多腔耦合微波表面波PECVD法沉积DLC薄膜研究

报道了利用多腔耦合微波表面波等离子体增强化学气相沉积(PECVD)的方法制备类金刚石(DLC)薄膜。通过发射光谱(OES)测量,对Ar等离子体中的各种放电参数以及全部四个腔室内放电的均匀性作出评估。采用表面轮廓仪测量了薄膜的厚度;薄膜的表面形貌、组成结构通过原子力显微镜(AFM)、激光拉曼光谱和X射线衍射光谱(XPS)进行了表征。在12.5μm厚度的有机薄膜聚酯(PET)表面沉积一定厚度DLC后,通过测量水蒸气透过率(WVTR)对DLC薄膜的阻隔性能进行了研究。结果表明,这种多腔耦合微波表面波等离子体装置,不仅能够实现四个腔室同时相对均匀的放电,也能够实现单个腔室的轴向均匀放电。制备的DLC薄膜结构致密、成分均匀,可以使PET薄膜阻隔性能提高约20倍。     

丙酮环境下ECR微波等离子体辅助化学气相沉积类金刚石薄膜研究

利用电子回旋共振（ECR）微波等离子体辅助化学气相沉积技术、工作气氛为丙酮，在光学玻璃衬底上得到了光滑、致密、均匀的类金刚石薄膜.在工艺研究中，对等离子体中氧的存在及其作用进行了分析.原子力显微镜分析表明，薄膜的表面粗糙度小于10nm，晶粒 尺寸约为100nm.拉曼光谱和中红吸收谱研究发现，薄膜具有强烈的荧光效应，含有sp1，sp2，sp3杂化C—C，sp3杂化CH3，羰基CO、含氧多元 环以及—COOH基等.利用纳米力学探针以 及近红区红外透射谱分析了薄膜的力学及光学性能，结果表明，薄膜的显微硬度接近4 关键词： 类金刚石薄膜 ECR微波等离子体 丙酮气氛 红外光谱     

微波等离子体化学气相沉积金刚石薄膜形貌分析

 本文给出了微波等离子体化学气相沉积多晶金刚石薄膜及外延单晶金刚石薄膜的各种形貌，并对这些形貌的形成作了理论分析。     

低温等离子体沉积类金刚石薄膜

一、引 言 类金刚石薄膜有很多优越的性质,除了化学惰性外,它还具有很好的电学、光学和机械性能,如电阻率高,可见,紫外和红外光的透射性好以及附着力强等。至今已有各种各样的制备类金刚石的方法。如热解、离子束、溅射和等离子体化学气相沉积(PCVD)等。 本文采用的方法是在热丝CVD中加入直流放电。由于把直流放电和热解化学的方法结合起来,增强了CH_4的分解,同时为了了解成膜的微观过程,采用等离子体参数的诊断方法,实地监测膜的生成过程,对实现具有一定性质的类金刚石膜的重复生长是有利的。     

脉冲激光制备类金刚石薄膜及原位激光等离子体发射光谱

用ＹＡＧ脉冲激光轰击真空室内的石墨靶,可以形成包含碳素的激光等离子体,并在硅或石英衬氏上淀积形成某种类型的碳膜。用光学多道分析仪原位测量了激光等离子体的发射光谱,给出反应空间可能存在的反应基团有碳原子、碳离子、碳分子等,用拉曼光谱研究了薄膜的结构,证明所形成的薄膜为类金刚石膜,并得出碳原子和碳离子与薄膜的类金刚石结构有关。制备过程中,氢的参与有利于薄膜中金刚石成分的形成。空间分辨的原位激光等离子体发射光谱表明,在反应空间存在薄膜形成的最佳位置。     

热丝CVD沉积金刚石薄膜时的等离子体空间分布研究

采用热丝化学气相沉积(chemical vapor deposition,CVD)的方法,以丙酮为碳源生长金刚石薄膜时,利用等离子体发射光谱对生长过程中的等离子体空间分布进行了在线诊断。采用SEM,Raman光谱分别对沉积金刚石膜表面、断面的形貌和质量进行表征。光谱分析表明,对于线性阵列布丝情况下,中心区域与边缘区域的基团分布存在差异,中心区温度高,裂解能力强,基团强度高于两边,但中心区域基团特征峰强度的变化比等离子球平缓的多;距离热丝越远,热辐射减小,从丙酮分子中裂解出CH和CO等基团以及由原子H激发的H_β与H_α等强度降低,反而使得复合生成的C₂基团增加。SEM测试结果表明,当丝基间距为4.5,5.5,6.5 mm时,所沉积的金刚石薄膜表面由致密规则晶面向混乱转变,且单位时间内的生长速率也依次降低,此外,Raman光谱表明随着纵向间距的加大,金刚石薄膜的质量随之降低。这与诊断结果中CH和CO强度的降低,C₂基团强度增加及基团C₂/H_α比强度下降相吻合。     

