共查询到19条相似文献,搜索用时 171 毫秒
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在射频输入功率为400W,气压为0.8Pa的条件下,使用光强标定的发射光谱方法研究了感应耦合H2/C4F8等离子体中CF, CF2, H和F基团的相对密度随流量比R=H2/(H2+C4F8)的变化情况,而HF基团相对密度的变化由四级质谱仪探测得到。结果表明等离子体活性先随着R的增加而升高,然后随着R的进一步增加而下降。在流量比从0逐渐上升到0.625的过程中,CF和CF2基团的相对密度不断降低。实验中测得的CF基团的相对密度[CF]与理论计算得到的[CF]有很好的一致性说明了电子与CF2基团的碰撞反应是CF基团产生的主要原因。文中还讨论了HF基团。 相似文献
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基于空气放电非平衡等离子体动力学,对空气放电进行了数值计算,分析了放电后等离子体中的主要粒子(N2(v6),N2(A3),O2(a1),O和O3)数密度随起始温度、电子数密度和约化场强的变化趋势。计算结果表明,随着初始温度的升高,空气放电产生的粒子数密度增加。温度为300 K时,放电产生的O原子数密度最大值约为4.90×7 cm-3,而当温度升高到400 K和500 K时,O原子数密度的最大值则相应地增加到5.2×1010 cm-3和5.51×1010 cm-3。约化场强的影响与温度类似,其中氮气的振动激发态N2(v6)数密度随约化场强的变化幅度不明显。电子数密度增加,粒子数密度大幅增加,氮分子的激发态N2(A3)粒子数密度与电子数密度保持严格的线性关系。 相似文献
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采用高H2稀释的SiH4等离子体放电, 特别是甚高频等离子体增强化学气相沉积技术是当前高速制备优质微晶硅薄膜的主流方法. 尽管在实验上取得了很大的突破, 但其沉积机理一直是研究的热点和难点. 本文通过建立二维时变的轴对称模型,在75 MHz放电频率下, 对与微晶硅沉积非常相关的甚高频电容耦合氢等离子体放电进行了数值模拟, 研究了沉积参数对等离子体特性的影响, 并与光发射谱(OES)在线监测结果进行了比较. 结果表明: 电子浓度 ne在等离子体体层中间区域最大, 而电子温度 Te及Hα与Hβ的数密度在体层和鞘层界面附近取极大值; 当气压从1 Torr (1 Torr=133.322 Pa)增大至5 Torr时, 等离子体电势单调降低, 在体层中间区域 ne先快速增大然后逐渐减小, Te先下降后趋于稳定; 随着放电功率从30 W增大到70 W, 电子浓度 ne及Hα与Hβ的数密度均线性增大, 而电子温度 Te基本保持不变; OES在线分析结果与模拟结果符合得很好. 相似文献
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用电子密度泛函理论研究了N-质子化corrole(H4Cor+)和meso位芳基取代质子化corroles(H4TPC+、H4TpFPC+和H4TdCPC+)的几何构型、内消旋反应机理以及电子光谱. 结果表明,这些化合物均有两种稳定构型(势能面极小),一个为C2对称性的S1(最稳定构型),另一为C1对称性的S2,其中S1的能量比S2低约15.8~18.5 kJ/mol.S1和S2的corrole环都呈现明显的面外扭曲变形. 手性S1的两个对映异构体之间的转化是一个以S2为中间态的多步过程. 用TDDFT计算了它们的紫外可见电子吸收光谱和圆二色谱(ECD). 与H4Cor+相比,H4TPC+、H4TpFPC+和H4TdCPC+的紫外可见吸收都发生了明显红移,且它们的Q带都因芳基取代基与corrole环之间的π-π共轭而明显增强. 计算表明,质子化corrole的若干相邻电子跃迁的旋转强度符号相反,表明ECD谱可能是研究其电子跃迁的有用工具. 相似文献
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For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing a mass spectrometer equipped with a movable gas sampling apparatus. The experimental results demonstrate that the relative densities of SiCln (n=0-2) radicals have peak values at the position of 10 mm above the powered electrode along the axial direction; the relative densities of the Si and SiCIn (n=1, 2) radicals have peak values at the positions of 27mm and 7 mm away from the axis along the radial direction, respectively. Generally speaking, in the whole SICl4 plasma bulk region, the relative density of Si is one order of magnitude higher than that of SICl, and the relative density of SiCl is several times higher than that of SICl2. This reveals that Si and SiCl may be the primary growth precursors in forming thin films. 相似文献
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The N2-H2 plasma gas mixture, generated in a 50?Hz pulsed dc discharge system with active screen cage, is characterized by optical emission spectroscopy (OES), as a function of gas pressure, the fractions of hydrogen and current density. The N2 dissociation degree and N atomic density was measured with actinometery where argon gas is used as actinometer. It was shown that the increase in hydrogen fraction enhances the dissociation of N2, until the maximum of 40%. The excitation temperature is determined from Ar-I emission line intensities by using the simple Boltzmann plot method. The dissociation fraction and excitation temperature is found to increase with hydrogen mixing in nitrogen plasma. 相似文献
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In-situ germanium content monitoring and its characteristics in SiH4/GeH4/H2 plasmas was studied during hydrogenated amorphous silicon–germanium (a-SiGe:H) film depositions. Since an appropriate band-gap profiling in a-SiGe:H deposition is very important to achieve high efficiency solar cell, the accurate monitoring and control of Ge contents are required. In this work, we found the spectral intensity ratio of silicon atom (288.2 nm) and germanium atom (303.9 nm) emission has strong relation with Ge content in plasmas. In typical, band-gap energy of films was decreased with the increasing of gas flow ratio GeH4/SiH4. However, at different total flow rate of GeH4, the band-gap was different for same gas flow ratio cases because the Ge content in plasmas was changed due to the changes of electron temperature by hydrogen dilution. On the other hand, the emission intensity ratio Ge/Si detected the band-gap variation. Using this method, therefore, we measured and control Ge/Si to make a U-shape band-gap profile which was proved by an ellipsometer and Auger electron spectroscopy depth profile analysis. 相似文献
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Diagnosis of a low pressure capacitively coupled argon plasma by using a simple collisional-radiative model 下载免费PDF全文
This paper proposes a simple collisional-radiative model to characterise capacitively coupled argon plasmas driven by conventional radio frequency in combination with optical emission spectroscopy and Langmuir probe measurements. Two major processes are considered in this model, electron-impact excitation and the spontaneous radiative decay. The diffusion loss term, which is found to be important for the two metastable states (4s[3/2]2, 4s'[1/2]0), is also taken into account. Behaviours of representative metastable and radiative states are discussed. Two emission lines (located at 696.5 nm and 750.4 nm) are selected and intensities are measured to obtain populated densities of the corresponding radiative states in the argon plasma. The calculated results agree well with that measured by Langmuir probe, indicating that the current model combined with optical emission spectroscopy is a candidate tool for electron density and temperature measurement in radio frequency capacitively coupled discharges. 相似文献
