溅射功率对CdZnTe薄膜成分和结构的影响

采用Cd0.9Zn0.1Te晶体作为溅射靶在玻璃衬底上利用磁控溅射法制备出CdZnTe薄膜,研究了溅射功率对CdZnTe薄膜的成分、结构特性的影响。制备的CdZnTe薄膜是具有闪锌矿结构的多晶薄膜,沿（111）择优取向。随着溅射功率的增大,薄膜沉积速率增大,薄膜结晶质量提高。采用晶体靶Cd0.9Zn0.1Te溅射CdZnTe薄膜时,无论是在何种功率下CdZnTe薄膜中的Cd原子成分均高于Te原子成分,Cd原子表现为择优溅射原子。     

铜铟硒薄膜的外延生长和表面重构及其电池性能研究

在GaAs的(110)、(001)和(111)A、(111)B等极性晶面上, 通过铜铟共溅-硒蒸镀的方法, 分布外延生长出(220/204)、(001)和(112)结晶取向的单晶CIS薄膜. 系统考察了CIS薄膜外延生长的结晶取向和表面微结构, 发现了这些CIS外延薄膜均需表面重构化而形成比表面能低的CIS(112)晶面, 结合晶体结构研究了各种晶面和比表面能的相关性. 通过各种衬底下不同结晶取向的CIS薄膜的太阳能电池组装, 发现当CIS薄膜生长具有(220/204)结晶取向时电池器件性能最好、效率最高, 说明可通过控制CIS薄膜的沉积条件和选用合适取向的衬底, 增加吸收层(220/204)的结晶取向, 从而显著提高CIS薄膜太阳电池的光电性能.     

真空蒸发沉积CdZnTe纳米薄膜的结构与形貌

采用真空蒸发沉积技术在ITO玻璃上制备得到CdZnTe纳米晶薄膜,并利用台阶仪、X射线能谱仪(EDS)、X射线衍射仪(XRD)和原子力显微镜(AFM)研究了CdZnTe薄膜厚度、成分、结构和形貌特征。实验结果表明,薄膜在(111)面表现出明显的择优生长特性。在薄膜生长初期,纳米薄膜中存在一定程度的非晶态富集Te,但随着沉积时间延长,薄膜成分向化学计量比逼近,结构也向闪锌矿CdZnTe转变。薄膜表面形貌平整,粗糙度Ra约为2～5nm。随着沉积时间的延长,薄膜形貌由晶粒堆砌状向多晶层片连接状转变。在沉积时间分别为15、30和45min时,薄膜的厚度依次分别约为100、300和500nm,而薄膜的晶粒平均尺寸依次分别为43.15、30.81和71.94nm。     

CdZnTe晶体沉淀物特性的研究

通过观察和分析CdZnTe晶体中富Te和富Cd沉淀物在红外透射显微镜下的形貌特征,从实验上证实在正四面体或八面体结构的富Te沉淀物内部存在空洞。分析表明,和正四面体沉淀物相邻的CdZnTe材料表面为(111)B面,构成八面体的另外4个面为(111)A面,(111)B面为表面能密度最低的慢生长面。结合化学腐蚀的观察结果发现,红外透射显微镜下呈星状结构的富Cd沉淀物由中心区沉淀物和外围高密度位错集聚区构成,中心区沉淀物大多为不规则形状。通过分析〈111〉和〈110〉晶向上富Cd沉淀物的形貌特征,确定了星状结构的延伸方向为〈211〉晶向,高密度位错集聚区的大小比沉淀物尺寸大出数倍。对沉淀物与周边材料的作用机理也进行了分析。     

氧化铝膜对铝诱导制备多晶硅薄膜的影响

为了考察硅铝界面氧化铝膜对铝诱导多晶硅的影响,本文用磁控溅射方法制备了界面有无氧化铝膜的硅铝复合结构。XRD测试表明两种铝诱导方法均制备了具有(111)高度择优取向的多晶硅薄膜。光学显微镜和扫描电镜照片显示,有氧化铝膜时铝诱导的多晶硅薄膜有两层,下层为大晶粒(40μm-60μm)枝晶状多晶硅,拉曼谱显示其结晶质量接近单晶,而上层膜晶粒较小,结晶质量较差。无氧化铝膜时铝诱导的多晶硅薄膜只有单层结构,其晶体结构和结晶质量都与有氧化铝膜时铝诱导的上层多晶硅薄膜相似。结果表明,硅铝界面上氧化铝的存在大大提高了铝诱导多晶硅薄膜的质量,但是另一方面也限制了铝诱导多晶硅的晶化速率。     

