微波等离子体化学气相沉积法低温制备直纳米碳管膜

Among the three main methods for the synthesis of carbon nanotubes (CNTs)， chemical vapor deposition (CVD) has received a great deal of attention since CNTs can be synthesized at significantly low temperature. Plasma chemical vapor deposition methods can synthesize CNTs at lower temperature than thermal CVD. But in the usual catalytic growth of CNTs by CVD， CNTs are often tangled together and have some defects. These will limit the property research and potential applications. How to synthesize the straight CNTs at low temperature becomes a challenging issue. In this letter， straight carbon nanotube (CNT) films were achieved by microwave plasma chemical vapor deposition (MWPCVD) catalyzed by round Fe-Co-Ni alloy particles on Ni substrate at 610℃. It was found that， in our experimental condition， the uniform growth rate along the circumference of round alloy particles plays a very important role in the growth of straight CNT films. And because the substrate is conducting， the straight CNT films grown at low temperature may have the benefit for property research and offer the possibility to use them in the future applications.     

Precise Control of Metal Oxide Thin Films Deposition in Magnetron Sputtering Plasmas for High Performance Sensing Devices Fabrication

Magnetron sputtering deposition is a widely used technique to deposit thin film precisely at nanoscale level. During the deposition of metal oxide thin films, reactive oxygen gas is introduced into the deposition chamber. Pure metal and metal oxide materials can be used as sputter target, although the simplest way is by using a pure metal target. In such reactive process, the effect of target poisoning significantly influence the deposition process and the growth mechanisms of metal oxide thin films became very complex. In general, external parameters such as discharge power, working pressure, reactive gases ratio and substrate temperature are used to optimize the properties of deposited thin films. Then, ex-situ analyses such as scanning electron microscope and X-ray diffraction analysis are performed to obtain the optimized parameter. Sample depositions and ex-situ analyses consume time to achieve the goal through try and error. In this article, in-situ plasma diagnostics are reviewed focusing on an optical emission spectroscopy to precisely control and investigate the sputter target poisoning effect during the deposition of metal oxide thin films. The emission of atomic lines from several metal and oxygen atoms were used to discuss the deposition mechanisms and their correlation with the deposited thin films was observed. Finally, the deposited metal oxide thin films were proposed and tested for several applications such as gas sensor and frequency selective surface glass.     

Deposition of Ethylene-Hexafluoropropene Gradient Plasma-Copolymer Using Dielectric Barrier Discharge Reactor at Atmospheric Pressure: Application to Release Coatings on Pressure-Sensitive Tape

Plasma-polymerized hexafluoropropene (PPHFP) film deposited using a dielectric barrier discharge reactor at atmospheric pressure had low enough adhesive strength, 22.2 Nm^–1, for use as a release coating of pressure-sensitive adhesive tapes, but the bond strength between PPHFP film and a poly (ethylene terephthalate) (PET) substrate film was slightly weak: some part of the PPHFP deposits could be peeled from the PET substrate. Since the XPS results indicated that the bond strength between plasma-polymerized ethylene (PPE) film and PET substrate was strong enough, we tried to deposit PPE and plasma-polymerized ethylene - hexafluoropropene gradient plasma-copolymer between the PET substrate and the PPHFP film. This multi-layer film (MLF) had low enough adhesive strength, 36.6 Nm^–1, for use as the release coating; this value was near that of a control sample, Teflon sheet, 21.6 Nm^–1. Moreover, the bond strength between MLF and PET substrate became stronger than that between PPHFP and PET films.     

Diamond Deposition on Substrates with Different Geometries in a Thermal Plasma Reactor

The effects of process parameters on diamond film deposition have been considered in an atmospheric-pressure dc thermal plasma jet reactor. Two different precursor injection systems have been evaluated, counterflow and side injection. The precursor flow rate using ethanol has been found to strongly affect crystal size as well as orientation of crystal growth planes. Further, crystal size on sharp edges has been found to be up to five times larger than on planar surfaces. The effects of substrate geometry on the morphology and area of deposited diamond have been investigated as well. The results of this study show that dc thermal plasma jets can provide high diamond deposition rates, for example on wires and drills, although crystal size and film thickness show substantial variation.     

低温等离子体转化NO/O2/N2气氛中NO的实验研究

通过建立低温等离子体实验系统, 研究了介质阻挡放电型低温等离子体反应器作用于NO/O2/N2混合气体系时, NO, O2初始浓度对NO的转化效率的影响以及NOx, O3浓度随能量密度的变化关系. 低温等离子体作用于NO/O2/N2混合气体系时, NO同时发生氧化还原反应, 氧化反应占主导地位, 大部分NO转化为NO2; NO转化率随O2, NO初始浓度增大而降低, 能量密度在450～600 J/L时转化率较高; 产生的O3浓度随能量密度的增大呈先增后减的趋势.     

