一氧化碳合成金刚石薄膜的形貌和结构分析

利用微波等离子体化学气相沉积(MPCVD)技术，采用偏压增加成核(BEN)、两步生长的方法在一氧化碳(CO)和氢气(H₂)的环境下制备了金刚石薄膜. 利用扫描电子显微镜(SEM)、Raman光谱仪和透射电子显微镜(TEM)对金刚石薄膜的形貌和结构进行了分析. 研究发现金刚石晶粒在第一步成核及生长的过程中产生了层错和孪晶，而在第二步的生长过程中产生的层错和孪晶很少，最终形成的金刚石晶粒外表面比较光滑，包含有近五次对称或者平行的片状的孪晶，并可以观察到少量的位错. 而在样品的边缘由于等离子体的不均匀产生了比样品中心成核密度低的区域. 在这个区域中，发现了一个新的非金刚石的碳结构.     

织构金刚石薄膜的成核与生长

在加衬底偏压和不加衬底偏压两种情况下，用微波等离子体化学汽相沉积（MWCVD）技术在Ｓｉ（１００）衬底上合成了织构的金刚石薄膜使用扫描电子显微镜（ＳＥＭ）和取向Ｘ射线衍射技术证实了我们得到的样品是织构的金刚石薄膜观察了织构的金刚石薄膜的成核和生长过程，从理论上对金刚石薄膜异质外延的成核和生长机理进行了探讨 关键词：     

石英衬底上生长的高光学质量的纳米金刚石薄膜

采用射频等离子体增强的热丝化学气相沉积(RFHFCVD)技术在石英玻璃衬底上制备了表面光滑、晶粒致密均匀的纳米金刚石薄膜.用扫描电子显微镜(SEM)和台阶仪观测薄膜的表面形貌和粗糙度,x射线衍射(XRD)和Raman光谱表征膜层的结构,并用紫外可见近红外光谱仪测量其光透过率.实验结果表明,衬底温度、反应气压及射频功率对金刚石膜的结晶习性、表面粗糙度及光透过率均有很大程度的影响,其最佳值分别为700℃,2×133Pa和200W.在该最佳参量下经1h的生长即获得连续、平滑的纳米金刚石膜,其平均晶粒尺寸为约25 关键词： 纳米金刚石薄膜 射频等离子体增强热丝化学气相沉积 光透过率     

硅基籽晶上化学气相沉积金刚石薄膜及其场发射特性

通过控制电泳沉积(EPD)时间,在硅基片上沉积不同密度的金刚石籽晶。再用热丝化学气相沉积(HFCVD)设备,在硅基籽晶上合成多晶金刚石薄膜。薄膜中通常含有非金刚石相碳成分。用扫描电子显微镜(SEM)和Raman光谱对样品的表面形貌和成分进行了表征,测量了样品的场发射特性。比较并分析了样品的表面形貌和非金刚石成分上的差异对金刚石薄膜场发射特性的影响。     

高质量宽带隙立方氮化硼薄膜的研究进展

文章着重介绍了最近研制出的高质量宽带隙立方氮化硼薄膜的三种制备方法和结构特性 :(1)用射频溅射法在Si衬底上制备出立方相含量在 90 %以上 ,Eg>6 .0eV的c-BN薄膜 ;(2 )用离子束辅助的化学气相沉积法(CVD) ,在金刚石上外延生长出立方含量达 10 0 %的单晶c -BN薄膜 ;(3)用微波电子回旋共振CVD法 (MW -ECR-CVD)在金刚石上外延生长出高纯c-BN薄膜 .这些高纯c -BN薄膜 ,可应用于制作各种半导体 (主要是高温、高频大功率 )电子器件 .     

