High sp~3 content hydrogen-free amorphous diamond: an excellent electron field emission material

Details are given of a study of the characteristics of field-induced electron emission from hydrogen-free high sp~3 content (>90 % ) amorphous diamond (a-D) film deposited on heavily doped (p<0.01 Ω·cm) n-type monoerystalline Si (111 ) substrate. It is demonstrated that a-D film has excellent electron field emission properties. The emission current can reach 0.9 μA at applied field as low as 1 V/μm, and the emission current density can be ahout several mA/cm~2 under 20 V/μm. The emission current is stable when the beginning current is at 50 μA within 72 h. Uniform fluorescence display of electron emission from the whole face of the a-D film under the electric field of 10-12 V/μm is also observed. The contribution of excellent electron emission property results from the smooth, uniform, amorphous surface and high sp~3 content of the a-D film.     

High sp3 content hydrogen-free amorphous diamond: an excellent electron field emission material

Details are given of a study of the characteristics of field-induced electron emission from hydrogen-free high sp³ content (>90%) amorphous diamond (a-D) film deposited on heavily doped (ρ<0.01ω·cm) n-type monocrystalline Si (111) substrate. It is demonstrated that a-D film has excellent electron field emission properties. The emission current can reach 0.9 μA at applied field as low as 1 V/μm, and the emission current density can be about several mA/cm² under 20 V/μm. The emission current is stable when the beginning current is at 50 μA within 72 h. Uniform fluorescence display of electron emission from the whole face of the a-D film under the electric field of 10–12 V/μm is also observed. The contribution of excellent electron emission property results from the smooth, uniform, amorphous surface and high sp³ content of the a-D film. Project supported by the National High-Tech Program of China.     

Research on the preparation of amorphous diamond nanorod arrays and their excellent field emitting properties

During recent years, with the rapid development of IT and micro-electrics, the ultra- thin, ultra-large display screen with low power consumption, has attracted more and more attention. As the core of devices, cathode materials are made much more demands in the vacuum microelectronic technology. So the materials with low power consumption, outstanding field emission properties and extreme stability are very important. To resolve the problem, many researchers have been making efforts. Diamonds…     

Relationship between the orientation of texture and heteroepitaxy of diamond and related materials films on silicon single crystal and the valence electron structure of the interface

Diamond and cubic boron nitride films have already been applied practically because of their excellent properties. The specific orientations of the films have special meaning on their application in optics and microelectronics fields. In this paper, the relative electron density differences of the interface between the different crystal planes of silicon substrate and those of diamond and cubic boron films are calculated with the empirical electron theory in solids and molecules. Analyses on the calculation results show that in the range of the researched films, the smaller the relative electron density difference between the film and the substrate is, the stabler the film is in thermodynamics. Therefore, the electron density difference is the essential factor of determining the orientation of the texture and heteroepitaxy of the films. The deductions accord well with the experimental facts. The calculation methods and the theory not only provide a new angle of view for the research of the growth mechanism of diamond film and cubic boron nitride film on the silicon substrate, but also provide a possible direction for the prediction of the orientation of other films. Supported by the Research Project of the Ministry of Education of China (Grant No. 02018) and the Beijing Natural Science Foundation (Grant No. 2072014)     

纳米针状金刚石膜的制备

利用高功率微波等离子体化学气相沉积方法在硅衬底上沉积了多晶金刚石薄膜,然后利用电子束蒸发方法在金刚石薄膜表面上沉积了5 nm厚的Pt薄膜.利用Pt的自组织化效应,再通过氢等离子体照射、氧等离子体刻蚀、王水处理等手段,使金刚石薄膜表面形成了纳米针.利用拉曼光谱和扫描电子显微镜(SEM)表征金刚石薄膜的结构,拉曼光谱显示在1 315 cm^-1处出现纳米金刚石特征峰,SEM显示纳米针均匀地直立在金刚石薄膜表面,每平方厘米大约含有10⁸个纳米针,纳米针的平均高度约为1 μm.     

Structural and mechanical properties of amorphous carbon films deposited by the dual plasma technique

Direct current metal filtered cathodic vacuum are (FCVA) and acetylene gas (C2H2) were wielded to synthesize Ti-containing amorphous carbon films on Si (100). The influence of substrate bias voltage and acetylene gas on the microstructure and mechanical properties of the films were investigated. The results show that the phase of TiC in the (111) preferential crystallo-graphic orientation exists in the film, and rite main existing pattern of carbon is sp2. With increasing the acetylene flow rate, the con-tents of Ti and TiC phase of the film gradually reduce; however, the thickness of the film increases. When the substrate bias voltage reaches -600 V, the internal stress of the film reaches 1.6 GPa. The micro-hardness and elastic modulus of the film can reach 33.9 and 237.6 GPa, respectively, and the friction coefficient of the film is 0.25.     

