纳米Si薄膜的压阻效应

纳米Ｓｉ薄膜由大量的超微Ｓｉ晶粒和大量的晶粒间界面区组成。这一特殊的结构造成纳米Ｓｉ薄膜具有较大的压阻效应。本文讨论了薄膜微结构对其压阻效应的作用。认为纳米Ｓｉ薄膜材料是一种优秀的传感器材料。     

反应蒸发制备nmSi—SiOx发光薄膜

报道了用真空反应蒸发制备ｎｍＳｉ／ＳｉＯｘ薄膜,制备出含有不同纳米尺寸硅颗粒的薄膜,研究了不同条件下得到的ｎｍＳｉ－ＳｉＯｘ薄膜的结构和组分,实验发现以ＳｉＯ为蒸发源制备的薄膜能够实现光致发光。初步分析ｎｍＳｉ－ＳｉＯｘ薄膜发光机制可能是由纳米硅最子效应引起的,界面效应和缺陷对薄膜ＰＬ可能没有贡献,解释了有纳米硅颗粒的存但观察了ＰＬ的原因。     

高氢稀释硅烷加乙烯法制备纳米硅碳薄膜

在等离子体化学气相沉积系统（ＰＥＣＶＤ）中，使用高氢稀释硅烷（ＳｉＨ４）加乙烯（Ｃ２Ｈ４）为反应气氛制备了纳米硅碳（ｎｃ－ＳｉＣｘ＾２Ｈ）薄膜，随着（Ｃ２Ｈ４＋ＳｉＨ４）／Ｈ２（Ｘｇ）从５％时，由于Ｈ蚀刻效应的减弱，薄膜的晶态率从４８％下降到８％，平均晶粒尺寸在３．５－１０ｎｍ。当Ｘｇ≥６％时，生成薄膜为非晶硅碳（ａ－ＳｉＣｘ＾２Ｈ）薄膜。ｎｃ－ＳｉＣｘ＾２Ｈ薄膜的电学性质具有与薄膜的晶态率紧密相     

纳米硅基薄膜光致发光机制的初步研究

用等离子体化学气相沉积方法制备氢化非晶硅合金薄膜，经高温退火及高温氧化可制备纳米尺寸的晶粒，室温下能发出可见光。实验表明，高温氧化后的纳米颗粒被镶嵌在ＳｉＯ２的无序网络中，其晶粒尺寸减少，而发光强度增强，发光峰位置向短波方向移动。这些结果说明，发光来源于纳米晶粒的量子尺寸效应和覆盖晶粒表面的ＳｉＯ２层的发光中心。     

溅射PZT薄膜的晶体结构和快速热处理

采用常温射频（ＲＦ）溅射法和快速热处理相结合的技术，在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上，制备出具有铁电性的ＰＺＴ薄膜。研究了快速热处理工艺条件对ＰＺＴ薄膜性能的影响。通过Ｚ射线衍射法、ＳＥＭ和ＡＥＳ等方法，分析了ＰＺＴ薄膜的晶体结构、微结构、薄膜和电极间的界面效应。     

反应蒸发沉积的纳米硅—氧化硅薄膜的发光及其氧的存在形态

通过改变蒸发源，衬底温度和氧的流量，用反应蒸发法制备了不同晶粒尺寸的Ｓｉ／ＳｉＯｘ薄膜，用Ｘ射线衍射，Ｘ光电子能谱和红外光谱分别测试了薄膜的结构，组分及氧在薄膜中的存在形态。     

特种化学气相沉积法制备大面积纳米硅薄膜的微结构和电学性能研究

采用可与Si平面工艺兼容的特殊设计的化学气相沉积系统在玻璃衬底上制备了大面积的纳米Si薄膜.高分辨率电子显微镜和选区电子衍射分析表明,成膜温度对薄膜微结构有关键影响,衬底温度的升高促进了薄膜晶态率的提高和Si晶粒的长大.660℃成膜时非晶Si薄膜基体中镶嵌了尺寸为8～12nm,晶态率为50%的纳米Si晶粒,具有明显的纳米Si薄膜微结构特征.用变温薄膜暗电导率测试系统研究表明,随成膜温度的升高,薄膜的晶态率提高、室温暗电导率提高而相应的电导激活能降低,用热激活隧道击穿机制解释了纳米Si薄膜微结构与特殊电学性能的关系.研究了原位后续热处理对薄膜微结构和电学性能的影响,发现延长热处理时间以及采用低温成膜、高温后续退火的热处理方法能有效提高纳米Si薄膜的晶态率,进而提高其室温暗电导率.     