脉冲偏压电弧离子镀C-N-V薄膜的成分、结构与性能

用脉冲偏压电弧离子镀方法在硬质合金基体上制备了一系列不同成分的C-N-V薄膜.用X射线光电子能谱、激光Raman光谱、 X射线衍射(XRD)、透射电子显微镜(TEM)和纳米压痕等方法分别研究了薄膜的成分、结构与性能.Raman光谱,XRD和TEM结果表明,所制备的薄膜为在类金刚石(DLC)非晶基体上匹配有VN晶体的碳基复合薄膜.随V和N含量的增加,薄膜硬度与弹性模量先增加后下降,在N含量为204%,V含量为218%时薄膜硬度与弹性模量具有最大值,分别为368和5697 GPa,高于相同条件下制备的 关键词： C-N-V薄膜 类金刚石薄膜 纳米复合薄膜 电弧离子镀     

电子助进热丝化学汽相沉积金刚石薄膜

以CH₄和H₂为源反应气体，利用电子助进热丝化学汽相沉积（CVD）技术，在Si（100）晶面衬底上成功地得到了织构生长的金刚石薄膜．用扫描电子显微镜、Raman光谱、X射线衍射等多种技术对薄膜的形貌、成分、晶态等特性进行了分析，得到了在热丝CVD实验条件下织构生长金刚石薄膜的最佳工艺条件． 关键词：     

含氢碳膜的生长机制: 分子动力学模拟研究低能量CH基团的作用

探索等离子增强化学气相沉积(PECVD)技术中含氢碳膜的生长机理, 制备出常态超润滑含氢碳膜是表面工程技术领域的目标之一. 基于REBO势函数, 采用分子动力学模拟方法, 通过对比研究CH基团在清洁金刚石和吸氢金刚石表面的沉积行为, 发现低能量CH基团在清洁金刚石(111)面上的吸附效率大于98%, 而在吸氢金刚石(111)面上的吸附效率低于1%. 结果表明PECVD法制备含氢碳膜时, 低能量CH基团对薄膜生长的贡献主要来自于其在表面非饱和C位置的选择性吸附.     

CH基团与金刚石(111)面的碰撞反应及其对碳膜生长的影响

等离子体增强化学气相沉积技术中的碳膜选择性自组装机理是高性能碳膜制备过程中的挑战性基础课题.采用经典分子动力学方法,模拟了不同能量(1.625-65 eV)的CH基团在清洁金刚石和吸氢金刚石(111)面上的轰击行为,获得了吸附、反弹、反应等各类事件的发生概率,并据此探讨了含氢碳膜制备过程中CH基团的贡献.结果表明,随着入射能量的增加,CH基团对薄膜生长的贡献由单纯的吸附、反弹机理向反应、吸附混合机理转变,其中最主要的反应过程是释放一个或两个氢原子的反应,而释放氢分子的反应则很少发生.这些反应不仅使薄膜生长过程更均匀、薄膜表面更平整,还降低了薄膜的氢含量.生长机理的转变导致低能量条件下所成薄膜中的多数碳原子都包含一个氢原子作为配位原子,而高能量条件下的薄膜中的碳原子则很少有氢原子作为配位原子.另外,通过分析sp~3-C和sp~2-C数目的变化,研究了CH基团对金刚石基底的破坏作用.     

铜合金薄膜高温行为的电子显微镜观察

本文研究了在碳基上的铜合金蒸发薄膜的高温行为。用TEM和HVEM的加热台进行了观察并录像。Cu,Cu-Ti和Cu-Sn-Ti薄膜在分别加热到约640,700,750℃时,晶粒的衍射衬度开始迅速变化。在分别加热到约660,750,800℃时薄膜中空洞迅速扩展,最后形成孤立的小岛。扫描电子显微镜下观察到在石墨和金刚石基底上的薄膜加热到750—850℃时产生球化。在金刚石(100)和(111)面球化的不同形貌可以认为是由于浸润性的不同。用不同曲率下表面扩散的模型对薄膜中空洞的扩展速率进行了计算,得到与实验值数量级一致的结果。 关键词：     

The comparison between CdS thin films grown on Si(111) substrate and quartz substrate by femtosecond pulsed laser deposition