Field emission properties of DLC and phosphorus-doped DLC films prepared by electrochemical deposition process

Field emission behavior of diamond-like carbon (DLC) and phosphorus-doped DLC (p-DLC) films prepared by electrochemical deposition process was comparatively investigated. It was shown phosphorus incorporation in the DLC film could lower the turn on field from 12 to 9.5 V/μm and increase the current density from 12.6 to 45.7 μA/mm² under high electric field. And better field emission performance of p-DLC films would be mainly attributed to the influence of the surface morphology and the changes of microstructure due to the phosphorus incorporation.     

等离子体增强化学气相沉积法制备含氢类金刚石膜的紫外Raman光谱和X射线光电子能谱研究

利用脉冲辉光放电的方法,在硅片上采用不同的沉积工艺制备了含氢类金刚石膜层,并采用Raman光谱和X射线光电子能谱(XPS)对膜层进行表征.用Raman光谱仪在波长为325 nm的紫外光源的激励下观察膜层的键结构.紫外Raman光谱对含氢类金刚石膜是非常有用的,它能有效避免可见光Raman光谱测量时的荧光干扰,清晰地得到膜层的D峰和G峰.同时利用XPS分析得到膜层的sp3键含量,并与Raman光谱所得数据进行比较.通过Raman光谱和XPS分析可以发现,在紫外光源的激励下,膜层的G峰峰位向高频移方向移动,G峰峰位、I(D)/I(G),G峰半高宽和sp3键含量之间存在一定的关系.     

高压PECVD技术沉积硅基薄膜过程中硅烷状态的研究

采用高压射频等离子体增强化学气相沉积(RF-PECVD)方法在不同功率下制备了一系列硅薄膜材料，研究了材料晶化率和生长速度随功率变化的规律， 进而研究PECVD方法沉积硅薄膜过程中的硅烷反应状态，并提出可以根据硅烷耗尽程度的不同将硅烷反应状态分为未耗尽、耗尽和过耗尽三种.然后，对不同硅烷反应状态下的材料结构、光电性能以及相应的电池进行了研究，并指出适合于太阳电池本征层的高质量微晶硅材料应该沉积在硅烷耗尽状态. 关键词： 耗尽状态 微晶硅 光发射谱     

Development of high sensitivity ethanol gas sensor based on Co-doped SnO2 nanoparticles by microwave irradiation technique

We have successfully synthesized Co doped SnO₂ nanoparticles by a simple microwave irradiation technique. Powder X-ray diffraction results reveal that the SnO₂ doped with cobalt concentration from 0 to 5 wt % crystallizes in tetragonal rutile-type structure. The products were annealed at 600 °C for 5 h in ambient atmosphere in order to improve crystallinity and structural perfection. Transmission electron microscopy (TEM) studies illustrate that both the undoped and Co doped SnO₂ crystallites form in spherical shapes with an average diameter of 30–15 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer's formula. A considerable red shift in the absorbing band edge was observed with increasing of Co content (0–5 wt %) by using UV–Vis diffuse reflectance spectroscopy (DRS). Oxygen-vacancies, tin interstitial and structural defects were analyzed using photoluminescence (PL) spectroscopy. Electron paramagnetic resonance (EPR) spectroscopic studies clearly showed that the Co²⁺ was incorporated into the SnO₂ host lattice. Ethanol gas sensitivity of pure and Co-doped (5 wt %) SnO₂ nanoparticles were experimented at ambient temperature using optical fiber based on clad-modified method. By modifying the clad exposure to ethanol vapor, the sensitivities were estimated to be 18 and 30 counts/100 ppm for undoped and Co-doped SnO₂ nanoparticles, respectively. These results show that the Co doping into SnO₂ enhances its ethanol gas sensitivity significantly.     

Metallic glass coating on metals plate by adjusted explosive welding technique

Using an adjusted explosive welding technique, an aluminum plate has been coated by a Fe-based metallic glass foil in this work. Scanning electronic micrographs reveal a defect-free metallurgical bonding between the Fe-based metallic glass foil and the aluminum plate. Experimental evidence indicates that the Fe-based metallic glass foil almost retains its amorphous state and mechanical properties after the explosive welding process. Additionally, the detailed explosive welding process has been simulated by a self-developed hydro-code and the bonding mechanism has been investigated by numerical analysis. The successful welding between the Fe-based metallic glass foil and the aluminum plate provides a new way to obtain amorphous coating on general metal substrates.     

