生长条件对脉冲激光沉积制备ZnO：Al薄膜光电性能的影响

本文研究了脉冲激光沉积(PLD)生长过程中, 铝掺量、氧压及衬底温度等实验参数对ZnO:Al(AZO)薄膜生长的影响, 并利用扫描电子显微镜、原子力显微镜、X射线衍射、霍尔效应、光透射光谱等实验手段对其透明导电性能进行了探讨. 变温霍尔效应和光透射测量表明, 当靶材中铝掺量大于0.5 wt%时, 所制备AZO薄膜中铝施主在80 K时已完全电离, 因Bernstein-Moss (BM) 效应其带隙变大, 均为重掺杂简并半导体. 进一步系统研究了氧压和衬底温度对AZO薄膜透明导电性能的影响, 实验发现当氧压为1 Pa, 衬底温度为200 ℃时, AZO 导电性能最好, 其霍尔迁移率为28.8 cm²/V·s, 薄膜电阻率最小可达2.7×10^-4 Ω·cm, 且在可见光范围内光透过率超过了85%. 氧压和温度的增加, 都会导致薄膜电阻率变大. 关键词： 脉冲激光沉积法 ZnO：Al薄膜 透光性 导电性     

Si衬底对ZnO薄膜性能影响的研究

使用脉冲激光沉积(pulsed laser deposition, PLD)技术,采用两种不同纯度(99.5%和99.99%)的ZnO靶材,在p型Si衬底上制备了两种ZnO/Si薄膜.原子力显微镜与X射线衍射分析表明,两种样品具有相似的显微形貌与相同的晶体结构.霍尔效应测试发现,两种ZnO/Si薄膜都展现出了低电阻率、高迁移率的电学性能,但是其导电类型完全相反.研究结果表明,衬底的性能对霍尔效应测试有巨大影响.利用二次离子质谱仪,发现了在低纯度的样品中存在着S杂质向Si衬底中扩散的现象,并直接导致了衬底的导电性能的反型.     

Ag掺杂p型ZnO薄膜及其光电性能研究

采用超声喷雾热分解法在石英衬底上以醋酸锌水溶液为前驱体,以硝酸银水溶液为Ag掺杂源生长了Ag掺杂ZnO(ZnO：Ag)薄膜.研究了衬底温度对所得ZnO：Ag薄膜的晶体结构、电学和光学性质的影响规律.所得ZnO：Ag薄膜结构良好,在室温光致发光谱中检测到很强的近带边紫外发光峰,透射光谱中观测到非常陡峭的紫外吸收截止边和较高的可见光区透过率,表明薄膜具有较高的晶体质量与较好的光学特性.霍尔效应测试表明,在500℃下获得了p型导电的ZnO：Ag薄膜,载流子浓度为5.30×10¹⁵cm关键词： ZnO：Ag薄膜 p型掺杂 超声喷雾热分解 霍尔效应     

小型烧结炉装置的设计与制作

设计与研制了一种小型的用于制备薄膜样品电接触的烧结炉装置，该装置简单、实用、特别适用于半导体霍尔样品电极的烧结。     

近距离升华沉积CdTe掺Cd薄膜的微结构和电学、光学特性

采用近距离升华技术制备了掺杂Cd元素的CdTe多晶薄膜.利用X射线衍射仪和扫描电子显微镜表征其微结构,用霍尔效应测试仪和紫外可见分光光度计分析其电学、光学特性.结果显示,适量的掺杂Cd元素可改善CdTe薄膜晶形,显著提高薄膜的电导特性,由弱的p型电导转变为导电性能良好的n型电导,但对光能隙影响不大. 关键词： 近距离升华 CdTe薄膜 掺杂Cd 电学和光学特性     