电泳沉积法制备V2O5薄膜的结构和性能

V2O5 thin films were successfully prepared on ITO substrate with electrophoresis deposition (EDP) through V2O5 sol. X-ray diffraction and scanning electron microscopy were used for studying the structure of the films. The optical and electrochemical properties were measured by the transmittance spectra and cyclic voltammetry measurements, respectively. It is found that V2O5 thin films deposited by EDP are a compact microstructure with finer adhesive force with ITO substrate and the thickness is uniform. During the cycle experiment, the films exhibited reversible two-color (yellow at oxidation and green at reduction) with a maximum transmittance change of around 30%. Moreover, the films had an excellent cycle for lithium intercalation/deintercalation and good cycle stability, the cycle efficiency for the 50th cycle was 88.02% and the films still had fine adhesive force with ITO substrate with no dissolving over more than 50 cycles. The Li+ diffusion coefficient in V2O5 thin film was 5.10×10-12 cm2/s by the electrochemical impedance spectra method. All results indicate that V2O5 thin films by the electrophoresis deposition may be suitable for the use in the electrochromic devices.     

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O2 As a Molecular Probe

Encapsulation methods have shown to be effective in imparting improved stability to metal-halide perovskite nanocrystals (NCs). Atomic layer deposition (ALD) of metal oxides is one of the promising approaches for such encapsulation, yet better control on the process parameters are required to achieve viable lifetimes for several optoelectronic and photocatalytic applications. Herein, we optimize the ALD process of amorphous aluminum oxide (AlO_x) as an encapsulating layer for CsPbBr₃ NC thin films by using oxygen (O₂) as a molecular diffusion probe to assess the uniformity of the deposited AlO_x layer. When O₂ reaches the NC surface, it extracts the photogenerated electrons, thus quenching the PL of the CsPbBr₃ NCs. As the quality of the ALD layer improves, less quenching is expected. We compare three different ALD deposition modes. We find that the low temperature/high temperature and the exposure modes improve the quality of the alumina as a gas barrier when compared with the low temperature mode. We attribute this result to a better diffusion of the ALD precursor throughout the NC film. We propose the low temperature/high temperature as the most suitable mode for future implementation of multilayered coatings.     

Phase Diagram at Low Temperature of the System ZrO2/Nb2O5

Various compositions of the ZrO₂/Nb₂O₅ system were synthesized and the experimental conditions for obtaining reproducible results were established. The gel was precipitated at constant pH = 10, aged at room temperature for 18 h and, after filtration, dried at 110 °C for 24 h. The phase diagram of the ZrO₂/Nb₂O₅ system was established between 600 and 1300 °C. Phase transitions of ZrO₂ and Nb₂O₅ were observed with XRD; and two ternary compounds, 6 ZrO₂ · Nb₂O₅ and 12 Nb₂O₅ · ZrO₂, were identified. The samples with a Nb₂O₅ content between approximately 10 and 40 mole% showed the greatest specific area and are thus best for use as catalyst supports.     

微波等离子体辅助化学气相沉积法低温合成定向碳纳米管阵列

自碳纳米管被发现以来[1] ,这种准一维纳米新材料由于其优异的力学、电学、储氢等理化性质而显示出非常重要的理论研究与实际应用价值[2 ,3] .碳纳米管阵列更可作为场致发射器件 ,有望应用于冷阴极平板显示器或纳米电子学等前沿领域[4 ] ,成为碳纳米管研究中的热点 .在已有报道的多种制备碳纳米管阵列的方法中 ,以孔性硅或孔性 Al2 O3作为模板剂 ,通过化学气相沉积制备的方法较为普遍[5～ 7] ,但此类方法往往需要在较高温度 (高于 70 0℃[6 ,7] )下进行 ,对于碳纳米管阵列最诱人的应用前景之一平板显示器而言 ,要求在显示玻璃表面直接生长…     

脉冲激光沉积LiMn2O4薄膜的研究

在氧气氛下采用355nm脉冲激光烧蚀制备了LiMn₂O₄薄膜,并用四极质谱和发光光谱技术考察了脉冲激光烧蚀过程及环境氧气对薄膜沉积过程的影响.质谱测定结果表明,355nm激光烧蚀LiMn₂O₄的产物主要有Li⁺、Mn⁺等离子和O₂、O、LiO₂、LiMnO、MnO及锂原子的多聚体等中性产物.不同氧气压下测定的发光光谱表明烧蚀原子在环境氧气氛中存在氧化过程.用循环伏安法和X射线衍射法对薄膜进行了表征.     

Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films

Introduction Inorganic oxide films have attracted a lot of interest in the last several decades. Among them, silicon dioxide films are widely used in modern microelectronics, optics and mechanics. This material has been grown by various methods including thermal oxidation, chemical vapor phase deposition, plasma-enhanced chemical vapor phase deposition, and so on.1,2 Recently, Nagayama et al.3 have reported that SiO2 thin films could be produced by a new chemical method of liquid phase depos…     

脉冲激光沉积CuF2薄膜的电化学性能

采用脉冲激光沉积法在不锈钢基片上制备了纳米结构的CuF2薄膜, 其充放电性能显示该薄膜具有540 mAh·g-1可逆容量, 对应于每个CuF2可与2.0个Li发生反应. 其循环伏安特性显示在2.2和2.8 V (vs Li/Li+)处出现了一对新的氧化还原峰. 充放电后薄膜的组成与结构通过非原位高分辨电子显微和选区电子衍射来表征. 结果揭示了纳米结构CuF2薄膜的电化学反应机理, LiF在过渡金属Cu的驱动下可以发生可逆的分解和形成.     

金属铝诱导法低温制备多晶硅薄膜

以氢气稀释的硅烷(SiH₄)和硼烷(B₂H₆)为气源,利用等离子体增强化学气相沉积法(PECVD)制备出p型a-Si薄膜.采用铝诱导晶化技术对不同厚度的铝膜对a-Si薄膜晶化的影响进行了研究.实验中发现,铝膜溅射为10 s的非晶硅薄膜样品在450℃下退火10 min后,p型a-Si结构仍为非晶态,铝膜溅射为20 s的非晶硅薄膜在450℃下退火20 min后,p型a-Si薄膜开始晶化为poly-Si薄膜,并且铝膜厚度越厚,则a-Si薄膜晶化程度越强.     

Preparation of the In2O3·Sn Films by MO-CVD Technique

Introduction In₂O₃·Sn films have high transparency(>95％) within the visible spectral region, low resistivity(10^-2-10^-4 ohm·cm) at room temperature and superior thermal stability. These films have been applied to solar cells, electronics and photoelectronics fields. In recent years, organometallic-CVD method has emerged as a successful alternate to the physical methods and general CVDfor the growth of these films.     

Modeling of H2 and H2/CH4 Moderate-Pressure Microwave Plasma Used for Diamond Deposition

One-dimensional transport models of moderate-pressure H ₂ and H ₂ /CH ₄ plasmas obtained in a diamond deposition microwave reactor are presented. These models describe the plasma as a thermochemically nonequilibrium flow with three different energy modes. The solution of the one-dimensional plasma transport equations enabled the estimation of plasma species concentrations and temperatures on the axis of the reactor. As far as pure H ₂ plasmas are concerned, results showed that the model predictions of gas and vibration temperatures are in good agreement with experimental measurements. The model also yields a relatively good qualitative prediction of the variations of H-atom mole fraction with the power density absorbed by the plasma. The results obtained for H ₂ /CH ₄ discharges showed that the model prediction on the variations of H-atom mole fraction with methane percentage in the discharge is in good qualitative agreement with experimental results. They also showed that methane is rapidly converted to acetylene before reaching the discharge zone. The concentrations of neutral hydrocarbon species in the reactor are mainly governed by thermal chemistry. The addition of methane strongly affects the ionization kinetics of the plasma. Three major ions are generally obtained in H ₂ /CH ₄ plasmas: C ₂ H ₂ ⁺ , C ₂ H ₃ ⁺ , and C ₂ H ₅ ⁺ . The relative predominance of these ions depends on the considered plasma region and on the discharge conditions. The ionic species concentrations are also mainly governed by chemistry, except very near the substrate surface. Finally the use of this transport model along with the surface chemistry model of Goodwin ⁽¹⁾ enabled us to estimate the diamond growth rate for several discharge conditions.     

微波辅助化学浴快速沉积Eu:YVO4薄膜

应用简单有效的微波辐射辅助化学浴技术快速沉积了Eu：YVO4纳米颗粒膜．所沉积的Eu：YVO4薄膜均匀、密实、镜面．产物用x射线衍射仪、原子力显微镜、紫外分光光度计和荧光分光光度计进行测试、表征和分析．结果表明所得Eu：YVO4薄膜由纳米颗粒组成,具有高的(200)择优取向,结晶性良好,在紫外光激发下具有良好的荧光发射性能．     

Atomic Layer Deposition of Ternary Indium/Tin/Aluminum Oxide Thin Films,Their Characterization and Transistor Performance under Illumination.