Two kinds of cadmium sulfate (CdS) thin films have been grown at 600 °C onto Si(111) and quartz substrates using femtosecond pulsed laser deposition (PLD). The influence of substrates on the structural and optical properties of the CdS thin films grown by femtosecond pulsed laser deposition have been studied. The CdS thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), photoluminescence (PL) and Raman spectroscopy. Although CdS thin films deposited both on Si(111) and quartz substrates were polycrystalline and hexagonal as shown by the XRD , SEM and AFM results, the crystalline quality and optical properties were found to be different. The size of the grains for the CdS thin film grown on Si(111) substrate were observed to be larger than that of the CdS thin film grown on quartz substrate, and there is more microcrystalline perpendicularity of c-axis for the film deposited on the quartz substrate than that for the films deposited on the Si substrate. In addition, in the PL spectra, the excitonic peak is more intense and resolved for CdS film deposited on quartz than that for the CdS film deposited on Si(111) substrate. The LO and TO Raman peaks in the CdS films grown on Si(111) substrate and quartz substrate are different, which is due to higher stress and bigger grain size in the CdS film grown on Si(111) substrate, than that of the CdS film grown on the amorphous quartz substrate. All this suggests that the substrates have a significant effect on the structural and optical properties of thin CdS films. PACS 81.15.Fg; 81.05.Ea; 78.20.-e; 78.67.-n; 42.62.-b     

Efficient field emission from well-oriented Cu2O film

Well-oriented Cu₂O films comprising of octahedral-shaped crystals were grown directly on copper foil via an hydrothermal treatment. The well-oriented films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Field emission from the film showed good emission properties, and, the electron emission turn-on field (E_to) and threshold field (E_thr) are about 9.6 and 13.4 V/μm respectively, which is similar to the values reported for CuO nanofiber, although the latter has a much larger size. The corresponding Fowler-Nordheim (F-N) plots showed a linear behavior. The sharp corners of the tips are considered as main electron emitters and account for its good performance.     

Optical, structural and optoelectronic properties of pulsed laser deposition PbS thin film

Lead sulfide (PbS) nano-structured film has been grown on quartz substrates by the PLD technique. The deposited films were characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Formation of cubic phase of PbS nanocrystals is proven. The absorption and emission spectra were measured for different thicknesses of the films. I–V characteristics and photoconductivity of the deposited film were also measured. The results indicate an efficient performance of the deposited films as an optical detector.     

两步化学沉积法制备ZnO薄膜及其场发射特性

在低温常压条件下,以ITO玻璃为衬底,采用电化学法与湿化学法结合的两步化学沉积法制备了团簇状ZnO薄膜。利用XRD,SEM分析了薄膜结构和表面形貌,并采用二极管结构在高真空条件下对薄膜进行了场发射性能测试。稳定发射后,开启电场为3.0 V/μm。当电场为5.8 V/μm时,电流密度为583.3 μA/cm²。研究表明:两步化学沉积法低温制备ZnO薄膜是可行的,且该薄膜具有良好的场发射性能。     

Scalable synthesis of graphene on single crystal Ir(111) films

We have investigated single crystal Ir(111) films grown heteroepitaxially on Si(111) wafers with yttria-stabilized zirconia (YSZ) buffer layers as possible substrates for an up-scalable synthesis of graphene. Graphene was grown by chemical vapor deposition (CVD) of ethylene. As surface analytical techniques we have used scanning tunneling microscopy (STM), low-energy electron diffraction, scanning electron microscopy, and atomic force microscopy. The mosaic spread of the metal films was below 0.2° similar to or even below that of standard Ir bulk single crystals, and the films were basically twin-free. The film surfaces could be improved by annealing so that they attained the perfection of bulk single crystals. Depending on the CVD conditions a lattice-aligned graphene layer or a film consisting of different rotational domains were obtained. STM data of the non-rotated phase and of the phases rotated by 14° and 19° were acquired. The quality of the graphene was comparable to graphene grown on bulk Ir(111) single crystals.     