演示小位移传感器的装置制作

本文介绍了半导体材料的霍尔效应及磁阻效应,讨论了霍尔磁阻元件的特性,提出位移传感器的工作原理、结构设计,并详细说明安装和调试过程.演示装置结构简单、物理概念清晰、易于操作.它将磁场的变化无接触转化为材料的电阻变化,从而把与磁场变化相联的位移形式转化为电信号输出,形成位移传感器.由实验数据和图示曲线表明:测量桥路输出电压随磁钢和霍尔片之间的距离变化而变化;另外,测量桥路的测量灵敏度随工作电流IC增加而提高.通过本装置可以对霍尔磁阻效应、一种小位移测量传感器原理和方法进行演示和探究.在课堂教学、课程设计等场合,直观显示霍尔元件的各种效应和技术应用,有着良好的教学效果.     

Hg_(1-x)Cd_xTe材料变温特性的实验研究

对碲镉汞(Hg1-xCdxTe)材料的电学特性进行了变温实验研究.通过变温(80~300 K)霍尔效应测量,研究了Hg1-xCdxTe材料的霍尔系数RH、电导率σ和霍尔迁移率μH的温度依赖关系.结果表明,Hg1-xCdxTe晶体在低温下为p型导电,而在室温下为n型导电.     

基于变均布霍尔系数的磁控热防护系统霍尔效应影响

为研究霍尔效应对磁控热防护系统的影响机理,建立并验证了热化学非平衡流场、外加磁场、感应电场的多场耦合数值求解方法.基于均布霍尔系数模型分析了霍尔效应在两种不同磁场强度B_0、不同壁面导电条件下对磁控效果的影响.研究表明,不同壁面导电性下霍尔效应的影响规律不同.绝缘壁面条件下,考虑霍尔效应后壁面热流的变化是附面层内洛伦兹力的变化与激波层厚度的减小二者共同作用的结果.B_0=0.2 T时洛伦兹力增加附加的流体减速作用占主导,磁控热防护效果优于忽略霍尔效应的情况,并且在霍尔系数为5.0达到最优;而当B_0=0.5 T时,激波层变薄对附面层外缘温度的增加占主导,磁控热防护效果变差,并且随霍尔系数的增加壁面热流越来越大.导电壁面条件下,随着霍尔系数的增加,磁控激波以及热防护效果变差,且当β≥5.0时,磁控热防护系统几乎完全失效.     

感压复合材料压阻性能

随着机械装置向结构复杂化发展，常需要对复杂装置的层间挤压应力等接触应力进行研究，这需要利用薄型挤压应力传感器来进行接触测量。进行层间接触测量的传感器不但应具备良好的应力敏感特性，而且应具有优良的柔韧力学性能，选用高导电纳米炭黑、球形石墨为导电粒子，硅橡胶、天然橡胶为基材开展了颗粒填充型导电高分子复合材料的配方工艺优化研究、薄膜制备及均匀性控制方法研究及感压复合材料薄膜的压力一电阻关系研究。     

磁性拓扑绝缘体中的量子化反常霍尔效应——无需外磁场的量子化霍尔效应

文章从平常霍尔效应出发,介绍了反常霍尔效应及其内秉物理机制,并在此基础上介绍了其量子化版本——量子化反常霍尔效应.然后从拓扑有序态的角度,重点讨论了量子化反常霍尔效应与量子霍尔效应、量子自旋霍尔效应、拓扑绝缘体等之间的区别与内在联系.最后介绍了通过在拓扑绝缘体(Bi2Se3,Bi2Te3和Sb2Te3)薄膜中掺杂过渡金属元素(Cr或Fe)实现量子化反常霍尔效应的方法.     

Residual stress induced wetting variation on electric brush-plated Cu film

Nanocrystalline Cu film with a mirror surface finishing is prepared by the electric brush-plating technique. The as- prepared Cu film exhibits a superhydrophilic behavior with an apparent water contact angle smaller than 10°. A subsequent increase in the water contact angle and a final wetting transition from inherent hydrophilicity with water contact angle smaller than 90° to apparent hydrophobicity with water contact angle larger than 90° are observed when the Cu film is subjected to natural aging. Analysis based on the measurement of hardness with nanoindentation and the theory of the bond-order-length-strength correlation reveals that this wetting variation on the Cu film is attributed to the relaxation of residual stress generated during brush-plating deposition and a surface hydrophobization role associated with the broken bond polarization induced by surface nanostructure.     

