金刚石薄膜热沉的开发

本文综述了金刚石热沉的发展过程,指出了开发金刚石薄膜热沉的意义,介绍了用直流电弧等离子体喷射法制备的金刚石薄膜的热性质以及金刚石薄膜热沉表面的抛光和金属化方法。     

新金刚石科学技术

本文介绍了低压化学气相合成金刚石的历史、金刚石薄膜的沉积方法、特点及机理，阐述了国内外金刚石薄膜技术的发展动态。     

H2-O2混合气氛刻蚀制备金刚石纳米晶薄膜

提供了在镜面抛光Si衬底上沉积平滑的纳米金刚石（NCD）薄膜的方法。采用微波等离子体化学气相沉积（CVD）系统，利用H2、CH4和O2为前驱气体，在镜面抛光的Si基片上制备了直径为5cm的NCD薄膜，用扫描电镜（SME）和共焦显微拉曼光谱分析其表面形貌和结构特点。分析表明，利用这种方法可以制备出高sp^3含量的NCD薄膜。通过与沉积时间加长而沉积条件相同情况下合成的金刚石微晶薄膜形貌相对比，分析了H2-O2混合气氛刻蚀制备NCD薄膜的机理。分析表明，基底的平滑度对O2的刻蚀作用起到重要的影响；在平滑的基底上，含量较少的O2的刻蚀作用也很明显；随着基底的平滑度下降，混合气氛中O2的刻蚀作用逐渐减弱。     

宽禁带半导体金刚石

较详细地叙述了当前国内外正处在研究热潮中的金刚石半导体的优越性质、发展状况及其应用和潜在的应用前景.同时分析和比较了金刚石薄膜的各种制备方法,可以看出微波等离子体化学汽相沉积法是较好的制备金刚石薄膜的生长技术,并且分析了该技术的特点和优势.该法在保持适当氩气氛和施加衬底负偏压下还可进一步提高金刚石膜的生长速率和质量.对于金刚石异质(在硅衬底上)成核的基本机理也进行了分析.最后,阐述了研究金刚石半导体薄膜目前需要解决的关键问题及其发展方向.     

双光束复合脉冲激光辐照沉积纳米金刚石薄膜

利用双光束复合脉冲激光辐照石墨悬浮液沉积技术,制备了高效率、高质量的纳米金刚石薄膜,成功解决了金刚石薄膜沉积不均匀和衬底温度对金刚石薄膜的影响。通过拉曼光谱仪和高分辨率透射电镜对薄膜的微观结构和组成进行了检测分析,实验结果表明,Raman光谱的D峰出现在1334cm-1处,G峰出现在1571cm-1处,沉积的薄膜致密均匀,晶粒平均尺寸在5nm左右。在制备过程中通过复合激光束辅以温度为金刚石薄膜的生长提供了更有利的条件,并在常温常压下连续制备出了粒度分布均匀的纳米金刚石薄膜。     

金刚石薄膜及其在红外末制导系统中的应用

本文介绍了金刚石薄膜独特、优异的性能和低压化学汽相沉积（ＣＶＤ）金刚石薄膜的研究进展情况，并且就金刚石薄膜在红外末制导系统中的应用进行了分析和探讨。     

用脉冲激光沉积法制备类金刚石膜及金刚石薄膜

简要评述了用脉冲激光沉积技术制备类金刚石膜及金刚石薄膜的研究进展，总结了激光脉冲沉积制备薄膜的基本原理及其特点，分析了激光波长，能量，衬底温度等对薄膜质量的影响。     

MPCVD金刚石薄膜的红外椭偏光学性能研究

椭圆偏振光谱法是一种非破坏性光谱技术。为了获得微波等离子体化学汽相沉积(MPCVD)金刚石薄膜的最佳沉积条件,用红外 椭圆偏振光谱仪对MPCVD金刚石薄膜的红外光学性能进行了表征测量,并分析了衬底温度和反应室的压强对金刚石 薄膜的红外光学性质的影响。当甲烷浓度不变,衬底温度为750℃,反应室的压强为4.0kPa时,金刚石膜的红外椭偏光学性质达到最 佳,其折射率的平均值为2.393。研究结果表明,金刚石薄膜的光学性能与薄膜质量密切相关,同时也获得了最佳的金刚石薄膜工艺 条件。     

微波等离子体沉积金刚石薄膜

结合自己的研究工作,介绍了微波等离子体沉积金刚石薄膜的优点及其应用;还介绍了美、英、苏等国利用微波等离子体沉积金刚石薄膜的最新动向。     

脉冲激光沉积类金刚石膜技术

脉冲激光沉积(PLD)技术制备类金刚石(DLC)薄膜存在着金刚石相含量较低、石墨颗粒多、薄膜与衬底附着力差、膜内应力大等技术难题,为此,研究人员研究出了多种技术措施,如通过引入背景气体、超快激光、偏压、磁场以及加热等措施提高了薄膜金刚石相含量;采用金刚石或丙酮靶材、减小单脉冲能量等措施减少了石墨颗粒;采用间歇沉积、真空退火、超快激光等措施减少了膜内应力;合理没计过渡层改善了膜与衬底间的附着力等.这些技术有力地推动了脉冲激光沉积技术的发展.     

