The effect of initial discharge conditions on the properties of microcrystalline silicon thin films and solar cells

This paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon ($\mu $c-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry, through delaying the injection of SiH7280N, 7830G, 8115Hhttp://cpb.iphy.ac.cn/CN/10.1088/1674-1056/19/5/057205https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=111771back diffusion, microcrystalline silicon, thin film, Raman crystallinityProject supported by the State Key Development Program for Basic Research of China (Grant No.~2006CB202601).This paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon ($\mu $c-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry, through delaying the injection of SiH$_{4}$ gas to the reactor before plasma ignition. By comparing with standard discharge condition, delayed SiH$_{4}$ gas condition could prevent the back diffusion of SiH$_{4}$ from the reactor to the deposition region effectively, which induced the formation of a thick amorphous incubation layer in the interface between bulk film and glass substrate. Applying this method, it obtains the improvement of spectral response in the middle and long wavelength region by combining this method with solar cell fabrication. Finally, results are explained by modifying zero-order analytical model, and a good agreement is found between model and experiments concerning the optimum delayed injection time.back;diffusion;microcrystalline;silicon;thin;film;Raman;crystallinityThis paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon(μc-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry,through delaying the injection of SiH4 gas to the reactor before plasma ignition.Compared with standard discharge condition,delayed SiH4 gas condition could prevent the back diffusion of SiH4 from the reactor to the deposition region effectively,which induced the formation of a thick amorphous incubation layer in the interface between bulk film and glass substrate.Applying this method,it obtains the improvement of spectral response in the middle and long wavelength region by combining this method with solar cell fabrication.Finally,results are explained by modifying zero-order analytical model,and a good agreement is found between the model and experiments concerning the optimum delayed injection time.     

用微波ECR等离子体溅射法在蓝宝石(0112)晶面上生长ZnO薄膜的研究

蓝宝石上外延生长ZnO薄膜在表面波和声光器件中有重要的应用．用微波电子回旋共振(ECR)等离子体溅射法在蓝宝石(0112)晶面上外延生长了ZnO薄膜,膜无色透明,并且表面光滑,基片温度为380℃,为探索沉积工艺参数对薄膜结构的影响,用XRD对不同基片温度和沉积速率生长的ZnO薄膜进行了研究．     

金刚石薄膜负偏压形核的边缘效应

 在微波等离子体化学气相沉积装置中，研究了金刚石薄膜在Si (100)面上的负偏压形核行为，结果表明，偏压大小对金刚石的形核均匀性有显著影响，而甲烷浓度主要影响形核时间，对金刚石的最大核密度影响不大。在硅片尺寸小于钼支撑架时，形核行为存在明显的边缘效应，即在偏压值低于-150 V时，硅片边缘金刚石核密度急剧降低，远低于硅片中央；在甲烷浓度比较低时，硅片边缘核密度要高于中间。研究表明，造成这种现象的主要原因是硅片下的钼支撑架发射电子所致，过量的原子H对金刚石的形核是不利的。     

氢气浓度对掺氮超纳米金刚石薄膜的影响

采用微波等离子体化学气相沉积法,以甲烷和氮气为气源,通过改变反应气体中氢气的浓度,在硅衬底上沉积出掺杂氮的超纳米金刚石膜.并利用扫描电子显微镜,拉曼光谱仪,X射线衍射仪,霍尔效应测试仪分别对掺杂氮的超纳米金刚石膜的表面形貌,组成结构及导电性能进行了进行表征,重点研究了氢气浓度对薄膜特性的影响.结果表明:随着氢气浓度的增加,薄膜的晶粒尺寸逐渐增大;薄膜的质量提高,且由G峰漂移引起的压应力逐渐减小;薄膜导电性变差.     

MPCVD等离子体的发射光谱研究

在2.45 GHz, 800 W微波等离子体化学气相沉积装置上,利用发射光谱对CH₄/H₂等离子体进行在线诊断,分析了等离子体中存在的基团,研究了甲烷浓度对各基团浓度及基团的空间分布的影响。结果表明：等离子体中存在CH, H_α, H_β, H_γ, C₂ 基团和Mo杂质原子,随着甲烷浓度的升高,各基团的发射光谱强度均有增加,其中C₂基团强度显著增加。CH与H_α基团的发射光谱强度比值随甲烷浓度的增加变化不大,而C₂与H_α基团的发射光谱强度的比值随甲烷浓度的增加而显著增大。另外,甲烷浓度的增加使得等离子体中各基团在空间分布的均匀性变差。     

硫/碳纤维复合膜的制备及电化学性能

采用热丝化学气相沉积法先在铁箔上沉积了致密的碳纤维膜,后通过加热渗硫法制得硫/碳纤维复合膜,并将其用作锂硫电池正极材料。通过扫描电子显微镜和X射线衍射表征膜的形貌和结构,采用恒流充放电法和阻抗测量法测试复合膜的电化学性能。结果表明,随热丝与铁箔基底间距减小,碳纤维膜致密度先升高后降低;随H2与(Ar+C3H6O)的体积流量比减小,碳纤维膜致密度升高。当丝基距为6 mm,流量比为30/40时,铁箔上沉积了厚度为50μm的致密碳纤维膜,其中碳纤维有良好的垂直取向性和较高结晶度。在硫/碳纤维复合膜正极中,密集的碳纤维形成均匀分布且垂直取向性良好的导电骨架,当电流密度为0.4 mA.cm-2时,硫/碳纤维复合膜正极的初次放电比容量为1 128 mAh.g-1,50次循环后的放电比容量为811 mAh.g-1。     

大气微波等离子体炬装置设计及实验研究

大气微波等离子体矩具有无电极放电污染、无需昂贵真空设备和易于连续化加工等特点,具有广阔的应前景.本文设计了一套基于BJ26波导的微波能利用率高、稳定性好的大气微波等离子体装置.该装置由最高输出功为800W的2.45GHz程控微波源、调配系统、波导谐振腔和耦合天线组成.利用加装游标卡尺的接触式短路活塞,微波反射面位置进行...     

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在非对称磁镜场微波ECR等离子体中引入了磁电加热系统,研究了电极环大小、轴向位置以及双环加热对离子温度的影响.结果表明,大小合适的电极环能有效提高离子的加热温度,且最优电极环尺寸主要取决于离子回旋半径.电极环轴向位置的选择主要与磁镜场位形有关,将电极环置于磁镜场中部的弱磁场位置时最有利于离子温度的提高.采用双电极环加热能进一步提高离子温度,并且其加热效果是单环加热的两倍.