Contact ratio of rough surfaces with multiple asperities in mixed lubrication at high pressures

Relative optical intensity interference was used to measure the lubrication film thickness when four kinds of polyalphaolefin (PAO) were used as lubricants confined between a smooth sapphire disc surface and a rough steel ball surface. Maximum Hertz contact pressure up to 3 GPa was applied in the central part of the contact region in mixed lubrication. It was found that the contact ratio (the ratio of real contact region to the whole nominal contact region) is related to the film thickness, the applied pressure, the surface roughness and the rolling speed, and so on. Contact ratio evidently reduces as lubrication film thickness or rolling speed increases. Quantitative relationship between the contact ratio and the influence factors was summarized based on the nonlinear fitting of experimental measurements. A formula was put forward to calculate the contact ratio at high pressure conditions according to the current experimental results.     

Preparation of hybrid film with superhydrophobic surfaces based on irregularly structure by emulsion polymerization

A superhydrophobic surface originated from quincunx-shape composite particles was obtained by utilizing the encapsulation and graft of silica particles to control the surface chemistry and morphology of the hybrid film. The composite particles make the surface of film form a composite interface with irregular binary structure to trap air between the substrate surface and the liquid droplets which plays an essential role in obtaining high water contact angle and low water contact angle hysteresis. The water contact angle on the hybrid film is determined to be 154 ± 2° and the contact angle hysteresis is less than 5°. This is expected to be a simple and practical method for preparing self-cleaning hydrophobic surfaces on large area.     

矩形毛细微槽中三角形区域接触线特性的研究

利用CCD和宽视场体视显微镜相结合的技术,拍摄了矩形毛细微槽内液体工质在三角形区域的润湿图像,并进行了图像处理,研究结果表明:随着热流密度的增加,三角形区域内的三相接触线向微槽底角收缩,导致三相接触线的长度减小,液膜厚度减小;随着微槽深度的增加,三角形区域的接触线长度减小;随着微槽宽度和倾斜角度的增加,三角形区域内的接触线长度增加,液膜厚度增加.     

Surface modification of diamond-like carbon films with perfluorooctyl functionalities and their surface properties

Photolysis of perfluoroazooctane with diamond-like carbon (DLC) films led to the surface modification to introduce perfluorooctyl functional groups, confirmed by means of FT-IR, XPS, Raman and TOF-SIMS measurements. The DLC films modified with fluorine moieties showed reduction of the surface energy evaluated by contact angle to water, as compared with pristine DLC film. The contact angle of chemically modified DLC film is 105°, comparable to that of polytetrafluoroethylene (PTFE). By monitoring with XPS, we found that the results on the value of fluorine/carbon ratio of fluorinated DLC films depending on irradiation time are consistent with those of contact angle. Chemical modification of DLC films with perfluorooctyl functionalities also led to improvement of their frictional properties. The friction coefficient of the modified film is 0.05 under vacuum condition, whereas that of the pristine film shows very high value (>1).     

基于氧化镍背接触缓冲层碲化镉薄膜太阳电池的研究

采用电子束蒸发法制备了NiO薄膜,并对其作为碲化镉薄膜太阳电池背接触缓冲层材料进行了相关研究.NiO缓冲层的加入使得碲化镉太阳电池开路电压显著增大.通过X射线光电子能谱测试得到的NiO/CdTe界面能带图表明NiO和CdTe的能带匹配度很好.NiO是宽禁带P型半导体材料,在电池背接触处形成背场,减少了电子在背表面处的复合,从而提高电池开路电压.通过优化NiO薄膜厚度,制备得到转换效率为12.2%、开路电压为789 mV的碲化镉太阳电池.研究证实NiO是用来制备高转换效率、高稳定性碲化镉薄膜太阳电池的一种极有前景的缓冲层材料.     