金刚石薄膜压力传感器的研究

金刚石的许多性质使它成为微结构为器件的优异材料。现已证明金刚石薄膜有压阻效应,这个性能打开了金刚石薄膜在压力传感器领域的应用,研究了金刚石薄膜的欧姆接触,热敏特性和压阻特性,研究表明金刚石薄膜可制成适于高温工作的传感器。     

氧化物La-Ca-Mn-O巨磁电阻薄膜的制备及其结构特性的研究

采用磁控溅射方法在ＺｒＯ２（００１）、Ｓｉ（００１）和玻璃衬底上成功地制备了ＬａＣａＭｎＯ（以下简称为ＬＣＭＯ）巨磁电阻薄膜。Ｘ－射线分析表明，ＺｒＯ２的晶格常数与ＬＣＭＯ的晶格常数失配虽然较大，仍可得到较好的ＬＣＭＯ薄膜。在Ｓｉ片上难以制备出致密完整的ＬＣＭＯ薄膜，其原因有待查明。玻璃衬底上可以获得纯相的ＬＣＭＯ巨磁电阻薄膜，在ＺｒＯ２衬底上制备的ＬＣＭＯ薄膜，其巨磁电阻效应在１５０Ｋ，３０００Ｇａｕｓ下达１３％左右。     

氢化非晶硅激光诱导结晶膜微结构的椭偏谱分析

用ＸｅＣｌ准分子激光器对氢化非晶硅（ａ－Ｓｉ：Ｈ）薄膜进行了诱导晶化处理。测定了结晶膜的椭偏谱。利用多层膜模型与Ｂｒｕｇｇｅｍａｎ有效介质近似（Ｂ－ＥＭＡ）分析了结晶膜的微结构特性。研究表明：低能量密度辐照形成的结晶层需用含有ａ－Ｓｉ：Ｈ的ＥＭＡ混合物表征，说明其结晶度相对较低；而高能量密度辐照形成的结晶层，因基结晶度较高，可用不含ａ－Ｓｉ：Ｈ的ＥＭＡ混合物表征。在结晶膜与衬底之是形成了互混层，其     

PECVD法生长的nc－Si：H膜电导率的研究

使用ＰＥＣＶＤ方法生长了ｎｃ－Ｓｉ：Ｈ膜，Ｘ射线衍射、Ｒａｍａｎ光谱和电镜观测表明样品具备了纳米结构特征。测量了样品在７７Ｋ～４００Ｋ温度范围的电导率，并使用二相随机分布有效介质理论，计算了ｎｃ－Ｓｉ：Ｈ膜中晶粒部分和晶界部分的电导率。对计算结果进行了理论分析，初步探讨了ｎｃ－Ｓｉ结构对其导电性能的影响，提出ｎｃ－Ｓｉ：Ｈ的高电导率来源于膜中纳米晶粒的小尺寸效应。     

纳米硅薄膜制备技术进展

本文综述了纳米硅薄膜制备新技术的进展。着重介绍了高氢稀释硅烷蚀刻法，微波氢基团增强化学气相沉积，逐层法和高频数值等离子体化学气相沉积技术制备纳米硅薄膜的沉积过程和生长机制．本文指出氢基团为各项新技术发展的关键并将在今后纳米硅薄膜制备技术发展中起重要作用。     

Nc-Si:H薄膜器件的研究

介绍了氢化纳米硅(nc-Si:H)薄膜在电子学器件和光电转换器件(如隧道二极管、异质结二极管、变容二极管、单电子晶体管、太阳能电池、发光二极管)等方面的研究进展,分析了这些器件的性能与nc-Si:H薄膜结构之间的关系,阐述了新型器件的优点.     

Highly reflective nc-Si:H/a-CNx:H multilayer films prepared by r.f. PECVD technique

Multilayer thin films consisting of a-CN_x:H/nc-Si:H layers prepared by radio-frequency plasma enhanced chemical vapour (r.f. PECVD) deposition technique were studied. High optical reflectivity at a specific wavelength is one of major concern for its application. By using this technique, a-CN_x:H/nc-Si:H multilayered thin films (3-11 periods) were deposited on substrates of p-type (111) crystal silicon and quartz. These films were characterized using ultra-violet-visible-near infrared (UV-Vis-NIR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field effect scanning electron microscopy (FESEM) and AUGER electron spectroscopy (AES). The multilayered films show high reflectivity and wide stop band width at a wavelength of approximately 650 ± 60 nm. The FTIR spectrum of this multilayered structure showed the formation of Si-H and Si-H₂ bonds in the nc-Si:H layer and CC and N-H bonds in a-CN_x:H layer. SEM image and AES reveal distinct formation of a-CN_x:H and nc-Si:H layers in the cross section image with a decrease in interlayer cross contamination with increasing number of periods.     