Multilayered heterostructures comprising of In₂O₃, SnO₂, and Al₂O₃ were studied for their application in thin-film transistors (TFT). The compositional influence of tin oxide on the properties of the thin-film, as well as on the TFT characteristics is investigated. The heterostructures are fabricated by atomic layer deposition (ALD) at 200 °C, employing trimethylindium (TMI), tetrakis(dimethylamino)tin (TDMASn), trimethylaluminum (TMA), and water as precursors. After post-deposition annealing at 400 °C the thin-films are found to be amorphous, however, they show a discrete layer structure of the individual oxides of uniform film thickness and high optical transparency in the visible region. Incorporation of only two monolayers of Al₂O₃ in the active semiconducting layer the formation of oxygen vacancies can be effectively suppressed, resulting in an improved semiconducting and switching behavior. The heterostacks comprising of In₂O₃/SnO₂/Al₂O₃ are incorporated into TFT devices, exhibiting a saturation field-effect mobility (μ_sat) of 2.0 cm² ⋅ V⁻¹ s⁻¹, a threshold-voltage (V_th) of 8.6 V, a high current on/off ratio (I_On/I_Off) of 1.0×10⁷, and a subthreshold swing (SS) of 485 mV ⋅ dec⁻¹. The stability of the TFT under illumination is also altered to a significant extent. A change in the transfer characteristic towards conductive behavior is evident when illuminated with light of an energy of 3.1 eV (400 nm).     

PE-CVD of Fluorocarbon/SiO Composite Thin Films Using C4F8 and HMDSO

Plasma copolymerization of hexamethyldisiloxane (HMDSO,(CH₃)₃-Si-O-Si-(CH₃)₃) and C₄F₈ was performed using an RF plasma enhanced chemical vapor deposition method for application to low dielectric constant intermetal dielectrics. Structure of the films was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The film composition was controlled gradually from fluorinated carbon to organic siloxane by changing the mixing ratio of HMDSO/Ar. Dielectric constant of the films ranged from 2–3.3. Thermal stability of the films, which was characterized by intensity loss of IR absorbance peak around 1000–1500 cm^–1 corresponding to C-F _n , Si-O-Si and Si-(CH₂)_n-Si bonds, was inferior to that from C₂F₄/HMDSO/Ar. In situ gasphase FT-IR spectroscopy revealed that there was a marked difference between the gas phase of C₄F₈/HMDSO/Ar and that of C₂F₄/HMDSO/Ar discharges. The IR spectrum of the former combination plasma contained a peak at 1250 cm^–1 with full width at half maximum as large as 150 cm^–1, which suggests that fluorocarbon particles and/or dusts are formed in the plasma. This suggests also that deposition precursors are not only CF _n (n = 1, 2, and 3) but also larger precursors such as C _x F _y (x > 1, y < 2x + 2) in C₄F₈/HMDSO/Ar discharges, which is presumably the cause of difference in thermal stability of the films prepared from C₄F₈/HMDSO/Ar and C₂F₄/HMDSO/Ar mixtures.     

微波加热制备PS/SiO2复合纳米微球及其摩擦性能研究

用微波加热法合成了表面功能化的聚苯乙烯／SiO2复合纳米粒子,分别用FTIR、TEM及TGDTA对其结构和形貌进行了表征,并考察了其摩擦学性能。结果表明,微波辐射能使反应时间大大缩短。在所选择的实验条件下,可制备出以SiO2纳米微粒为核,PMMA、PS为壳层的核壳结构复合纳米微球,微球粒径约15nm,颗粒较均匀,并且在有机溶剂中有良好的分散性,作为润滑油添加剂,具有良好的抗磨性能。     

脉冲激光沉积GeO2薄膜的电化学性能

采用脉冲激光沉积法在不锈钢基片上制备了GeO₂薄膜。充放电性能显示其具有高达1 336 mAh·g^-1可逆容量，这相当于每个GeO₂可与5.1个Li发生反应。其循环伏安特性显示在1.2 V和0.4 V处出现一对新的氧化还原峰。充放电后薄膜的组成与结构通过非原位高分辨电子显微和选区电子衍射来表征。结果显示在外电场作用下，Ge能够可逆地驱动Li₂O分解和形成。这是金属氧化物的一种新的电化学反应机理。