类金刚石膜中应力释放花样形貌分析

用Ｒａｍａｎ谱研究了射频－直流等离子体化学气相沉积法制备的类金刚石膜结构，，用弯曲法研究了类金刚石膜的应力，用光学显微镜对类金刚石膜肿由于压应力的释放所形成的花样形貌进行了观察。类金刚石膜中存在１－４．７ＧＰａ的压应力。由于应力释放，在膜－基界面处观察到正弦曲线状，分枝状，直线状和花状花样外，还观察到时钟状和水泡状两种新型应力释放花样，用薄板起皱理论可以很好地解释这两种新花样。     

钢渗铬层上金刚石薄膜的表面、界面结构及附着性

在钢渗铬层表面用化学气相沉积(CVD))法制备了金刚石薄膜.使用扫描电镜(SEM)、透射电镜(TEM)和压痕法研究了金刚石膜的表面、界面结构及附着力.用拉曼光谱分析了金刚石膜的纯度及非金刚石碳相.甲烷含量超过0.6%(体积分数)后,金刚石膜为球形纳米晶,形核密度＞107cm-2.用甲烷含量为0.6%(体积分数)沉积的金刚石膜表面的残余压应力为1.22 Gpa,而膜背面的残余压应力更高,达2.61 Gpa.压痕显示在19.6 N载荷下膜发生开裂.TEM观察发现,膜/基界面为微观非平面,有利于提高金刚石膜的附着力.     

热阴极DC-PCVD方法制备的金刚石厚膜的生长特性和内应力

采用热阴极DC PCVD(DirectCurrentPlasmaChemicalVaporDeposition)方法制备出大尺寸高质量的金刚石厚膜,研究了金刚石厚膜的生长特性和内应力状态。由热阴极DC PCVD方法制备的金刚石厚膜大多数为〈110〉取向,表面显露面主要是(100)面和(111)面,厚膜的表面被较多的孪晶所覆盖,部分(111)面退化为3个相互垂直的(110)面,孪晶使厚膜表面结晶特性复杂化,金刚石厚膜的晶粒沿生长方向呈现柱状生长。金刚石厚膜的生长速率随甲烷流量和工作气压的增加而增加,但随生长速率的提高金刚石膜的品质明显下降。金刚石厚膜的内应力以压应力为主,随着甲烷浓度的增加压应力增加,随着工作气压的增加压应力减小,到某个气压之后变为张应力。     

钢渗铬沉积金刚石膜的研究

用热解CVD装置研究了甲烷浓度、基底温度、室压对钢渗铬沉积金刚石膜的影响.结果表明,甲烷浓度越低,沉积得到的金刚石膜的晶形越好,甲烷浓度超过0.8%后,金刚石的形貌呈"菜花状";基体温度高时,难于在渗铬层上形成连续的金刚石膜,但基体温度高所得的晶形较好;室压越高,金刚石的形核密度越高,但随室压的升高,金刚石的形貌变差.菜花状金刚石膜是由大量二次晶核长大的微晶金刚石晶粒组成,含有较多的非金刚石碳相.     

金刚石薄膜压阻效应及相关问题的研究

P型金刚石薄膜具有压阻效应,是最近五六年才发现的新现象。利用压阻效应,可望将金刚石膜制成高灵敏度的新一类压阻传感器材料和压力微传感器,从而拓宽金刚石膜在电子学领域的应用范围。 对金刚石膜的压阻因子进行了测量,结果表明,P型定向生长的多晶金刚石膜室温压阻因子可达100O以上;金刚石薄膜的压阻效应比硅和金属显著得多;多晶金刚石膜的压阻效应不如单晶金刚石膜。金刚石膜具有显著的压阻效应,其理论原因和机制问题到目前一直不太清楚,本研究工作对此进行了系统和深入的研究。在能带结构和形变势理论的基础上,首次结合价带分裂模型和M-S多晶模型,分别推导出P型单晶和多晶金刚石膜压阻因子的近似计算公式。分析结果认为,金刚石薄膜的压阻效应是应力诱导价带分裂造成的。轻、重空穴有效质量之间的巨大差异,是导致P型金刚石具有显著压阻效应的主要原因之一。P型多晶材料的压阻效应,是应力诱导价带分裂和晶界散射联合作用的结果,晶界有阻碍电阻随应变发生改变的作用。从而,第一次从理论上阐明了导致P型多晶材料压阻效应不如同种的P型单晶材料的原因。 对负偏压热灯丝CVD系统下,金刚石膜核化过程进行了研究,结果认为.负偏压对金刚石膜核化的增强是离子对衬底的轰击与发射电子激发的等离子体联合作用于衬     

