基于富勒烯液态源的超纳米晶金刚石薄膜生长

通过微波等离子体化学气相沉积技术(MWPCVD),以富勒烯(C60)甲苯饱和溶液为碳源,用载气携带的方式通入反应腔中生长金刚石膜。Raman光谱、SEM和AFM表征结果表明得到的超纳米晶金刚石薄膜相组成纯度较高,其平均晶粒尺寸约为15 nm,表面粗糙度为16.56 nm,薄膜平均生长速率约为0.6μm/h。此方法较其他以C60为碳源生长超纳米晶金刚石薄膜的方法更为简便,且容易控制富勒烯碳源的浓度,沉积速率更高,是一种新型的制备超纳米晶金刚石薄膜的可控工艺方法。     

低压气相沉积金刚石薄膜研究

低压气相沉积金刚石薄膜研究霍万库，李惠琪，李惠东（山东矿业学院）胡灼源，傅珍泰，刘福民（泰安市金属材料表面处理中心筹建处）金刚石是碳的一种同素异形体，人们很久以前就试图用石墨来直接制取金刚石。１９５５年，美国通用电器公司在世界上首次用高温高压方法成功...     

微波等离子体化学气相沉积工艺对透明金刚石膜质量的影响

在自制的２４５０ＭＨｚ／５ｋＷ不锈钢谐振空型微波等离子体学气相沉积装置中研究了基片预处理和工艺参数对微波等离子体化学气相沉积金刚石膜质量的影响,研究了提高成核密度和沉积速率的方法,用ＳＥＭ,ＸＲＤ,ＦＴＩＲ,Ｒａｍａｎ和ＡＦＭ分析了金刚石膜的质量,结果表明：用纳米金刚石粉研磨单晶基片,在沉积气压６．０ｋＰａ,ＣＨ４／Ｈ２的体积流量比为０．７５％时,可 出红外透光率达６８％,表面粗糙度为１１４．１０     

砷化镓上生长金刚石薄膜的研究

以CH4和H2为气源,用微波辅助等离子体装置,在10.0 mm×7.0 mm的砷化镓基底上沉积了CVD金刚石薄膜,用扫描电子显微镜观察沉积效果,拉曼光谱表征沉积质量,分析薄膜附着力与砷化镓材料性能的关系。结果表明,当基体温度为600℃,气压为5 kPa,甲烷浓度为2.0%时,在砷化镓片表面上沉积出了CVD金刚石薄膜,晶粒尺寸均匀,晶形完整、规则,晶界非常清晰。     

生长时间对纳米金刚石薄膜微结构的影响

文章研究了不同沉积时间下制备的不同厚度纳米金刚石薄膜的微观结构和相组成。采用热丝化学气相沉积法分别制备了沉积时间为52、67、97和127min的纳米金刚石薄膜。采用扫描电子显微镜和拉曼光谱表征薄膜的微观结构和相组成。结果表明,纳米金刚石薄膜表面颗粒尺寸大小无明显变化,约为50nm。随着生长时间增加,金刚石相含量保持稳定没有明显的增加或减小趋势,石墨相有序度以及石墨团簇尺寸随着生长时间增加而增加。     

CVD金刚石薄膜的制备方法及应用

对现在的化学气相沉积金刚石薄膜的方法和金刚石薄膜在器件中的应用进行介绍和评论。     

温度对直流热阴极化学气相沉积硼掺杂金刚石薄膜的影响(英文)

为了获得高品质的硼掺杂金刚石薄膜,采用直流热阴极化学气相沉积法在不同的温度下制备了硼掺杂金刚石薄膜。利用等离子体发射光谱、扫描电子显微镜、X射线衍射和Raman光谱研究了温度对硼掺杂金刚石薄膜生长特性的影响。研究发现:等离子体活性基团 C2的浓度随温度升高而增加。除了1080℃时生长的薄膜存在孔洞外,在较宽的温度范围(800～1000℃)都能够生长高质量的硼掺杂金刚石薄膜,并随温度升高薄膜质量和晶体结晶度都有所提高。与未掺杂生长的金刚石薄膜相比,掺硼薄膜即使在较低的温度(800℃)时也没有出现非金刚石相。这主要是因为掺杂剂B(OCH3)3 在气相反应中能够生成含氧活性基团,对非金刚石相具有很强的刻蚀作用。     