基底偏压对BN薄膜场发射特性的影响

利用射频磁控溅射方法，在n型(100)Si基底上沉积了氮化硼薄膜(BN)．通过分析电流密度-电场强度曲线，发现BN薄膜的场发射特性与基底偏压影响很大，基底偏压为-140V时BN薄膜样品场发射特性要好于其它样品，阈值电场低于8V／μm．F-N曲线表明：电子是通过隧道效应克服BN薄膜表面势垒发射到真空的．     

WC—Co硬质合金上高质量金刚石薄膜的制备

采用微波等离子体化学气相沉积法在硬质合金基体上制备金刚石薄膜,研究了铜过渡层和酸蚀脱钴两种基体前处理工艺以及在施加铜过渡层的情况下,不同的沉积气压和基片温度对金刚石薄膜的质量的影响。结果表明,在施加铜过渡层后,在适中的沉积条件下（沉积气压6．0kPa,基片温度约为780度）可得到质量较好的金刚石薄膜。     

工作气压对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法，在n型(100)Si基底上沉积了氮化硼(BN)薄膜，并在超高真空系统中测量了BN薄膜的场发射特性．研究发现，沉积时工作气压的变化对BN薄膜的场发射特性有很大影响，工作气压为2Pa时沉积的BN薄膜样品的场发射特性较好，其阈值电场为6V/μm，场发射电流为320μA／cm^2．F—N曲线表明，在外加电场的作用下，电子是通过隧道效应穿透BN薄膜表面势垒发射到真空的．     

新型金刚石薄膜场电子发射的特性

介绍了用微波CVD法制备的一种新型低阈值电压大电流密度金刚石薄膜场发射冷阴极,阈值电压低于1.09 V/μm,场发射电流密度高达418 mA/cm²,这是目前文献中报道的最好结果之一.文中还探讨了金刚石薄膜场电子发射机制.     

基片温度对纳米金刚石薄膜掺硼的影响

采用微波等离子体化学气相沉积法,以氢气稀释的乙硼烷为硼源进行了纳米金刚石(NCD)薄膜的生长过程掺硼,研究了基片温度对掺硼NCD薄膜晶粒尺寸、表面粗糙度、表面电阻和硼原子浓度的影响.利用扫描电子显微镜和原子力显微镜观察NCD薄膜的表面形貌,并通过Imager软件对原子力显微镜数据进行分析获得薄膜的表面粗糙度及平均晶粒尺寸信息;采用四探针测量掺硼NCD薄膜的表面方块电阻,利用二次离子质谱仪对掺杂后NCD薄膜表面区域的硼原子浓度进行测量.实验结果表明,较高的基片温度有利于提高薄膜的导电能力,但随着基片温度的提高,NCD薄膜的平均晶粒尺寸和表面粗糙度逐渐增大;此外,当反应气体中的乙硼烷浓度一定时,掺杂后NCD薄膜的表面硼原子浓度随基片温度升高存在一个饱和值.在所选乙硼烷浓度为0.01%的条件下,基片温度在700℃左右可以在保证薄膜表面电性能的基础上保持较好的表面形貌.     

Fine structure and interface structure of ion-bombardment nitrided layers

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Preparation and characterization of nano-crystalline diamond films on glass substrate

Adherent nano diamond films were successfully deposited on glass substrate by microwave plasma assisted CVD method in H2-CH4 and Ar-CH4 environment. Raman, AFM (Atomic Force Microscope), TEM (Transmission Electron Microscope), FTIR, and Nano Indentation techniques were used for characterization of the obtained nano diamond films. It was found that the average grain size was less than 100 nm with a surface roughness value as low as 2 nm. The nano diamond films were found to have excellent transparency in visible and IR spectrum range, and were as hard as natural diamond. Experimental results were presented. Mechanisms for nano diamond film deposition were discussed.     