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P Meenakshi Raja Rao P Saraswathy G Krishnamurty R K Rout S K H Auluck Anurag Shyam I V Kulkarni Dipak H Oza 《Pramana》1989,32(5):627-639
Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH β andH λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C4 for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines. 相似文献
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《Current Applied Physics》2010,10(6):1456-1460
This work aims at investigation of the validity of the electron excitation temperature (Texc) by optical emission spectroscopy (OES) as an alternative diagnostic to the electron temperature (Te). The excitation and the electron temperatures were measured at a wide range of gas pressures and input powers in different plasmas such as capacitively-coupled, inductively-coupled, and magnetron direct current plasmas. As a result, both temperatures were found to decrease with an increase in pressure, whereas they not very dependent on power, indicating that Texc showed a tendency identical to that of Te as pressure and power were varied. This result suggests that Texc measurement can be an alternative diagnostic for Te measurement once the ratio of the two temperatures is found in advance through a calibration experiment especially for low pressure high electron density industrial processing plasmas in which probe measurements are limited. 相似文献
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JinHua Cui ZhenFeng Xu JiaLiang Zhang QiuYue Nie GenHui Xu LongLiang Ren 《中国科学G辑(英文版)》2008,51(12):1892-1896
Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy.
In this study, CH4+H2 discharge plasma was on-line diagnosed by optical emission spectra so as to characterize the discharge system and to do spade
work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas.
The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure. The diagnostic method is easy, efficient and fairly precise. A serious error in
a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures
in plasmas.
Supported by the National Natural Science Foundation of China (Grant Nos. 29776037 and 10675028) and the Science and Technology
Development Foundation of SINOPEC (Grant No. X500005) 相似文献
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M.H. Jeon A.K. Mishra S.-K. Kang K.N. Kim I.J. Kim S.B. Lee T.H. Sin G.Y. Yeom 《Current Applied Physics》2013,13(8):1830-1836
60 MHz pulsed radio frequency (rf) source power and 2 MHz continuous wave rf bias power, were used for SiO2 etching masked with an amorphous carbon layer (ACL) in an Ar/C4F8/O2 gas mixture, and the effects of the frequency and duty ratio of the 60 MHz pulse rf power on the SiO2 etch characteristics were investigated. With decreasing duty ratio of the 60 MHz pulse rf power, not only the etch rate of SiO2 but also the etch rate of ACL was decreased, however, the etch selectivity of SiO2 over ACL was improved with decreasing the duty ratio. On the other hand, when the pulse frequency was varied at a constant duty ratio, no significant change in the etch rate and etch selectivity of both materials could be observed. The variation of the etch characteristics was believed to be related to the change in the gas dissociation characteristics caused by the change in the average electron temperature for different pulsing conditions. The improvement in the etch selectivity with the decrease of duty ratio, therefore, was related to the decreased gas dissociation of C4F8 by the decrease of average electron temperature and, which resulted in a change in composition of the fluorocarbon polymer on the etched materials surface from C–C rich to CF2 rich. With decreasing the duty ratio, not only the etch selectivity but also the improvement in the SiO2 etch profile could be observed. 相似文献
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Humaira Latif Sadaf Jamil Rana Babar Shahzad Khan Sardar Sikandar Hayat 《辐射效应与固体损伤》2017,172(11-12):851-865
Trace rare gas optical emission spectroscopy (TRG-OES) is carried out to determine the excitation temperature, vibrational temperature, dissociation fraction and nitrogen (N) atom density in 50?Hz active screen cage nitrogen plasma, as a function of discharge parameters (current density and fill pressure) and hydrogen concentrations. The excitation temperature is determined from Ar–I emission lines and is found to increase with hydrogen mixing. In a similar fashion, the vibrational temperature of second positive system is determined and found to have increasing trend with hydrogen addition. The dissociation fraction increases with hydrogen concentration up to 40% H2 in the nitrogen plasma, so as the nitrogen atom density. 相似文献