用压痕试验法研究CVD金刚石膜的粘附性能

在观察与分析压入过程中CVD金刚石膜开裂方式的基础上,初步探讨了用压痕试验法评定CVD金刚石膜粘附性能的可行性．采用反映膜／基粘附性能的临界开裂或剥落载荷P_er和抗裂性参数dP／dX两指标评定了硬质合金基体表面经不同预处理方法和沉积工艺参数合成的金刚石膜的粘附性能;研究了粘附性能指标与沉积工艺参数（如甲烷浓度、沉积气压、沉积功率）之间的关系．适当的表面预处理、适中的甲烷浓度、较低的沉积气压、较高的沉积功率均有利于改善金刚石膜的粘附性能．     

金刚石膜中氮杂质状态的研究

用EA-CVD(Electron assisted Chemical Vapor Deposition)方法制备出金刚石膜,并且用拉曼光谱、荧光谱、红外吸收谱和顺磁共振谱研究了金刚石膜中的氮杂质.实验结果表明,用EA-CVD方法制备的金刚石膜中氮杂质主要是以Ns0、Ns+、[N-V]0和[N-V]-1的形式存在,没有检测到在天然金刚石和高温高压金刚石中常见的A和B中心形式存在的氮杂质.沉积实验中随着氢气流量的增加,也就是金刚石膜沉积环境中氮浓度的减少,金刚石膜中氮杂质含量减少.     

无支撑优质金刚石膜研制中的相关问题探讨

无支撑优质金刚石膜在微波真空器件和光学器件中的广泛应用,有赖于制备成本的下降和工艺的完善。结合微波等离子体化学气相沉积(MPCVD)金刚石膜的工艺研究结果,本文就沉积速率、晶面取向以及内应力的相关问题进行了初步探讨。对于给定的设备,沉积速率与多种因素有关,包括膜的质量、膜厚均匀性和有效沉积面积、以及形核的密度。在通常情况下,金刚石膜呈(111)择优取向,而样品位置下移5mm后,观察到(100)取向。对内应力的初步研究表明,CH4/H2比例较低(1.5)时,金刚石膜的内应力趋向于压应力,而(100)取向的出现则有助于使内应力降到最低。     

氧等离子体对金刚石膜的刻蚀研究

用微波放电法产生氧等离子体，通过改变系统中氧的浓度和金刚石膜的温度研究了氧等离子体对CVD多晶金刚石膜刻蚀的影响。实验结果表明：随着氧浓度的增加和金刚石膜温度的提高，刻蚀作用加剧；而在较低的氧浓度和金刚石膜温度条件下金刚石膜的晶界处首先被刻蚀，说明金刚石膜的境界处含有较多的非金刚石碳相。并且从等离子体对(100)和(111)面的刻蚀现象可知(100)面的生长是二维生长，(111)面的生长是岛状生长。     

在低合金钢基体表面沉积镶嵌结构界面金刚石膜

在低合金钢基体上磁控溅射镀Cr/Cu双层膜,电沉积铜-金刚石复合过渡层,在热丝CVD系统中沉积了连续的金刚石膜。用压痕实验研究了所沉积的金刚石膜/基结合性能,用扫描电镜(SEM)、X射线(XRD)、拉曼光谱表征了金刚石膜的表面形貌、相结构和内应力。结果表明,经CVD金刚石沉积后Cr层转化为铬铁碳化物层,阻止了Fe对界面金刚石的石墨化,并部分缓冲相变应力;较软的Cu层能有效缓解相变应力和热应力,降低了所沉积的金刚石膜内应力;用441N载荷对所沉积的金刚石膜进行压痕评估,压痕外缘只产生环状裂纹,表明膜基结合力较高。     