退火处理对Ti-Zr-Cu-Be块体非晶合金力学性能的影响

采用铜模铸造法制备了直径为2mm的Ti55-xZr10+xBe27.5Cu7.5(x=0,10,20)块体非晶合金,并对其进行等温退火处理.利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)及压缩试验等方法研究了非晶合金的相结构、显微组织和热稳定性,以及退火处理对其力学性能的影响.结果表明:该系列合金在553 K及583 K下保温长达5 h时间内依然表现为非晶态.退火处理后,Ti35Zr30Be27.5Cu7.5合金屈服强度、断裂强度均提到了提高,其中在583 K下保温1 h后屈服强度、断裂强度分别达到了1 921、2 169 MPa;其塑性由处理前的3.47%提高到了6.57%.Ti45Zr20Be27.5Cu7.5合金在退火后其力学性能变化不明显.Ti55Zr10Be27.5Cu7.5合金随着退火温度及保温时间的增加其屈服强度、断裂强度及塑性均明显降低.     

金刚石薄膜场发射述评

介绍了金刚石薄膜的场发射机理,从理论和实验上分析了改进其场发射特性的观点和方法,结果证明:减小金刚石晶体尺寸以及在金刚石薄膜中掺杂一定量的杂质原子有助于改善金刚石薄膜的场发射性能.     

采用Cu／Ti过渡层沉积金刚石薄膜刀具的界面结构

研究了硬质合金基底上Cu／Ti作过渡层化学气相沉积(CVD)金刚石薄膜的界面特性。利用激光Ra—man谱分析了过渡层不同生长阶段金刚石薄膜的质量的影响。采用SEM、EDS对金刚石薄膜硬质合金刀具横截面的结构进行了研究。结果表明：基体中的Co被Cu／Ti作过渡层有效的抑制住；Cu向基体内的扩散改善了基体的性能，提高了界面层金刚石薄膜的质量；Ti的引入促进了金刚石的形核，减少了界面处晶粒间的空隙，提高了金刚石薄膜与基体表面的实际接触面积。     

Simple method to rapidly fabricate chain-like carbon nanotube films and its field emission properties

A simple process to fabricate chain-like carbon nanotube (COT) films by microwave plasma-enhanced chemical vapor deposition (MPCVD) was developed successfully. Prior to deposition, the Ti/Al2O3 substrates were ground with Fe-doped SiO2 powder. The nano-structure of the deposited films was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The field electron emission characteristics of the chain-like carbon nanotube films were measured under the vacuum of 10-5 Pa. The low turn-on field of 0.80 V/μm and the emission current density of 8.5 mA/cm2 at the electric field of 3.0 Vμ/m are obtained. Based on the above results, chain-like carbon nanotube films probably have important applications in cold cathode materials and electrode materials.     

基片温度对金刚石厚膜生长的影响

采用微波等离子体化学气相沉积（MPCVD）法制备了Ф60mm的金刚石厚膜,通过对沉积过程和结果的观察发现,由于所用沉积气压较高,基片不同区域温度不均匀,导致不同区域沉积的金刚石厚膜晶型差距较大．通过对不同区域的结果进行比较,发现850℃为较好的沉积温度,并在对沉积工艺进行优化后,采用该温度在Ф60mm的基片上制备了厚度为0．6mm取向性很好的金刚石厚膜．     

Influence of bath composition on the electrodeposition of cobalt-molybdenum amorphous alloy thin films

Cobalt-molybdenum (Co-Mo) amorphous alloy thin films were deposited on copper substrates by the electrochemical method at pH 4.0. Among the experimental electrodeposition parameters, only the concentration ratio of molybdate to cobalt ions ([ MoO2-4 ]/[CO2 ]) was varied to analyze its influence on the mechanism of induced cobalt-molybdenum codeposition. Voltammetry was one of the main techniques, which was used to examine the voltammetric response, revealing that cobalt-molybdenum codeposi-tion depended on the nature of the species in solution. To correlate the type of the film to the electrochemical response, various co-bait-molybdenum alloy thin films obtained from different [ MoO2-4]/[Co2 ] solutions were tested. Crack-free homogeneous films could be easily obtained from the low molybdate concentrations ([ MoO2-4]/[Co2 ]≈0.05) applying low deposition potentials.Moreover, the content of molybdenum up to 30wt% could be obtained from high molybdate concentration; in this case, the films showed cracks. The formation of these cracked films could be predicted from the observed distortions in the curves of electric cur-rent-time (j-t) deposition transients. The films with amorphous stmeture were obtained. The hysteresis loops suggested that the easily film were obtained when the deposition potential was -1025 mV, and [ MoO2-4]/[Co2 ] was 0.05 in solution, which exhibited a nicer soft-magnetic response.