多晶硅薄膜的铝诱导晶化法制备及其晶粒的择优取向特性

采用铝诱导非晶硅薄膜晶化技术制备了多晶硅薄膜,并研究了多晶硅的成核和生长特性。非晶硅薄膜采用等离子体增强化学气相沉积法制备,其表面沉积铝薄膜后经不同温度的氮氛围退火处理。结果表明,退火后的硅薄膜层与铝层发生置换,所生长的多晶硅颗粒的平均尺寸约为150nm。X射线衍射分析结果揭示,薄膜的晶向显著依赖于退火温度,较低温度下,铝诱导晶化速率较慢,薄膜的优化晶向与非晶硅薄膜中团簇的初始原子排列趋势紧密相关。而较高温度下,铝诱导晶化促使多晶硅(111)择优成核及随后的固相生长。     

不同基底对掺镧钛酸铅铁电薄膜结晶性能的影响

采用射频磁控溅射技术,使用相同的工艺条件在Si(100)基底和Pt/Ti/SiO2/Si(100)基底上生长了掺镧钛酸铅[(Pb0.9,La0.1)TiO3,PLT10]铁电薄膜。采用常规热处理工艺对两种基底上生长的PLT铁电薄膜在相同条件下进行了退火。用原子力显微镜(AFM)观察PLT薄膜的表面形貌。用X射线衍射技术(XRD)研究PLT薄膜结晶性能。XRD图谱表明硅基底上的PLT在晶化后,各主要晶面的衍射峰均出现,取向呈现多样化;而在铂上的PLT在晶化后,只出现了(111)晶面衍射峰和(222)晶面衍射峰,取向是单一的〈111〉方向。通过对XRD的数据计算可知,在相同条件下退火的PLT薄膜,在铂上的PLT的晶粒尺寸大于在硅基底上的PLT的晶粒尺寸。晶粒尺寸的差异反应出了由于基底的影响而造成薄膜晶化过程中成核方式的差异。     

淬火致内应力对聚羟基丁酸戊酸酯薄膜结晶行为影响EI北大核心CSCD

通过对聚羟基丁酸戊酸酯(PHBV)薄膜进行低温淬火使薄膜形成不均匀内应力场,研究淬火致内应力对薄膜结晶行为的影响。用偏光显微镜对淬火样品结晶行为的研究结果表明,PHBV在90℃等温结晶形成环带球晶,但经低温淬火后再在90℃等温结晶却能形成取向结晶结构:当淬火温度(Tq)为-196℃时,形成横晶;当Tq为-80℃时,形成2种不同成核密度结晶结构;而Tq高于-20℃,只形成球晶。对横晶结构进行扫描电镜和X射线衍射表征,结果都显示片晶垂直于薄膜表面生长,表明结晶时分子链与薄膜平行,也进一步说明内应力是形成横晶结构的主要因素。     

铝膜沉积工艺对AIC法制备多晶硅薄膜的影响

采用真空热蒸发和磁控溅射两种方法沉积铝膜,通过对Glass/Si/SiO2/Al叠层结构进行铝诱导晶化(AIC)制备多晶硅薄膜。采用X射线衍射谱(XRD)、光学显微镜和拉曼光谱对样品进行分析,研究两种铝膜沉积工艺对AIC法制备多晶硅性能的影响。结果表明,采用两种方法沉积的铝膜均能诱导出(111)高度择优取向的大晶粒尺寸(～100μm)的多晶硅薄膜,但与磁控溅射沉积相比,真空热蒸发沉积的铝膜诱导出的多晶硅薄膜应力更小、结晶质量更高,且晶化速率更快。     

近空间升华法制备CdZnTe厚膜及其性能研究

采用近空间升华法在FTO玻璃衬底上制备CdZnTe多晶厚膜,并采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、紫外-可见光谱仪、I-V测试仪等对CdZnTe厚膜的表面形貌、成分、结构以及光电性能进行分析表征。结果表明,所制备的CdZnTe膜均匀致密,随生长时间的延长,晶粒尺寸明显增大;不同厚度的CdZnTe膜均表现出沿(111)晶面的择优生长;CdZnTe厚膜的禁带宽度在1.53～1.56eV之间;电阻率在1010Ω.cm数量级,具有较好的光电响应,试制的薄膜探测器可用作计数型探测器。     

蛋白质溶液的膜结晶：膜结晶法结晶溶菌酶的研究

用动态膜结晶法对溶茵酶结晶进行研究,考察了各种结晶条件对溶菌酶晶形和膜通量的影响,并对结晶条件进行优化,得到了质量较高的溶茵酶晶体.结果表明,当溶菌酶浓度为20～30 mg/n1L,结晶荆Naa浓度在40～90 g/L,洗脱剂MgCl2浓度在160～250 g/L,pH在4.7～8.2范围内,均能得到高质量的溶茵酶晶体.     