Stress relief forms of diamond-like carbon thin films under internal compressive stress

An optical microscope study of the stress relief forms of diamond-like carbon thin films is presented in this paper. The dimensions of the stress relief patterns are shown to be proportional to the film thickness. Three stress relief forms are distinguished. They are analysed in the framework of the linear theory of plate buckling. The forms of the stress relief correspond to two different solutions of the differential equations.     

Stress relief patterns of Co films deposited on circular silicone oil substrates

By using the expansive and mobile properties of silicone oil, circular liquid substrates with varied thicknesses naturally form on clean glass surfaces during deposition. Continuous cobalt (Co) films have been prepared on the circular liquid substrates by a direct current magnetron sputtering method, and the stress relief patterns of the Co films are investigated. The experiment shows that the Co film is susceptible to generating cracks due to thermal expansion of the silicone oil substrate during deposition. After deposition, subsequent cooling of the system creates a high compressive stress in the film, which is relieved by formation of various wrinkling morphologies. Based on the special growth mechanism and mechanical properties of the metal film deposited on a liquid substrate, the structural characteristics of the stress relief patterns and the underlying physical mechanisms are discussed in detail.     

Influence of dopant concentration on the optical properties of ZnO: In films by sol-gel method

Undoped and In doped ZnO films have been deposited by sol-gel spin coating method. The effect of indium incorporation on structural and optical properties of ZnO films has been investigated. X-ray diffraction patterns of the films showed the hexagonal wurtzite type polycrystalline structure and that indium incorporation leads to substantial changes in the structural characteristics of ZnO films. The SEM and AFM measurements showed that the surface morphology of the films was affected from the indium incorporation. Optical reflectance and transmittance were recorded with a double beam spectrophotometer with an integrating sphere. The optical band gap of these films was determined. The absorption edge shifted to the lower energy depending on the dopant materials. The optical constants of these films were determined using transmittance and reflectance spectra.     

Optical and structural properties of Mg doped ZnO thin films by chemical bath deposition method

The chemical bath deposition method has often been employed to successfully deposit pure and Mg doped ZnO thin films on a glass substrate. The impact of Mg creates a strained stress in ZnO films affecting its structural and optical properties. XRD patterns revealed that all thin films possess a polycrystalline hexagonal wurtzite structure and Mg doped ZnO thin films (002) plane peak position is shifted towards a lower angle due to Mg doping. From the SEM image, it is understood that the Mg doped ZnO thin films are uniformly coated and are seen as dense rods like pillers deposited over the film. The energy dispersive X-ray analysis confirmed the presence of Mg in doped ZnO thin films. The transmittance spectra exhibit that it is possible for Mg doping to enhance ZnO thin films. The optical energy gap of the films was assessed by applying Tauc’s law and it is observed to show an increasing tendency with an improvement in Mg doping concentrations. The optical constants such as reflectance, index of refraction, extinction coefficient and optical conductivity are determined by using transmission at normal incidence of light by using wavelength range of 200–800 nm. In PL spectra, the band edge emission shifted to the blue with increasing amount of Mg doping.     

Analysis of long-term internal stress and film structure of SiO2 optical thin films

Recently, the demand for durability of optical thin films, which have long been used, has been growing as the performance of optical components improves. The stress of a film is an important parameter that is related to its adhesion. The electron beam (EB) and ion-assisted deposition (IAD) methods are widely used to fabricate optical thin films. However, there are few reports on long-term internal stress, despite the importance of this issue. Here we discuss the time dependence of the stress of SiO2 optical thin films in terms of optical characteristics in the infrared region. It was found that SiO2 thin films prepared by the EB and IAD methods exhibited compression stress. The Si-OH molecular bond was observed at around 930?cm(-1) in the Fourier transform infrared spectroscopy spectrum of the sample prepared by the EB method, which exhibited a large change in internal stress after an elapsed time. It is considered that this change in bonding was related to the decrease in the stress of the films.     

