PECVD生长nc—Si：H膜的沉积机理分析

ｎｃ－Ｓｉ：Ｈ膜具有显著不同α－Ｓｉ：Ｈ与μｃ－Ｓｉ：Ｈ膜的新颖结构与物性。从热力学反应的基元过程出发，定性地分析了本征ｎｃ－Ｓｉ：Ｈ与掺磷ｎｃ－Ｓｉ（Ｐ）：Ｈ膜的沉积机理，并提出了进一步改善膜层质量的新途径。     

复合光导层液晶光阀的研究

介绍了一种具有柱状结构的a-Si：H／nc—Si复合光导层的液晶光阀，复合光导层是通过热蒸发和等离子体辉光放电沉积方法，采用Al诱导a-Si：H制成的。经过测试，这种柱状结构薄膜具有电导各向异性，其横向电导率小于纵向电导率。用这种薄膜制成的液晶光阀其分辨率达到5001p／inch。     

非晶硅光敏材料的高电阻率化研究

本文研究了用于制造非晶硅感光鼓的高阻非晶硅光敏材料，通过微量掺Ｂ、Ｏ，控制ａ－Ｓｉ：Ｈ薄膜中的ＳｉＨ２和ＳｉＨ基团的组成比，有效地实现了非晶硅材料的高电阻率化，其暗电阻率ρｄ≥１０＾１３Ω·ｃｍ，在可见了光至近红外光范围内，具有很高的单色光电导增益，σｐｈ／σｄ≥１０＾３。分析了ａ－Ｓｉ：Ｈ［Ｂ、Ｏ］材料ＩＲ谱的特征，说明了氧原子和硅－氢基团对微结构的影响及其在支配非晶硅光电性能方面的重要作用。     

铁电液晶光寻址空间光调制器特性测试与分析

通过实验对一只美国某大学最新研制的新型高速空间光调制器──氢键非晶硅铁电液晶（ａ－Ｓｉ：Ｈ／ｐｉｎ／ＦＬＣ）光寻址空间光调制器（ＯＡＳＬＭ）的几个关键性能参数进行了测试并分析讨论。结果，此器件分辨率达４０ｌｐ／ｍｍ，对比度为２０∶１，响应上升时间为３．２ｍｓ，响应下降时间为２．６ｍｓ，光学灵敏度为５ｐＪ（写入光源λ＝６３３ｎｍ）。这种器件所表现出的高速、高分辨率和低功耗特性使之在光计算和光学信息处理领域中具有很大的应用潜力。     

a—Si：H薄膜结构对晶硅薄膜性能的影响

用ａ－Ｓｉ：Ｈ薄膜经退火晶化成的多晶硅薄膜,其晶化温度、晶粒尺寸的电性能薄膜的初始结构有密切关系,而ａ－Ｓｉ：Ｈ薄膜的切初结构依赖于沉积条件,用ＰＣＶＤ方法高速沉积的ａ－Ｓｉ：Ｈ薄膜,经５５０℃的低温退火,可以制备平均晶粒尺寸为几面ｎｍ,最大晶粒尺寸为２μｍ,电导率为１．６２（Ω．ｃｍ）＾－１的优质多晶硅薄膜。     

氮对纳米硅氮薄膜品化的影响

在电容式耦合等离子体化学气相沉积系统中，用高氢稀释硅烷和氮气为反应气氛制备纳米硅氮（ｎｃ－ＳｉＮｘ：Ｈ）薄膜结果表明：当Ｎ＿２／ＳｉＨ＿４气体流量比（Ｘｎ）从１增加为４时，薄膜的晶态年从５８％降至１４％，晶粒尺寸从１０ｎｍ降至５ｕｍ，Ｎ／Ｓｉ含量比从０．０３增至０．１２．当Ｘｎ≥５，则生成非晶硅氮（ａ－ＳｉＮｘ：Ｈ）薄膜．当Ｘｎ从１增加为１０时，薄膜暗电导率从１０￣（－５）（Ωｃｍ）￣（－１）降至１０￣（－１１）（Ωｃｍ）￣（－１），具有逾渗行为，这与薄膜的晶态率紧密相关．     