铁电薄膜：理论与应用

本文评述了铁电薄膜的制备力法;对铁电薄膜的理论研究成果作了概括的讨论,重点讨论表面层与膜层内应力对薄膜铁电行为的影响;文中介绍了铁电薄膜在存储、发光、显示及探测等方面的应用;最后简要地指出了铁电薄膜的理论与应用研究的前景。     

Scalable 3D Self-Assembly of MXene Films for Flexible Sandwich and Microsized Supercapacitors

The self-assembly of large-area MXene films is the main step to realize their applications in various energy storage devices. However, the scalable self-assembly of flexible thin MXene films with high conductivity as well as excellent mechanical and electrochemical properties is still a challenge. Herein, a synchronous reduction and self-assembly strategy to fabricate flexible MXene films is developed, where MXene films are synchronously reduced and self-assembled on the Zn foil surface. Furthermore, the self-assembly of MXene films can be scaled up by controlling the area of Zn substrates. By adjusting the patterns of Zn substrates, the interdigital MXene patterns can also be obtained via a selectively reducing/assembling process. The resultant MXene films demonstrate high electrical conductivity, large specific surface area, and excellent mechanical properties. Thus they can serve as the electrodes of flexible supercapacitor devices directly. As a proof of concept, flexible sandwich and microsized supercapacitors are designed based on the above MXene film electrodes. Both sandwich and microsized supercapacitors display stable electrochemical performance under various bending states. This study provides a route to achieve large-area MXene-based films or microsized structures for applications in the field of energy storage.     

Low-temperature growth of RuO2 films for conductive electrode applications

Conductive ruthenium oxide films are considered as possible candidate for electrodes in complementary metal oxide semiconductor and random-access memory applications. We have succeeded in growth of highly conducting RuO₂ films by metal organic chemical vapour deposition on silicon substrates at deposition temperatures between 250°C and 500°C. Structural and electrical properties of the films were studied as a function of deposition temperature. Room temperature resistivity of the films increased from 40 μΩcm for the deposition temperature 500°C to above 100 μΩcm for the deposition temperature 250°C. The films prepared at temperatures below 300°C exhibit smooth surface and excellent step coverage. These films could be used in the above-mentioned applications.     

Silicon Nitride Films Deposited by RF Sputtering for Microstructure Fabrication in MEMS

In the present work, we report silicon nitride films deposited by a radio- frequency (RF) sputtering process at relatively low temperatures (<260°C) for microelectromechanical system (MEMS) applications. The films were prepared by RF diode sputtering using a 3-inch-diameter Si₃N₄ target in an argon ambient at 5 mTorr to 20 mTorr pressure and an RF power of 100 W to 300 W. The influence of the film deposition parameters, such as RF power and sputtering pressure, on deposition rate, Si-N bonding, surface roughness, etch rate, and stress in the films was investigated. The films were deposited on single/double-side polished silicon wafers and transparent fused-quartz substrates. To explore the RF-sputtered silicon nitride film as a structural material in MEMS, microcantilever beams of silicon nitride were fabricated by bulk, surface, and surface-bulk micromachining technology. An RF-sputtered phosphosilicate glass film was used as a sacrificial layer with RF-sputtered silicon nitride. Other applications of sputtered silicon nitride films, such as in the local oxidation of silicon (LOCOS) process, were also investigated.     

Excimer laser-assisted planarization of thick diamond films

The planarization of polycrystalline diamond films is critical for a large number of industrial applications. We have investigated a laser-assisted method for planarization of thick diamond films. This method is based on the application of excimer laser combined with simultaneous rotation of the sample. Thick diamond films (average surface roughness: ∼20 μm and thickness ∼500 μm) were fabricated by plasma jet chemical vapor deposition process. The planarization of diamond films was found to be critically dependent on the angle of incidence of laser beam. Smoother surfaces were obtained at higher incidence angles (θ = 80°). However, by combination of sample rotation with laser irradiation at higher incidence angles (θ = 80°), maximum surface planarization was achieved. Under optimum conditions, the surface roughness of the samples were reduced from 20 to 0.1 μm. The mechanisms for surface planarization of thick diamond films are discussed.     

