微波功率对a-C:F薄膜结构和光学性质的影响

用苯 (C6H6)和四氟甲烷 (CF4 )混合气体作源气体 ,用微波电子回旋共振等离子体化学气相沉积技术制备了含氟非晶碳膜 (a C :F)。着重讨论了输入的微波功率对成膜结构和性质的影响。我们对沉积的膜作了膜厚、扫描电子显微表面形貌 (SEM)、紫外 -可见光透射谱 (UV -VIS)、傅立叶红外变换 (FTIR)等的测量。结果表明随着微波功率的增加沉积速率一直在上升 ;同时膜中缺陷增多 ;从FTIR的结果我们发现膜中主要以C -F、CF2 和F -芳基成键 ;通过UV -VIS吸收谱的测量的结果我们求出了折射率和光学带隙 ;并且将光学带隙和膜中的sp2 碳浓度建立关系     

ECR-CVD方法生长a-SiNx:H薄膜的研究

使用微波电子回旋共振等离子体化学气相沉积(ECR-CVD)方法室温生长了非晶氢化的氮化硅薄膜,通过改变前驱气体(SiH4 80%Ar和NH3)的流量比,研究了薄膜的生长速率、等离子体的发射光谱和薄膜的红外特性.结果表明:随着NH3流量的增加,氮化硅薄膜的生长速率呈下降趋势,这主要是由于等离子体中的气相前驱成分之一硅基团浓度的不断下降所导致的;随着NH3流量的增加,薄膜中键合了较多的具有较高电负性的N原子是Si-N和Si-H伸缩振动发生蓝移的主要原因.红外光谱的定量计算表明所制备的氮化硅薄膜具有相对较低的H浓度,约15%左右.文中对氮化硅薄膜的生长机制也进行了讨论.     

功率和温度对a-C:F:H膜表面形貌和结构的影响

分析薄膜的表面形貌对其生长机理和光学性质研究有着十分重要的作用。本文使用CF4和CH4为源气体，利用射频等离子体增强化学气相沉积（RF—PECVD）法在不同射频功率和沉积温度下制备了掺氟氢化无定形碳（a—C：F：H）薄膜，并在N2气氛中进行了不同温度的退火处理。用原子力显微镜（AFM）和扫描电子显微镜（SEM）观察了薄膜表面形貌，发现低功率下沉积的薄膜表面均匀性好、缺陷少；在低温下沉积的薄膜表面光滑，而高温下粗糙；真空低温退火可使薄膜表面形貌得到改善，但薄膜内空洞增加，退火温度过高，薄膜的结构发生变化，且在薄膜表面发生皲裂现象。用Raman光谱对薄膜内的结构变化进行了进一步的分析。     

氟化非晶态碳膜(a-C:F)的制备与表征

采用等离子体浸没与离子注入装置,以CF4和CH4作为源气体,在Si(100)基片上制备了含氟量不同的一系列氟化非晶态碳膜。通过XPS、FTIR和Raman对其结构进行了表征。采用躺滴法测量薄膜与双蒸水之间的接触角。薄膜硬度通过纳米压痕仪进行测量。XPS和FTIR结果表明存在C—CF、C—Fx基团和少量的氧。我们认为薄膜中存在的氧元素是由于薄膜在正常存放时发生了时效过程,其中的悬挂键发生化学吸附反应引起的。Raman和接触角测量结果表明,随着氟元素含量的逐渐增加,薄膜从典型的类金刚石状结构逐渐转化为类聚合物状结构,接触角逐渐增大。纳米压痕测量结果表明,氟元素的加入使得薄膜的硬度有很大程度的降低。     

真空退火对a-C:F:H薄膜的结构与光学带隙的影响

使用CF4和CH4为源气体,利用射频等离子体增强化学气相沉积(RF-PECVD)法制备了掺氟非晶碳(a-C:F:H)薄膜,并在N2气氛中进行了不同温度的退火.用原子力显微镜(AFM)观察了薄膜在退火前后表面形貌的变化,发现退火后薄膜表面变得平坦,疏松.用紫外-可见光透射光谱(UV-VIS)并结合傅里叶变换红外光谱(FTIR)和喇曼(Raman)光谱对薄膜进行了分析,获得了薄膜化学键结构和光学带隙的变化情况;发现薄膜的化学键结构和光学带隙与真空退火密切相关,高温退火后薄膜化学键结构:CHx(x=1,2,3下同)、F-芳基、CF2和CF等基团的含量改变;薄膜的光学带隙决定于CHx、退火后CHx含量减少导致薄膜光学带隙的减小.     

