膜耐击穿电压能力强,经350℃/60min大气气氛下热处理Ta2O5薄膜,内部结构致密,能有效提高Ta2O5绝缘膜耐击穿电压.     

Bi4Ti3O12铁电薄膜I-V特性的研究

采用溶胶-凝胶工艺(Sol-Gel)在Pt/Ti/SiO2/p-Si衬底上成功制备了低漏电流Bi4Ti3O12(BIT)铁电薄膜,对所得样品的漏导行为进行了研究.研究表明,Bi4Ti3O12薄膜的漏电流密度在+3V偏压下低于10-9A/cm2,满足器件应用的要求.在不同场强下薄膜的漏导机制不同,而且正向和负向电场作用下I-V曲线明显不同,正向漏电流明显小于负向漏电流.电压低于2V时,薄膜以欧姆导电机制为主,电压在2～5.4V(加正向电压)或2.2～3.6V(加负向电压)时,BIT薄膜应以Schottky emission导电机制为主;而对于较高的场强下,BIT薄膜以Space-charge limited currents(SCLC)导电机制为主.     

单晶Tm2O3高k栅介质漏电流输运机制研究

利用分子束外延技术在p型Si(001)衬底上外延生长了单晶Tm2O3高k栅介质薄膜,分别在不同温度下测量了薄膜的电流-电压特性。基于变温电流-电压特性数据的漏电流输运机制分析表明,单晶Tm2O3栅介质薄膜在正偏压下的主要漏电流输运机制为肖特基发射,而在负偏压下的主要漏电流输运机制为Frenkel-Poole发射。     

平栅极氧化锌场致发射电子源的制备及性能研究

采用传统的光刻技术制备平栅极场致发射阴极阵列,利用水热法原位合成ZnO发射源,并组装成平栅极ZnO场致发射电子源;利用光学显微镜、SEM和XRD表征其微观结构,分析ZnO发射源的生长机制,并结合场发射测试系统研究其发射特性。结果表明,ZnO发射源是平均直径为300nm的六方纤锌矿氧化锌纳米棒,且沉积在平栅极场致发射阴极阵列的阴极电极表面。场发射测试表明,平栅极ZnO场致发射电子源的发射特性完全由栅极控制。当阳极电压为2000V,器件的开启电压为150V;当栅极电压为275V时,发射电流可达345μA;在栅极电压为260V时,器件的发射电流波动范围为±5.5%左右,发光亮度高达750cd/m~2,表明该器件具有较好的场发射特性。     

SiO_2表面包覆改性钛酸钡/聚酰亚胺复合薄膜的制备与性能

以聚酰亚胺(PI)为基体,将聚酰亚胺与钛酸钡(BaTiO3)纳米粒子进行复合,采用原位聚合法制备BaTiO3/PI复合薄膜。为提高BaTiO3纳米粒子的分散性和表面性能,采用SiO2对BaTiO3纳米粒子进行表面包覆改性,并制备改性BaTiO3/PI复合薄膜。采用红外光谱、X射线衍射、扫描电镜等对制备得到的改性BaTiO3进行了表征,测试了复合薄膜的介电性能。结果发现,SiO2与BaTiO3粒子间仅是物理包覆,没有新物质形成。测试频率为103 Hz时,质量分数为5%的SiO2包覆改性使复合薄膜的介电常数增大到21.8,介电损耗为0.00521,击穿强度为76 MV/m,储能密度为0.56J/cm3。研究表明,采用SiO2对BaTiO3改性使得复合薄膜的介电性能有所提高。     