Harnessing Surface Wrinkle Patterns in Soft Matter

Mechanical instabilities in soft materials, specifically wrinkling, have led to the formation of unique surface patterns for a wide range of applications that are related to surface topography and its dynamic tuning. In this progress report, two distinct approaches for wrinkle formation, including mechanical stretching/releasing of oxide/PDMS bilayers and swelling of hydrogel films confined on a rigid substrate with a depth‐wise modulus gradient, are discussed. The wrinkling mechanisms and transitions between different wrinkle patterns are studied. Strategies to control the wrinkle pattern order and characteristic wavelength are suggested, and some efforts in harnessing topographic tunability in elastomeric PDMS bilayer wrinkled films for various applications, including tunable adhesion, wetting, microfluidics, and microlens arrays, are highlighted. The report concludes with perspectives on the future directions in manipulation of pattern formation for complex structures, and potential new technological applications.     

Preparation of conductive flexible films by in situ deposition of polythiophene nanoparticles on polyethylene naphthalate

Deposition of Polythiophene (PTh) nanoparticles on the unmodified and modified polyethylene naphthalate (PEN) films via solution based in situ chemical polymerization was investigated as conducting transparent anode electrodes in order to produce transparent conducting films with applications in opto-electronic devices, such as flexible displays. The surface of PEN films were modified by different methods. Surface modification was carried out using Piranha and alkaline (KOH) solution and ultraviolet (UV) radiation as a physical method. Combination of chemical and physical treatments (Piranha and UV) was also examined. The effect of surface modification methods on the properties of the in situ deposited PTh nanoparticles was studied. It was found that electrical conductivity increases ~20 times in effect of modification of PEN by the examined methods. Highly ordered morphology of PTh nanoparticles were observed by field emission scanning electron microscope (FESEM) in the case of surface modification by UV radiation. Hydrophilicity, transparency and surface morphology of the PEN films were found to be influenced by surface modification techniques as well.     

Tunable Structural Color Surfaces with Visually Self‐Reporting Wettability

Functional materials with wettability of specific surfaces are important for many areas. Here, a new lubricant‐infused elastic inverse opal is presented with tunable and visually “self‐reporting” surface wettability. The elastic inverse opal films are used to lock in the infused lubricating fluid and construct slippery surfaces to repel droplets of various liquids. The films are stretchable, and the lubricating fluid can penetrate the pores under stretching, leaving the surface layer free of lubrication; the resultant undulating morphology of the inverse opal scaffold topography can reversibly pin droplets on the fluidic film rather than the solid substrate. This mechanical stimulation process provides an effective means of dynamically tuning the surface wettability and the optical transparency of the inverse opal films. In particular, as the adjustments are accompanied by simultaneous deformation of the periodic macroporous structure, the inverse opal films can self‐report on their surface status through visible structural color changes. These features make such slippery structural color materials highly versatile for use in diverse applications.     

Titanium Nitride Modified Photoluminescence from Single Semiconductor Nanoplatelets

Titanium nitride (TiN) is an alternative plasmonic material that has the potential for visible and near‐infrared optical applications due to its distinct properties. Here, coupling effects between TiN nanohole array films and nearby excitonic emitters, semiconductor nanoplatelets (NPLs), are investigated using single particle spectroscopy. At the emission wavelength of the NPLs, the local field enhancement close to the surface of the TiN nanohole array films induces an increase in the radiative decay rates of the emitters by a factor of up to 2. This effect diminishes quickly as the distance between the TiN nanohole array films and emitters increases. At short wavelengths where the NPLs are excited, the TiN nanohole array films exhibit lossy dielectric characteristics. Local field modification at these wavelengths leads to a reduced local density of electromagnetic states, and hence the photoluminescence intensity of the emitters. This study shows the potential of TiN as an alternative plasmonic material for optoelectronic and photonic applications, especially in the long wavelength ranges.     

Random Copolymer Films with Molecular‐Scale Compositional Heterogeneities that Interfere with Protein Adsorption

Smooth surfaces with compositional heterogeneities at a molecular‐length scale are presented with the goal of disrupting surface–protein interactions. These surfaces are synthesized by utilizing photoinitiated chemical vapor deposition (piCVD) to deposit thin films of random copolymers consisting of highly hydrophilic and highly hydrophobic comonomers. Swellability, wettability, and surface roughness could be systematically controlled by tuning the copolymer composition. The surface composition was dynamic, and the surface reconstructed based on the hydration state of the film. Proteins adsorbed to the copolymer films less readily than to either of the respective homopolymers, indicating a synergistic effect resulting from the random copolymer presenting molecular‐scale compositional heterogeneity. These results provide direct evidence that protein adsorption can be disrupted by such surfaces and a simple analytical model suggests that the heterogeneities occur over areas encompassing 4–5 repeat units of the polymer. The synthetic method used to create these films can be used to coat arbitrary geometries, enabling practical utility in a number of applications.