气相输运法制备ZnO薄膜(英文)

运用气相输运技术在不同的衬底上制备ZnO薄膜,同时对这些ZnO薄膜的表面形貌、晶体结构和光学特性进行表征。在扫描电子显微镜图像上可以看到,相比没有镀金的Si衬底,ZnO纳米颗粒在镀金的Si衬底上的生长尺寸较大。X射线衍射测试结果表明,在Si(111)和Si(100)衬底上生长的ZnO薄膜显示出不同的六角纤锌矿结构的衍射峰,但没有出现立方闪锌矿ZnO结构的衍射峰。在镀金的Si衬底上,ZnO薄膜生长取向主要为c轴方向。此外,所有ZnO样品的光致发光谱上均只出现一个狭窄且强的紫外峰,约在389 nm(3.19 eV)波长处。     

Columnar growth of crystalline silicon films on aluminium-coated glass by inductively coupled plasma CVD at room temperature

Silicon films were grown on aluminium-coated glass by inductively coupled plasma CVD at room temperature using a mixture of SiH₄ and H₂ as the source gas. The microstructure of the films was evaluated using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. It was found that the films are composed of columnar grains and their surfaces show a random and uniform distribution of silicon nanocones. Such a microstructure is highly advantageous to the application of the films in solar cells and electron emission devices. Field electron emission measurement of the films demonstrated that the threshold field strength is as low as ～9.8V/μm and the electron emission characteristic is reproducible. In addition, a mechanism is suggested for the columnar growth of crystalline silicon films on aluminium-coated glass at room temperature.     

Temperature-dependent photoluminescence spectra of GaN epitaxial layer grown on Si(111) substrate

In this paper, the temperature-dependent photoluminescence(PL) properties of Ga N grown on Si(111) substrate are studied. The main emission peaks of Ga N films grown on Si(111) are investigated and compared with those grown on sapphire substrates. The positions of free and bound exciton luminescence peaks, i.e., FX A and D0 X peaks, of Ga N films grown on Si(111) substrates undergo red shifts compared with those grown on sapphire. This is attributed to the fact that the Ga N films grown on sapphire are under the action of compressive stress, while those grown on Si(111) substrate are subjected to tensile stress. Furthermore, the positions of these peaks may be additionally shifted due to different stress conditions in the real sample growth. The emission peaks due to stacking faults are found in Ga N films grown on Si(111) and an S-shaped temperature dependence of PL spectra can be observed, owing to the influence of the quantum well(QW) emission by the localized states near the conduction band gap edge and the temperature-dependent distribution of the photo-generated carriers.     

Efficient field emission from coiled carbon nano/microfiber on copper substrate by dc-PECVD

Crystalline coiled carbon nano/micro fibers in thin film form have been synthesized via direct current plasma enhanced chemical vapor deposition (PECVD) on copper substrates with acetylene as a carbon precursor at 10 mbar pressure and 750 °C substrate temperature. The as-prepared samples were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). XRD pattern as well as selected area electron diffraction (SAED) pattern showed that the samples were crystalline in nature. SEM and HRTEM studies showed that as synthesized coiled carbon fibers are having average diameter ∼100 nm and are several micrometers in length. The as-prepared samples showed moderately good electron field emission properties with a turn-on field as low as 1.96 V/μm for an inter-electrode distance 220 μm. The variation of field emission properties with inter-electrode distance has been studied in detail. The field emission properties of the coiled carbon fibrous thin films are compared with that of crystalline multiwalled carbon nanotubes and other carbon nanostructures.     

Structural and cathodoluminescence assessment of transition metal oxide nanostructures grown by thermal deposition methods

Nanostructures of two transition metal oxides, WO₃ and α-Fe₂O₃, have been grown by a thermal deposition method without a catalyst and characterized by x-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy and cathodoluminescence (CL) in the SEM. WO₃ micro and nanorods exhibit CL emission two orders of magnitude higher than CL intensity from the untreated oxide. α-Fe₂O₃ nanostructures with different morphologies (wires, belts, rods, urchins) were grown at different temperatures on Fe substrates. CL spectra of these nanostructures show emission bands related to charge transfer and ligand field transitions.