基于金属催化等离子体刻蚀的MPCVD单晶金刚石生长缺陷调控

单晶金刚石作为一种性能优异的半导体材料,在功率器件、深空探测等领域具有广阔的应用前景。然而采用微波等离子体化学气相沉积(MPCVD)法制备的单晶金刚石通常含有大量的缺陷,尤其是位错,严重限制了其电学性能的发挥。横向外延生长是半导体材料中常用的缺陷调控方法,近年也被应用于金刚石材料制备领域。本研究首先通过金属催化等离子体刻蚀在单晶金刚石籽晶上构造图形阵列,从而为同质外延单晶制备创造横向生长条件;随后通过MPCVD法在此基础上进行单晶金刚石制备,研究了横向外延生长过程并对样品进行了激光共聚焦显微镜、偏光显微镜、Raman光谱和缺陷密度测试。测试表明该方法能够稳定可控的制备图形化生长所需的阵列并降低生长层的缺陷密度。     

单晶金刚石膜与多晶金刚石膜的制备工艺及性能

本文主要介绍了用微波等离子体化学气相沉积法(以下简称MP CVD法)以甲醇-氢气混合气和丙酮-氢气混合气为源气体,分别以单晶硅的(111)面和人造金刚石的(100)面为衬底材料,制备出了面积为20mm×20mm厚为10μm的多晶金刚石膜和面积为1.0mm×1.0mm厚为5μm的单晶金刚石膜。通过试验发现,源气体配比和衬底温度对薄膜质量起决定性作用。另外,衬底在反应腔中的位置对薄膜的生成也有很大影响。单晶金刚石膜制备过程中衬底金刚石的晶体取向与金刚石薄膜的生长及质量有密切的关系。在金刚石的(100),(110)和(111)面上分别获得了单晶金刚石膜和金刚石多晶粒子。选用扫描电镜、显微激光拉曼、反射电子衍射对多晶金刚石膜及单晶金刚石膜的性能进行了测试。     

Formation of ultrananocrystalline diamond films with nitrogen addition

Nitrogen-doped ultrananocrystalline diamond (UNCD) films have been prepared by the microwave plasma jet chemical vapor deposition system (MPJCVD) using a gas mixture of Ar-1%CH₄-10%H₂ and addition of 0.5-7% nitrogen. This growth process by MPJCVD with 10% hydrogen addition that yields UNCD films compared with those UNCD films produced by MPCVD with a high Ar/CH₄ ratio due to the focused microwave plasma jet greatly enhanced the enough dissociation of react gases and formed C₂ species with an energetic state at lower argon concentration. The surface morphologies were changed drastically from continuous to rough granular surface with increasing the nitrogen content due to the great rise of CN species in the plasma. The width of grain boundaries composed of sp²-bonded carbon increased with increasing nitrogen content in the films. Moreover, the seldom defects in the UNCD films induced by the addition of nitrogen in the plasma were identified and investigated by using a scanning transmission electron microscope (STEM). The highest nitrogen-doped benefit with a N/C atomic ratio of 3.25% in UNCD films was reached by addition of only 3% N₂ in plasma (Ar-1%CH₄-10%H₂-3%N₂), showing the MPJCVD can greatly reduce the used amount of nitrogen in the synthesis of nitrogen-doped UNCD films.     

Effect of EDTA concentration on the physical and optical properties of Cds thin films

Application of ethylenediamine tetraacetic acid (EDTA) in the chemical bath solution to enhance the physical and optical properties of chemical bath deposited CdS film was realised. The observed beneficial effect on the crystallisation of CdS crystallites in the bath solution followed by deposition on glass substrates reduces the amorphousity and enhances the crystallinity of the film. The optical transparency of the film attains a maximum of 80% over the wavelength range of 650–1100 nm for the film deposited from EDTA‐added solution having the concentration of 0.006 mol/L. Also, the observed intensity of the characteristic photoluminescence emission was found to be dependent on the concentration of EDTA in the bath solution. © 2011 Canadian Society for Chemical Engineering     

Growth of faceted, ballas-like and nanocrystalline diamond films deposited in CH4/H2/Ar MPCVD

The influence of Ar addition to CH₄/H₂ plasma on the crystallinity, morphology and growth rate of the diamond films deposited in MPCVD was investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. X-Ray diffraction patterns indicate that diamond films of strong (111) and weak (400) texture are produced in these samples. Faceted diamond gradually turns into ballas-like diamond with graphitic inclusions when the Ar concentration increases to above 30 vol.%, as indicated by Raman spectra. As the Ar concentration goes above 90 vol.%, nanocrystalline diamond films are formed, characterized by a 1150-cm⁻¹ peak in the Raman spectra and morphology observation. Diamond growth by CH₃ or by C₂ mechanism is proposed to interpret the change in the growth rate of diamond films with the variation of Ar content in the plasma.     