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     

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。     

氮对纳米硅氮薄膜晶化的影响

在电容式耦合等离子体化学气相沉积系统中，用高氢稀释硅烷和氮气为反应气氛制备纳米硅氮（ｎｃ－ＳｉＮｘ２Ｈ）薄膜，结果表明，当Ｎ２／ＳｉＨ４气体流量比（Ｘｎ）从Ｉ增加为４时，薄膜的晶态率从５８％降至１４％，晶粒尺寸从１０ｎｍ降至５ｎｍ，Ｎ／Ｓｉ含量比从０．０３增至０．１２，当Ｘｎ≥５，则生成非晶硅氮（ａ－ＳｉｕＮｘ２Ｈ）薄膜，当Ｘｎ从１增加为１０时，薄膜暗电导率从１０＾－５（Ωｃｍ）＾－１降至１０＾－     

非晶硅碳合金(a-SiCx:H)薄膜的进展

从制备方法,结构特征和光电性能等各方面介绍了氢化非晶硅碳合金（ａ－ＳｉＣｘ：Ｈ）薄膜这种重要的半导体材料,对其发展现状及前景进行了综述。并对近年来出现的纳米硅碳（ｎｃ－ＳｉＣｘ：Ｈ）薄膜的发展状况作了专门评述。     

Effects of a a-Si:H layer on reducing the dark current of 1310 nm metal-germanium-metal photodetectors

Two approaches of hydrogenated-amorphous-silicon (a-Si:H), as Schottky-barrier height (SBH) enhancement and passivation layers, were investigated to suppress dark current of 1310 nm metal-germanium-metal photodetectors (MGM-PDs). Observations show that when a-Si:H is inserted between metal and Ge, the dark current is effectively reduced due to SBH enhancement, but similarly lowers photocurrent resulting from the blocking of a-Si:H. In contrast with a-Si:H acting as a passivation layer a very high photo-to-dark current ratio of 6530 is achieved with a high responsivity of 0.72 A/W, attributing to the defect centers on the Ge surface which are passivated. Such a result suggests that the a-Si:H passivation layer is a good candidate in fabricating high-quality 1310 nm MGM-PDs.     

a-Si∶H及其多层膜光致发光某些性质的研究

本文研究了 a-Si∶H 及 a-Si∶H/a-SiN_x∶H 多层膜光致发光的某些性质。实验研究表明,a-Si∶H 及其多层膜的光致发光峰值能量强烈地依赖于沉积偏压、a-Si∶H 层厚度和内应力,并对这些结果进行了讨论。     

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.     

Nanocrystalline silicon thin films on PEN substrates

We study the structural and electrical properties of intrinsic layer growth close to the transition between amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H), deposited on glass and PEN without intentional heating. These samples showed different behaviour in Raman shift and XRD spectra when compared with that of samples deposited at 200 °C. Electrical properties of these films also reflect the transition between a-Si:H and nc-Si:H, and put in evidence some differences between the microstructure of the films grown on PEN and on glass.P- and n-doped layers were deposited onto glass substrate without intentional heating and at 100 °C with thicknesses ranging from 1000 nm to 35 nm. Conductivity measurements indicate the capability of doping this material, but, for very thin layers, substrate heating was found to be essential.     

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.     

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…     

Thermal stability of Al/nanocrystalline-Si bilayers investigated by in situ heating energy-filtered transmission electron microscopy

In situ heating energy-filtered transmission electron microscopy was employed to investigate the interfacial intermixing/reactions during thermal annealing of Al/nanocrystalline-Si (nc-Si) bilayers in the temperature range of 150–500 °C. In comparison with the Al/amorphous-Si (a-Si) bilayer, the Al/nc-Si bilayers were found to be much more stable against thermal annealing. Wetting and c-Si growth processes along Al grain boundaries, which take place during annealing of Al/a-Si bilayers, do not occur in Al/nc-Si bilayers, because of the lack of thermodynamic driving forces in the latter case. As a consequence, also in contrast with Al/a-Si bilayers, no layer exchange occurs in Al/nc-Si bilayers, not even after annealing at 500 °C. Instead, intermixing of Al/nc-Si is realized at the Al/nc-Si interface by the formation of Al spikes growing into the nc-Si sublayers at temperatures higher than 300 °C. The relatively low Al-spike formation temperature in Al/nc-Si systems, as compared with that for Al/single-crystalline Si systems, is ascribed to the higher Gibbs energy of nanocrystalline Si as compared to single-crystalline Si.     