热丝辅助ECR-CVD制备a-Si:H薄膜的红外和光致衰退研究

采用热丝辅助MWECR-CVD系统制备出了a-SiH薄膜.应用傅立叶红外仪测量了薄膜的红外谱,用共面蒸铝电极法测量了薄膜的光电导.通过比较A样品(加入热丝)和B样品(未加热丝),得出在热丝辅助MWECR-CVD系统制备非晶硅薄膜过程中,热丝的光照对薄膜的抗衰退起到了关键作用,用该系统制备非晶硅薄膜,大大降低了薄膜中的总氢含量,提高了薄膜的稳定性,同时,Si-H键合体的摇摆模发生了红移.     

电子回旋共振—微波等离子体化学气相沉积法制备a-C:H(N)薄膜

采用电子回旋共振 -微波等离子体化学气相沉积技术 ,使用 CH4 和 N2 混合气作为反应气体 ,在硅衬底上制备掺氮含氢非晶碳 (a- C∶ H(N) )薄膜。紫外 Ram an光谱证实了薄膜的类金刚石特性 ;傅立叶变换红外光谱表明薄膜中存在 CH和 CN键结构。采用原子力显微镜 (AFM)观察薄膜的微观表面形貌 ,结果表明薄膜表面光滑。论文详细叙述了薄膜制备工艺 ,对测试结果进行了分析讨论 ,也对这种薄膜在微电子机械系统中的潜在应用进行了探讨     

乙烯掺杂APCVD法沉积非晶硅薄膜的光学特性

通过硅烷、乙烯和氮气的混合气体在620下采用常压化学气相沉积(APCVD)法沉积了非晶硅薄膜,讨论了乙烯/硅烷的体积比(R=VC2H4/VsiH4)对薄膜的光学性质的影响.用Raman光谱、红外光谱和紫外-可见光光谱仪对薄膜进行表征.结果表明通过乙烯掺杂制备的薄膜样品中存在着Si-C键,在R值变化的开始阶段薄膜的光学带隙随着R值增大而增大,在R=0.1时达到最大值,然后随着R值的增大而减小.     

具有低摩擦因数的a-C:H薄膜研究

a-C:H薄膜有内应力大、热稳定性差、大气环境下摩擦因数高（0.1～0.4）等一些固有缺陷。采用等离子体辅助化学气相沉积技术,以乙炔和六甲基二硅氧烷为反应前驱体制备了具有低摩擦因数的硅氧共掺a-C:H薄膜。利用扫描电镜、拉曼光谱、纳米压痕及划痕分别研究了薄膜的微观结构和力学性能。结果表明,硅氧共掺a-C:H薄膜具有典型的非晶碳结构,并且展现出较高的硬度和弹性模量以及良好的膜基结合力,大气下的摩擦因数介于0.04～0.08之间,气压为10 kPa和5 kPa时摩擦因数可低至0.02。薄膜的低摩擦性能主要来源于薄膜本身的特性（硅氧的掺杂）和服役环境中大气压力的共同作用。     

Composite Ag/C:H:N films prepared by planar magnetron deposition

Composite Ag/C:H:N films were deposited by means of an unbalanced magnetron operated in a gas mixture of nitrogen and n-hexane. Composition of the films was controlled by electric power delivered to the magnetron and by ratio of nitrogen and n-hexane in the working gas mixture. The films were characterized using transmission electron microscopy, by the absorption spectra in visible and near infrared regions and by Fourier transform infrared spectroscopy. Immediately after film deposition and without breaking vacuum (in situ) corresponding vibration infrared spectra were scanned and their evolution during ageing of the films was monitored. Wettability as determined from water contact angle was improved with raising nitrogen contents, i.e. with increasing the electric power and the ratio of nitrogen/n-hexane in the working gas mixture. The increased wettability is likely caused by presence of NH_x groups in Ag/C:H:N films. The incorporation of nitrogen effectively prevents the formation of carboxylate groups on the silver inclusions surfaces during the aging in the open air. In addition, the oxidation mechanism of the polymer matrix is modified.     

Band gap enhancement on metal chelation: Growth and characterization of cobalt chelated glycine single crystals for optoelectronic applications

Single crystals of Diaqua Bisglycine Cobaltous Chloride (DBGCoCl) have been synthesized and grown by slow evaporation method. Grown crystals were subjected to FTIR and XRD studies for structural confirmation. The DBGCoCl crystallizes in the monoclinic system with the space group P2₁/c. The UV–vis spectrum for the pure glycine as well the cobalt chelated glycine have been recorded. The lower cutoff wavelength observed from the UV–vis spectrum is found to decrease by the chelation of cobalt with glycine and this leads to an increase in the band gap of the compound from 3.13 eV to 4.91 eV. The optical constants were calculated and illustrated graphically. Mechanical hardness of the grown crystal DBGCoCl was studied and Vickers hardness number was calculated. The work hardening coefficient (n) was determined to be 1.365 and the stiffness constants for different loads were calculated and reported. The thermal stability of the grown crystal has been studied using TGA and DTA. The crystal is thermally stable up to 116.86 °C.     