Spherical crystallization of celecoxib

Celecoxib exhibits poor flow properties and compressibility. Spherical crystallization of celecoxib was carried out using the solvent change method. An acetone:dichloromethane (DCM):water system was used where DCM acted as a bridging liquid and acetone and water as good and bad solvent, respectively. Hydroxypropylmethylcellulose (HPMC) was used to impart strength and sphericity to the agglomerates. The effect of amount of bridging liquid and speed of agitation was studied using 3² factorial design. Primary properties of the agglomerates were evaluated by infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry. The effect of variables on micromeritic, mechanical, compressional, and dissolution behavior was evaluated by response surface methodology. Particle size, bulk density, mean yield pressure (MYP), and drug release were found to be significantly affected by either of the two variables. Interaction of variables significantly affected the MYP.     

Protein crystallization in space

The microgravity environment of space is an ideal place to study the complicated protein crystallization process and to grow good-quality protein crystals. A series of crystal growth experiments of 10 different proteins was carried out in space on a Chinese re-entry satellite FSW-2 in August, 1992. The experiments were performed for about two weeks at a temperature of 18.5 +/- 0.5 degrees C using a tube-like crystallization apparatus made in the Shanghai Institute of Technical Physics, Academia Sinica. More than half of 48 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for hen-egg white lysozyme and an acidic phospholipase A2 from the venom of Agkistrodon halys Pallas. Analyses of the crystallization of these two enzymes in this mission showed that the microgravity environment in space may be beneficial to improve size, external perfection, morphology, internal order, and nucleation of protein crystals. Some of these positive microgravity effects were also demonstrated by the growth of protein crystals in gelled solution with the above two enzymes. A structural analysis of the tetragonal lysozyme crystal grown in space is in progress.     

Two-stage crystallization kinetics equation and nonisothermal crystallization analyses for PTEG and filled PTEG

A novel modified Avrami model considering both primary and secondary crystallization has been presented to extract the kinetic behavior of these two crystallization stages in nonisothermal crystallization process of polymers. Nonisothermal crystallization kinetics of poly(trimethylene terephthalate)–poly(ethylene glycol) segmented copolyesters (PTEG) has been investigated by differential scanning calorimetry. The crystallization rate constants and Avrami exponents at various cooling rates were obtained from the analyses for neat PTEG and multiwalled carbon nanotube (MWNT) filled PTEG. Secondary crystallization displays a lower-dimensional crystal growth compared with primary crystallization and the results of kinetics analyses are consistent with morphology study. The MWNTs introduced into PTEG matrix take the role of effective nucleating agents during composites crystallization and can expedite the process of crystallization of the matrix by providing more nucleation sites to the crystallizing phase.     

Millisecond crystallization of amorphous silicon films by Joule-heating induced crystallization using a conductive layer

This study revolved around the introduction of a crystallization technology for amorphous silicon film using Joule-heating. As part of this study, an electric field was applied to a conductive layer to induce Joule-heating in order to generate the intense heat needed to carry out the crystallization of amorphous silicon. Polycrystalline silicon was produced via Joule-heating through a solid state transformation under typical processing conditions. Uniformly distributed fine grains were obtained due to enormously high heating rate of this process. Crystallization was accomplished throughout the sample within the range of milliseconds of the heating, thus demonstrating the possibility of a crystallization route for amorphous silicon films at room temperature.     

Simulations on crystallization in polymers

Strain-induced crystallization has always been important in the area ofelastomers (since the crystallites thus generated provide substantial in situreinforcement) and can be simulated using Monte Carlo methods to generatechains having representative sequence distributions for differentpolymerization conditions. The chains are then placed alongside one anotherto determine matched-sequence runs that could lead to the formation ofcrystallites.     

Kinetics of calcium molybdate crystallization

Kinetics of crystallization of calcium molybdate from unstirred molten solutions of lithium chloride of low to medium supersaturation in platinum crucibles by the process of continuous cooling at 5° C hr⁻¹ from temperaturesT ₀=700 and 750°C are investigated. The crystal size measured by optical microscopy for different crystallization periods reveals that both crystal length and width generally increase with cooling period. The degree of crystallizationα _t,also increases with cooling period, attaining a maximum of 0·90. The diffusion rate constants,K _Dlat 700 and 750°C are 0·0776 and 0·1138 respectively. The effect of variation of the crystallization temperature on the crystal size and their number is also studied.     

Hydrothermal crystallization of piperazine-ZSM-39

The crystallization of PIP-ZSM-39 from the reaction mixtures (15−x)PIP xNaA 20SiO₂ 250H₂O at 180°C is reported for x=0, 0.5, 1, 2, 5, and A=OH⁻, SO_4²⁻ or CO_3²⁻. For x=0 large (200 μm) octahedral crystals are formed in 16 days; for x≠0 crystallization is faster but the crystals are smaller and less well-formed. At higher pH values the reactions overrun to quartz.