Formation process of a strong water-repellent alumina surface by the sol-gel method

A novel strong water-repellent alumina thin film is fabricated by chemically adsorbing stearic acid (STA) layer onto the porous and roughened aluminum film coated with polyethyleneimine (PEI). The formation process and the structure of the strong water-repellent alumina film are investigated by means of contact angle measurement and atomic force microscope (AFM). Results show that the water contact angles for the alumina films increase with the increase of the immersion time in the boiling water, and meanwhile, the roughness of the alumina films increases with the dissolution of the boehmite in the boiling water. Finally, the strong water-repellent film with a high water contact angle of 139.1° is obtained when the alumina films have distinct roughened morphology with some papillary peaks and porous structure. Moreover, both the roughened structure and the hydrophobic materials of the STA endow the alumina films with the strong water-repellence.     

Non-Newtonian thin films with normal stresses: dynamics and spreading

The dynamics of a thin film on a horizontal solid substrate is investigated in the case of non-Newtonian fluids exhibiting normal stress differences, the rheology of which is strongly non-linear. Two coupled equations of evolution for the thickness of the film and the shear rate are proposed within the lubrication approximation. This framework is applied to the motion of an advancing contact line. The apparent dynamic contact angle is found to depend logarithmically on a lengthscale determined solely by the rheological properties of the fluid and the velocity of the contact line.     

Enhanced optical and hydrophilic properties of V and La co-doped ZnO thin films

V and La co-doped and undoped ZnO thin films were deposited on a glass substrate via the sol–gel method to investigate the structural, optical, and wettability of ZnO thin film by changing the V-doping concentration. Microstructure and water contact angles of the films were measured by SEM and contact angle goniometer, respectively. SEM studies revealed that the grain size and surface roughness of the film were changed by doping concentration. In addition, the contact angles were studied to find the possible effects of doping on the hydrophilicity of the film, indicating that the ZnO films were hydrophobic in nature. Finally, a good correlation was observed between the SEM micrographs and contact angle results, and the nature of ZnO film was found to be changed from hydrophobic to hydrophilic.     

Quantification of patellofemoral joint contact area using magnetic resonance imaging

To describe a method for quantifying patellofemoral joint contact area using magnetic resonance imaging (MRI), we used a repeated measures design using cadaver specimens. The use of contact area obtained from cadaveric specimens for biomechanical modeling does not permit investigators to assess the inter-subject variability in contact area as a result of patellofemoral pathology or malalignment. Therefore, a method for measuring patellofemoral joint contact area in-vivo is necessary. Six fresh frozen unmatched human cadaver knees were thawed at room temperature and minimally dissected to permit insertion of a pressure sensitive film packet into the suprapatellar pouch. A custom loading apparatus was designed to apply a compressive load to the patellofemoral joint at 30 degrees of flexion. Simultaneous measurement of contact area was made using both the pressure sensitive film technique and MRI. The intraclass correlation coefficient (ICC) and coefficient of variation were used to compare the agreement between the two methods and to assess the repeatability of the MRI method. Good agreement was found between the MRI and pressure sensitive film techniques (ICC 0.91; CV 13%). The MRI technique also was found to be highly reproducible (ICC 0.98; CV 2.3%). MRI assessment of patellofemoral joint contact area was found to be comparable to the established pressure sensitive film technique. These results suggest that this method may be a valuable tool in quantifying patellofemoral joint contact area in-vivo. Quantification of the patellofemoral joint stress has been dependent on patellofemoral joint contact area obtained from cadaver specimens, thereby negating the potential influence of subject specific variability. Developing a non-invasive technique to evaluate contact area will assist researchers and/or clinicians in obtaining patient-specific contact area data to be used in biomechanical analyses and clinical decision making.