类金刚石薄膜光学常数拟合模型的合理性研究

由于椭偏光谱测量结果不能直接反映所测量样品材料的结构和光学性质，所以需要利用最小二乘法来拟合分析椭偏光谱数据得到光学常数。而椭偏光谱分析依赖于构建的模型，且可能存在多模型解，因此考虑模型的合理性就显得十分必要。本文采用椭偏法测量了类金刚石薄膜(DLC)的光学常数，分析并拟合了脉冲真空电弧离子技术镀制的类金刚石薄膜的椭偏光谱．获得了光学常数，并对拟合模型的合理性和测量结果的可靠性进行了分析。     

Corona discharge as a temperature probe of atmospheric air microwave plasma jet

We developed and tested a new method for temperature measurements of near-LTE air plasmas at atmospheric pressure. This method is specifically suitable for plasmas at relatively low gas temperature (800–1700 K) with no appropriate radiation for direct spectroscopic temperature measurements. Corona discharge producing cold non-equilibrium plasma is employed as a source of excitation and is placed into the microwave plasma jet. The gas temperature of the microwave plasma jet is determined as the rotational temperature of N₂? produced in the corona discharge. The corona probe temperature measurement was tested by the use of a thermocouple. We found a fairly good agreement between the two methods after correcting the thermocouple measured temperatures for radiative losses. The corona probe method can be generally applied to determine the temperature of the near-LTE plasmas and contrary to the thermocouple it can be used for higher plasma temperatures and is not affected by radiative losses and problems of interaction with the microwave plasma and electromagnetic fields.     

Characterization and corrosion behavior of hydroxyapatite/zirconia composite coating on NiTi fabricated by electrochemical deposition

NiTi alloy is used as biomaterial due to its unique properties, but the high content of Ni (about 50 at.%) in biomedical NiTi is concerned. Hydroxyapatite and hydroxyapatite/zirconia composite coatings were directly electrodeposited on NiTi alloy surface. The coated samples were characterized using X-ray diffraction, scanning electron microscopy, infrared spectroscopy, bonding strength test, polarization and EIS. Results showed that when ZrO₂ was added into the electrolyte, morphology of HAP was changed from thin flake-flower-like crystals to needle-flower-like crystals, and coating was denser. Besides, HAP crystal grains in the coating were preferentially arranged in the [0 0 1] direction. Addition of ZrO₂ could improve the bonding strength between the coating and the substrate. Corrosion resistance of NiTi in the simulated body fluid at 37 °C was significantly improved by almost 60 times by electrodeposition of the hydroxyapatite/zirconia composite coating.     

Synthesis of CuS thin films by microwave assisted chemical bath deposition

In this study, oriented CuS nanoplates standing perpendicularly on F: SnO₂ (FTO) coated glass substrates have been prepared through a mild microwave assisted chemical bath deposition process in which copper acetate reacted with ethylenediamine tetraacetate acid disodium and thioacetamide in aqueous solution within 40 min. The effects of reaction time and microwave radiation on the treatment process were investigated. The morphology, structure, and composition of the yielded nanostructures have been confirmed by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), and scanning electron microscope (SEM). Also, the correlation between the reflectance, transmittance coefficient in the UV and the thickness of films was established. Furthermore, a two-point probe was used for resistivity measurements. We believe this simple chemical conversion technique can be further extended to the synthesis of other semiconductors with various morphologies.     

New measurements of the microwave spectrum of formamide

New measurements of the microwave spectrum of formamide have been obtained in the frequency range from 49 to 340 GHz using the microwave spectrometer at the Institute of Radio Astronomy of NASU, Kharkov, Ukraine. An analysis of the rotational spectra of the ground, v₁₂, v₉, v₁₁ and 2v₁₂ excited vibrational states of the main isotopic species as well as of the ground states of the ¹³C, ¹⁵N and ¹⁸O substituted species has been carried out using SPFIT/SPCAT programs. The analysis of a strong Coriolis interaction coupling between v₉, v₁₁ and 2v₁₂ vibrational states of formamide has been also fulfilled as well as the analysis of the quadrupole hyperfine structure of the observed transitions. For the first time the quadrupole coupling parameters for the excited vibrational states and for the ¹⁸O substituted species of formamide were determined.