沉积温度对a-C:F薄膜结构与热稳定性的影响

在不同的沉积温度下，利用CHF3和C2H2为气体源，在微波电子回旋共振等离子体化学气相沉积(ECR-CVD)系统中制备了氟化非晶碳(-C：F)薄膜，为了研究其热稳定性，薄膜在500℃的真空中作了退火处理。测量了退火前后其电学、光学性质的变化，使用FFIR、Raman、XPS方法考察了其结构随沉积温度的变化，分析了性质同结构之间的关联。结果表明，在高的沉积温度下制备的薄膜中的F／C比较低，CF2和CF3键成分较少而以CF键成分为主，其交联程度高，因而具有较好的热稳定性。     

氢化非晶硅薄膜的红外光谱分析和桥键氢扩散假设

通过红外透射光谱研究了在光诱寻退火中退火条件对氢化非晶硅薄膜的结构和光电特性的影响,实验所用样品采用热丝辅助微波电子回旋共振化学气相沉积方法制备。我们用桥键氢扩散模型来解释退火中的不同现象。样品的红外光谱在630和2000cm^-1处的吸收系数有所增加,说明了原先的成键氢发生了移动和溢出,我们认为通过光诱导产生栽流子的非辐射复合以及桥键氢和深俘获氢原子的交换,产生了大量的桥键氢原子,它们相互结合形成分子氢,氢溢出要优于氢团聚。     

a—C：H（N）薄膜的生物相容性

采用射频－直流等离子增强化学气相沉积法用Ｃ２Ｈ２与Ｎ２的混合气体制备了ａ－Ｃ：Ｈ（Ｎ）薄膜,用动物急性实验法和细胞毒性实验法研究了ａ－Ｃ：Ｈ（Ｎ）薄膜的生物相容性。结果表明,ａ－Ｃ：Ｈ（Ｎ）薄膜的生物相容性优于常用生物材料纯Ｔｉ,且能为细胞的生长提供合适的生长表面。     

Characterization of Si:O:C:H films fabricated using electron emission enhanced chemical vapour deposition

Silicon-based polymers and oxides may be formed when vapours of oxygen-containing organosilicone compounds are exposed to energetic electrons drawn from a hot filament by a bias potential applied to a second electrode in a controlled atmosphere in a vacuum chamber. As little deposition occurs in the absence of the bias potential, electron impact fragmentation is the key mechanism in film fabrication using electron-emission enhanced chemical vapour deposition (EEECVD). The feasibility of depositing amorphous hydrogenated carbon films also containing silicon from plasmas of tetramethylsilane or hexamethyldisiloxane has already been shown. In this work, we report the deposition of diverse films from plasmas of tetraethoxysilane (TEOS)-argon mixtures and the characterization of the materials obtained. The effects of changes in the substrate holder bias (V_S) and of the proportion of TEOS in the mixture (X_T) on the chemical structure of the films are examined by infrared-reflection absorption spectroscopy (IRRAS) at near-normal and oblique incidence using unpolarised and p-polarised, light, respectively. The latter is particularly useful in detecting vibrational modes not observed when using conventional near-normal incidence. Elemental analyses of the film were carried out by X-ray photoelectron spectroscopy (XPS), which was also useful in complementary structural investigations. In addition, the dependencies of the deposition rate on V_S and X_T are presented.     

Studies of interaction of amines with TOPO/TOP capped CdSe quantum dots: Role of crystallite size and oxidation potential

This work reports the interaction of aliphatic (triethyl amine, butyl amine) and aromatic amines (PPD, aniline) with CdSe quantum dots of varied sizes. The emission properties and lifetime values of CdSe quantum dots were found to be dependent on the oxidation potential of amines and crystallite sizes. Smaller CdSe quantum dots (size 5 nm) ensure better surface coverage of amines and hence higher quenching efficiency of amines could be realized as compared to larger CdSe quantum dots (size 14 nm). Heterogeneous quenching of amines due to the presence of accessible and inaccessible set of CdSe fluorophores is indicated. PPD owing to its lowest oxidation potential (0.26 V) has been found to have higher quenching efficiency as compared to other amines TEA and aniline having oxidation potentials 0.66 and >1.0 V, respectively. Butyl amine on the other hand, plays a dual role: its post-addition acts as a quencher for smaller and enhances emission for larger CdSe quantum dots, respectively. The beneficial effect of butyl amine in enhancing emission intensity could be attributed to enhance capping effect and better passivation of surface-traps.