In-situ observation of transition between surface relief and wrinkling in thin film shape memory alloys

Significant surface morphology evolution between relief and wrinkling was observed on a 3.5 microm thick TiNiCu film sputter-deposited on a silicon substrate. At room temperature, variation in surface relief morphology (from separated martensite crystals embedded in amorphous matrix to fully interweaved martensite plates) was observed with slight change in film composition. The phenomenon was attributed to variations in crystallization temperatures of as-deposited amorphous films during annealing because of the compositional difference. During thermal cycling between room temperature and 100 degrees C, reversible surface morphology changes can be observed between surface relief and wrinkling patterns. The formation of the surface wrinkling is attributed to the large compressive stress in the film during high temperature post-annealing and crystallization, whereas surface relief is caused by the martensitic transformation to relieve the large tensile stress in the film. Compositional effect on this surface morphology evolution is discussed. Results also indicate that there is a critical dimension for the wrinkling to occur, and a small circular island can only relax by in-plane expansion.     

Effect of thermal annealing on the optical properties and residual stress of graded-index-like films deposited by radio-frequency ion-beam sputtering

Composite films of Ta-Si oxide and graded-index-like films have been realized by using radio-frequency ion-beam sputtering. The influence of thermal annealing on the optical properties and residual stress of single-layer composite films and graded-index-like films has been studied. The residual stress and optical properties of both types of films were more stable than that of the notch filters fabricated from a series of discrete quarter-wave layers made by alternatively stacking high and low index materials after annealing.     

Ga-Ti共掺杂ZnO透明导电薄膜的微观结构和光电性能研究

采用磁控溅射方法在玻璃基片上制备了Ga-Ti共掺杂ZnO(GTZO)透明导电薄膜,通过XRD、四探针仪和分光光度计测试,研究了氩气压强对GTZO薄膜光电性能和晶体结构的影响。结果表明:所有GTZO薄膜均为(002)择优取向的六角纤锌矿结构,其光电性能和晶体结构与氩气压强密切相关。当氩气压强为0.4Pa时,GTZO薄膜具有最大的晶粒尺寸(85.7nm)、最小的压应力(-0.231GPa)、最高的可见光区平均透射率(86.1%)、最低的电阻率(1.56×10-3Ω·cm)和最大的品质因子(4.28×105Ω-1·cm-1),其光电综合性能最佳。另外,采用光学表征方法计算了薄膜的光学能隙和折射率,并利用有效单振子理论对折射率的色散性质进行了分析,获得了GTZO薄膜的色散参数。     

Stress relief mechanism of aging in plated-wire memories

Results are presented which identify a dominant aging mechanism of plated-wire memory elements in the absence of magnetic fields. This mechanism, i.e., stress relief in the Permalloy film, can occur even in elements stabilized against field-induced aging. The evidence for stress relief consists of aging and strain sensitivity measurements on samples of different Permalloy composition. In aging experiments under vacuum at 230°C, Ni-rich films show an increase in anisotropy field Hk, while Fe-rich films show a decrease. A stress relief model is described which relates such aging changes to the initial film stress the cylindrical geometry, and the tension strain sensitivity. Using this model, agreement is found between film stress deduced from the Hkaging changes, and film stress from direct measurements, reported in the literature. Films which are judged to have zeromagnetostrictive composition (ZMC) on the basis of torsion sensitivity are found to show nonzero tension sensitivity. This is satisfactorily accounted for by circumferential composition inhomogeneity, which is shown analytically to explain the observed decrease in anisotropy field with tension. It is concluded that reduction of such inhomogeneity by appropriate deposition techniques is favorable to both smaller strain sensitivity and increased aging stability.