High-quality homoepitaxial diamond (100) films grown under high-rate growth condition

We present advantages of high-power microwave plasma chemical vapor deposition (MPCVD) in homoepitaxial diamond film deposition. Diamond films grown at comparatively high growth rate of 3.5 μm/h showed intense free-exciton recombination emission at room temperature. The free-exciton decay time of the diamond film at room temperature, 22 ns, was much longer than that of type-IIa single crystal, indicating electronically high quality of the homoepitaxial films. Dislocation-related emissions were locally observed, a part of which created by mechanical polishing process was successfully removed by surface etching process using oxygen plasma. Another advantage of the high-power MPCVD is effective impurity doping; boron-doped diamond films with high carrier mobility and high carrier concentration were reproducibly deposited. An ultraviolet photodetector fabricated using the high-quality undoped diamond film showed lower noise equivalent power as well as higher photoresponsivity for ultraviolet light with better visible-blind property, compared to those of standard Si-based photodetectors. The high-power MPCVD is, thus, indispensable technique for depositing high quality diamond films for electronic devices.     

Initiated chemical vapor deposition of polyvinylpyrrolidone-based thin films

Initiated chemical vapor deposition (iCVD) is used for the first time to deposit a non-acrylic carbon-based polymer, polyvinylpyrrolidone (PVP). PVP is known for its hydrophilicity and biocompatibility, and its thin films have found many applications in the biomedical community, one of which is as antibiofouling surfaces. From vapors of 1-vinyl-2-pyrrolidone (VP) and tert-butyl peroxide (TBPO), iCVD produces PVP thin films that are spectroscopically identical to bulk PVP without using any solvents. iCVD works by selectively fragmenting gaseous TBPO with heat to create radicals for initiation of polymerization. This selectivity ensures that the monomer VP does not disintegrate to form species that do not conform to the structure of PVP. Fourier-transform infrared (FTIR), nuclear magnetic resonance, and X-ray photoelectron spectroscopy (XPS) show full retention of the hydrophilic pyrrolidone functional group. Number-average molecular weights range between 6570 and 10,200 g/mol. The addition of ethylene glycol diacrylate (EGDA) vapor to the reaction mixture creates a cross-linked copolymer between VP and EGDA. Films with different degrees of cross-linking can be made depending on the partial pressures of the species. Methods for quantifying the relative incorporation of VP and EGDA using FTIR and XPS are introduced. The film with the lowest degree of cross-linking has a wetting angle of 11°, affirming its high hydrophilicity and iCVD's ability to retain functionality.     

等离子体增强化学气相沉积法制备氢化硅膜的自晶化倾向性

为了探寻生长过程中硅膜的自晶化沉积,采用等离子体增强化学气相沉积(PECVD)法沉积了氢化硅薄膜,系统研究了不同沉积阶段所得硅膜微观结构的迁变规律。结果表明,硅膜的显微结构依赖于沉积时间,当沉积时间仅为30min时,所得硅膜的结构为非晶;而当沉积时间延至60min时,硅膜形成微晶颗粒;此后随着沉积时间的增加,晶化程度提高,且非晶区域面积相应减小。另外,硅膜的沉积速率也随沉积时间的增加而增加。在硅膜沉积过程中,随时间不断变化的界面状态可能为其自晶化的主要原因。     

Effect of N doping on properties of diamond-like carbon thin films produced by RF capacitively coupled chemical vapor deposition from different precursors

In this paper, we report results concerning properties of diamond-like carbon (DLC) thin films obtained in different experimental conditions: various RF power values and different precursors (methane, acetone and toluene or in combination with nitrogen). The deposition rate of DLC thin films obtained from precursors with low ionizing energy and high number of carbon atoms in molecule as acetone and toluene was higher (142 nm/min for acetone and 607 nm/min for toluene as compared with 79 nm/min for methane at 400 W input power). The highest value of hardness was obtained from methane (18 GPa). In the case of acetone and toluene precursors, the hardness increased with input power to the highest values of 16.8 and 14.8 GPa. By utilizing nitrogen as doping element, the resistivity of DLC thin films obtained from methane and acetone decreased from values higher than 10⁷ Ω cm to lower values of 12.5×10³ Ω cm for 3.79% nitrogen atomic concentration in the case of films obtained from methane and 40×10³ Ω cm for 4.26% nitrogen atomic concentration in the case of films obtained from acetone.     

Effect of annealing on SiC thin films prepared by pulsed laser deposition

Crystalline cubic SiC thin films were successfully fabricated on Si(100) substrates by using laser deposition combined with a vacuum annealing process. The effect of annealing conditions on the structure of the thin films was investigated by X-ray diffraction and Fourier transform infrared spectroscopy. It was demonstrated that amorphous SiC films deposited at 800°C could be transformed into crystalline phase after being annealed in a vacuum and that the annealing temperature played an important role in this transformation, with an optimum annealing temperature of 980°C. Results of X-ray photoelectron spectroscopy revealed the approximate stoichiometry of the SiC films. The characteristic microstructure displayed in a scanning electron microscope image of the films was indicative of epitaxial growth along the (100) plane.