五层纳米SiO2-Al2O3/聚酰亚胺复合薄膜的制备及性能

采用浸胶法制备了一系列SiO₂-Al₂O₃/聚酰亚胺（SiO₂-Al₂O₃/PI）五层耐电晕薄膜A_m A_n PA_n A_m,其中中间层（P）为纯PI薄膜,外层（A_m）、次外层（A_n）分别为SiO₂-Al₂O₃掺杂不同质量分数的纳米SiO₂-Al₂O₃/PI薄膜。采用TEM、FTIR、宽频介电谱仪、电导电流测试仪、耐电晕测试仪、介电强度测试仪和拉伸实验机对五层纳米复合PI耐电晕薄膜的微观结构、介电性能和力学性能进行了表征和测试。结果表明,SiO₂-Al₂O₃/PI复合薄膜掺杂层形成了分布均匀的有机/无机复合结构;SiO₂-Al₂O₃纳米粒子的保护作用是影响复合材料耐电晕性能的主要因素,复合薄膜A₃₂A₁₆PA₁₆A₃₂的耐电晕寿命最大,为23.4 h;外层掺杂量对五层SiO₂-Al₂O₃/PI复合材料的介电强度影响较大,复合薄膜A₂₀A₂₈PA₂₈A₂₀的介电强度最大,为302.3 kV/mm;通过对五层复合结构的设计,可以在兼顾材料力学性能的同时,提高其耐电晕寿命和介电强度。     

CdSe/TiO2复合薄膜的制备及光电性能研究

以SeO2,CdCl2.5/2H2O,H2SO4为原料,采用三电极体系,分别在ITO玻璃和TiO2纳米管阵列基底上沉积CdSe薄膜。研究了不同沉积电压(-0.6,-0.7,-0.8,-0.9V,均相对于SCE)下制备的复合薄膜的晶体结构和微观形貌,并测试了其光电性能。结果表明:制备出的纳米粒子呈不均匀团聚状态;随沉积电压的增大,光吸收增强,光响应电流增大,在沉积电压为-0.8V时复合薄膜的光响应电流达到最大值,但此沉积电压下的薄膜容易剥落。综合考虑薄膜质量和光响应电流,沉积电压为-0.7V时制备的复合薄膜最佳。     

氧化锡薄膜场致发射研究

利用直流磁控反应溅射法,制备氧化锡薄膜,利用扫描电镜等方法对氧化锡薄膜微观结构进行分析。在低真空下,对不同厚度的氧化锡薄膜进行场致发射测试,结果显示,在氧化锡薄膜厚度为60nm时,场致发射性能最佳,当电流密度为10μA/m2时,开启电压为4.5 V/μm,阴阳两极电场为7 V/μm时,有较佳的场发射密度,同时发光亮度达到2180 cd/m2,结果表明,氧化锡薄膜在场发射平板显示及真空电子器件方面具有较好的应用潜力。     

大倍率二氧化硅/碳复合材料的制备及电化学性能表征

为了满足新能源储能及电动汽车对锂离子电池持续快速充电、慢速放电性能的要求,以正硅酸乙酯为二氧化硅前驱体,在两亲性炭材料(ACM)与聚乙二醇400(PEG400)形成的氢键限域体系中制备了大倍率二氧化硅/碳复合锂电负极材料(SiO_2-130/C)。材料表征结果表明,二氧化硅的粒径由500nm(未限域)降低到130nm(限域),同时,富碳的ACM在二氧化硅纳米颗粒表面构建了导电性良好的碳框架。在0.1A·g~(-1)和1A·g~(-1)的电流密度下,SiO_2-130/C的可逆比容量分别为527mAh·g~(-1)和347mAh·g~(-1),且在1A·g~(-1)的电流密度下连续400个充放电循环后,仍具有483 mAh·g~(-1)的可逆比容量,表现出优异的倍率性能及稳定的电化学性能。     

偶联剂对PI/SiO2 纳米复合材料形态结构及性能的影响——Ι

用溶胶2凝胶法成功地合成了PI/SiO₂ 纳米复合材料, 并用紫外-可见光谱、红外光谱、扫描电子显微镜等手段对硅烷偶联剂对其微观形态结构以及密度、溶解性等性能的影响进行了研究。研究结果表明, 偶联剂的加入对两相间起到很好的增容作用, 使得二氧化硅无机粒子的粒径大大减小, 分散更加均匀, 在宏观上表现为透明性提高, 所得P I/SiO₂ 纳米复合材料的溶解性有明显改善, 而且随偶联剂加入量的增加, 效果更加显著。另外, PI/SiO₂ 纳米复合材料的密度也随偶联剂量的增加而增大。     

Preparation and characterization of Bi2Ti2O7 thin films by chemical solution deposition technique

Transparent and crack-free Bi₂Ti₂O₇ thin films with strong (111) orientation were successfully prepared on n-Si(100) by chemical solution deposition (CSD) using bismuth nitrate and titanium butoxide as starting materials. The structural properties were studied by X-ray diffraction. The dielectric constant at 100 kHz at room temperature was 118 and loss factor was 0.074, for a 0.4-μm-thick film annealed at 500°C for 30 min. The leakage current density was 4.06×10⁻⁷ A/cm² at an applied voltage of 15 V.     

SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.     

核-壳结构粒子SiO_2@Bi_2O_3的制备及红外发射率研究

为了研究制备复合隐身粒子的方法,采用溶胶-凝胶法制备了核-壳结构SiO2@Bi2O3粒子.通过XRD、TEM及发射率测试仪对制备的材料的结构、形貌和性能进行了表征.XRD表明在700℃可以得到Bi2O3纯相;红外发射率测试表明,Bi2O3具有较低的红外发射率,在SiO2表面包覆Bi2O3后,在3～5μm和8～14μm两个测试波段都能降低SiO2的红外发射率.通过核-壳结构的形式,在较高发射率的样品表面涂覆红外发射率较低的样品,可以提高红外隐身效果.     

Microstructure developments of F-doped SiO2 thin films prepared by liquid phase deposition

This study presents a systematic investigation of the microstructure dependence of liquid phase deposition (LPD) of SiO₂ films on solution parameters and deposition temperature. The corresponding deposition rate and film roughness were also evaluated under various deposition conditions. Smooth and sufficiently dense SiO₂ films, which are the prerequisite for reliable low-k dielectric applications, were deposited on both silicon and fluorine-doped tin oxide coated glass substrates from supersaturated hydrofluorosilicic acid (H₂SiF₆) solution with the addition of boric acid (H₃BO₃). It is shown that H₂SiF₆ acid controls the surface morphology and grain structure through surface reaction while H₃BO₃ acid prompts bulk precipitation in solution. For the 208-nm thick SiO₂ film, the breakdown field exceeded 1.9 MV/cm and the leakage current density was on the order of 10^− 9 A/cm² at 4 V, indicating excellent insulating properties of LPD SiO₂ films. The strong presence of Si-O-Si and some Si-F with little Si-OH bond as shown in FT-IR spectra indicate that the LPD SiO₂ films have mostly a silica network with some fluorine (F) content. F-doping was self-incorporated into the silica films from the H₂SiF₆ solution during deposition process.     

Reactive sputtering of SiO2-TiO2 thin film from composite Six/TiO2 targets

Coatings of SiO₂-TiO₂ films are frequently used in a number of optical thin film applications. In this work we present results from depositing films with variable Si/Ti ratios prepared by reactive sputtering. The different Si/Ti ratios were obtained by varying the target composition of composite single targets. Compared to co-sputtering this facilitates process control and composition uniformity of the films. Varying the oxygen supply during sputter deposition can result in films ranging from metallic/substoichiometric to stoichiometric oxides. Transmittance spectra of the different films are presented and the optical constants are determined from these spectra. Furthermore, the deposition process, films structure and composition of the films are discussed. The study shows that by choosing the right composition and working in the proper oxygen flow range, it is possible to tune the refractive index.     

Annealing effect on dielectric and leakage current characteristics of Mn-doped Ba0.6Sr0.4TiO3 thin films as gate insulators for low voltage ZnO thin film transistor

We report on the dielectric properties and leakage current characteristics of 3 mol% Mn-doped Ba_0.6Sr_0.4TiO₃ (BST) thin films post-annealed up to 600 °C following room temperature deposition. The suitability of 3 mol% Mn-doped BST films as gate insulators for low voltage ZnO thin film transistors (TFTs) is investigated. The dielectric constant of 3 mol% Mn-doped BST films increased from 24 at in-situ deposition up to 260 at an annealing temperature of 600 °C due to increased crystallinity and the formation of perovskite phase. The measured leakage current density of 3 mol% Mn-doped BST films remained on the order of 5 × 10^− 9 to 10^− 8 A/cm² without further reduction as the annealing temperature increased, thereby demonstrating significant improvement in the leakage current characteristics of in-situ grown Mn-doped BST films as compared to that (5 × 10^− 4 A/cm² at 5 V) of pure BST films. All room temperature processed ZnO-TFTs using a 3 mol% Mn-doped BST gate insulator exhibited a field effect mobility of 1.0 cm²/Vs and low voltage device performance of less than 7 V.