Determination of band offsets in a-Si:H/c-Si heterojunctions from capacitance-voltage measurements: Capabilities and limits

The capabilities and limitations of the well-known C-V technique for the determination of the conduction band offsets in (n)a-Si:H/(p)c-Si heterojunctions are presented. In particular, the effects due to the presence of an inversion layer in c-Si and a non-negligible defect density at the a-Si:H/c-Si interface on the reliability of the C-V intercept method are discussed. The influence of the Fermi level positions in (p)c-Si and (n)a-Si:H on the inversion layer formation and the influence of the interface defect density have been analysed using numerical simulations and experimental measurements.     

Analysis of single junction a-Si:H solar cells grown on different TCO’s

In consequence of previous investigation of individual transparent conductive oxide (TCO) and absorber layers a study was carried out on hydrogenated amorphous silicon (a-Si:H) solar cells with diluted intrinsic a-Si:H absorber layers deposited on glass substrates covered with different TCO films. The TCO film forms the front contact of the super-strata solar cell and has to exhibit good electrical (high conductivity) and optical (high transmittance) properties. In this paper we focused our attention on the influence of using different TCO’s as a front contact in solar cells with structure as follows: Corning glass substrate/TCO (800, 950 nm)/p-type μc-Si:H (∼5 nm)/p-type a-Si:H (10 nm)/a-SiC:H buffer layer (∼5 nm)/intrinsic a-Si:H absorber layer with dilution R = [H₂]/[SiH₄] = 20 (300 nm)/n-type a-Si:H layer (20 nm)/Ag + Al back contact (100 + 200 nm). Diode sputtered ZnO:Ga, textured and non-textured ZnO:Al [3] and commercially fabricated ASAHI (SnO₂:F) U-type TCO’s have been used. The morphology and structure of ZnO films were altered by reactive ion etching (RIE) and post-deposition annealing.It can be concluded that the single junction a-Si:H solar cells with ZnO:Al films achieved comparable parameters as those prepared with commercially fabricated ASAHI U-type TCO’s.     

Optimization of n nc-Si:H and a-SiNx:H layers for their application in nc-Si:H TFT

The n-type doped silicon thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) technique at high and low H₂ dilutions. High H₂ dilution resulted in n⁺ nanocrystalline silicon films (n⁺ nc-Si:H) with the lower resistivity (ρ ∼0.7 Ω cm) compared to that of doped amorphous silicon films (∼900 Ω cm) grown at low H₂ dilution. The change of the lateral ρ of n⁺ nc-Si:H films was measured by reducing the film thickness via gradual reactive ion etching. The ρ values rise below a critical film thickness, indicating the presence of the disordered and less conductive incubation layer. The 45 nm thick n⁺ nc-Si:H films were deposited in the nc-Si:H thin film transistor (TFT) at different RF powers, and the optimum RF power for the lowest resistivity (∼92 Ω cm) and incubation layer was determined. On the other hand, several deposition parameters of PECVD grown amorphous silicon nitride (a-SiN_x:H) thin films were changed to optimize low leakage current through the TFT gate dielectric. Increase in NH₃/SiH₄ gas flow ratio was found to improve the insulating property and to change the optical/structural characteristics of a-SiN_x:H film. Having lowest leakage currents, two a-SiN_x:H films with NH₃/SiH₄ ratios of ∼19 and ∼28 were used as a gate dielectric in nc-Si:H TFTs. The TFT deposited with the NH₃/SiH₄∼19 ratio showed higher device performance than the TFT containing a-SiN_x:H with the NH₃/SiH₄∼28 ratio. This was correlated with the N−H/Si−H bond concentration ratio optimized for the TFT application.