Preferred growth of nanocrystalline silicon in boron-doped nc-Si:H Films

Preferred growth of nanocrystalline silicon (nc-Si) was first found in boron-doped hydrogenated nanocrystalline (nc-Si:H) films prepared using plasma-enhanced chemical vapor deposition system. The films were characterized by high-resolution transmission electron microscope, X-ray diffraction (XRD) spectrum and Raman Scattering spectrum. The results showed that the diffraction peaks in XRD spectrum were at 2θ≈47° and the exponent of crystalline plane of nc-Si in the film was (2 2 0). A considerable reason was electric field derived from dc bias made the bonds of Si-Si array according to a certain orient. The size and crystalline volume fraction of nc-Si in boron-doped films were intensively depended on the deposited parameters: diborane (B₂H₆) doping ratio in silane (SiH₄), silane dilution ratio in hydrogen (H₂), rf power density, substrate's temperature and reactive pressure, respectively. But preferred growth of nc-Si in the boron-doped nc-Si:H films cannot be obtained by changing these parameters.     

Conductivity Properties of Phosphorus-doped Hydrogenated Nanocrystalline Silicon Film

1-IntroductionInordert0applythehydr0genatednan0crys-tallineSifilm(nc-Si:H)t0futureelectricaldevices,itisnecessarytofurtherimproveitselectricproperties.Accordingt0aSi:Hdopingtechnique,thedepositionofnc-Si:P:Hfilmwasstudiedandprimaryresults0fconductivityarerep0rted.2.ExperimentalAfterexperiments,followingparameterswerechosent0dep0sitnc-Si:P:Hfilms.Thegaseousphosphorus-dopingc0ncentrati0n(PH3/SiH4)is10-`~1;dilutionratio0fsaline(SiH4/H2)is0.1%~1%,substratetemperatureisfrom15O"Cto250"C.Th…     

Role of argon in hot wire chemical vapor deposition of hydrogenated nanocrystalline silicon thin films

Structural, optical and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) films, deposited from silane (SiH₄) and argon (Ar) gas mixture without hydrogen by hot wire chemical vapor deposition (HW-CVD) method were investigated. Film properties are carefully and systematically studied as a function of argon dilution of silane (R_Ar). We observed that the deposition rate is much higher (4-23 Å/s) compared to conventional plasma enhanced chemical vapor deposited nc-Si:H films using Ar dilution of silane (0.5-0.83 Å/s). Characterization of these films with Raman spectroscopy revealed that Ar dilution of silane in HW-CVD endorses the growth of crystallinity and structural order in the nc-Si:H films. The Fourier transform infrared spectroscopic analysis showed that with increasing Ar dilution, the hydrogen bonding in the films shifts from di-hydrogen (Si-H₂) and (Si-H₂)_n complexes to mono-hydrogen (Si-H) bounded species. The hydrogen content in the films increases with increasing Ar dilution and was found to be < 4 at.% over the entire range of Ar dilutions of silane studied. However, the band gap shows decreasing trend with increase in Ar dilution of silane and it has been attributed to the decrease in the percentage of the amorphous phase in the film. The microstructure parameter was found to be > 0.4 for the films deposited at low Ar dilution of silane and ~ 0.1 or even less for the films deposited at higher Ar dilution, suggesting that there is an enhancement of structural order and homogeneity in the film. From the present study it has been concluded that the Ar dilution of silane is a key process parameter to induce the crystallinity and to improve the structural ordering in the nc-Si:H films deposited by the HW-CVD method.     

双纳米硅p层优化非晶硅太阳能电池

采用等离子体增强化学气相沉积(Plasma Enhanced Chemical Vapor Deposition,PECVD)技术在高功率密度、高反应气压和低衬底温度下制备出不同氢稀释比RH的硅薄膜.高分辨透射电镜(High-Resolution Transmission Electron Microscopy,HRT...     

Plasma enhanced chemical vapor deposition of nanocrystalline silicon films from SiF4-H2-He at low temperature

A high degree of crystallinity is obtained in nc-Si:H films deposited by r.f. PECVD, produced from SiF₄-H₂-He mixtures. The amorphous-to-nanocrystalline transition is favored because of the presence of F atoms, which preferentially etch the amorphous phase. The addition of He to the SiF₄-H₂ gas mixture gives an increase of F and H atoms in the plasma, thus inducing higher crystallinity. A further improvement in the nc-Si:H film structure and properties is obtained by adjusting the r.f. power and the deposition temperature. Under optimized plasma conditions, substrate temperatures as low as 120°C can be reached for the deposition of nc-Si:H having 100% of crystallinity.     

Effects of hydrogen atmosphere on pulsed-DC sputtered nanocrystalline Si:H films

Hydrogenated nanocrystalline silicon (nc-Si:H) films were prepared by a pulsed-DC magnetron sputtering method under an atmosphere of hydrogen/argon mixture. The effects of hydrogen concentration on the structural and electrical properties of the films were systematically investigated using grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, and conductivity measurement. A threshold hydrogen concentration of about 70% was found necessary before any crystallinity was detectable. The deposition rate decreased monotonically with increasing hydrogen concentration, while the conductivity varied with crystallite size. The abnormally low conductivity level of these nc-Si:H films was due to the extraordinarily high defect density, which was attributed both to the enhanced ion bombardment from the pulsed-DC plasma and to the oxygen contamination from the target.