氮气退火对氟化非晶碳膜结构和电学性能的影响

采用电子回旋共振等离子体化学气相淀积(ECR-CVD)方法以C4F8和CH4为源气体制备了氟化非晶碳(a-C:F)膜并在氮气气氛中对a-C:F膜进行了退火处理研究.X光电子能谱(XPS)化学结构分析表明,退火后a-C:F膜中CF3,CF2和CF含量减少,而C-CFx(x=1～3)交联结构增多.电学性能研究指出,退火后a-C:F薄膜的介电常数由于电子极化和薄膜密度的增大而上升,Al/a-C:F/Si结构的阻滞效应由于界面态密度下降而减弱,同时a-C:F膜的π-π*带隙和电荷陷阱能量减小并导致薄膜漏电流增大.     

ECR-CVD沉积a-C:F薄膜

采用电子回旋共振等离子体化学气相沉积（ECR－CVD）技术,用苯和三氟甲烷混合气体,制备了氟化非晶碳膜（a-C:F)。用红外吸收光谱（FTIR）和X射线光电子能谱（XPS）分析了a-C:F薄膜的结构。FTIR结果表明,氟主要以C－F,CF2的形式成键形成a-C:F薄膜,XPS结果进一步证明a-C:F膜中存在C－F,CF2键,获得了与FTIR相一致的结果。     

a-C:F薄膜结构与电学性能研究

采用电子回旋共振等离子体化学气相沉积（ECR-CVD）方法,以C4F8和CH4为源气体,在不同气体流量比R（R=[CH4]/（[CH4]＋[C4F8]））条件下沉积氟化非晶碳（a-C：F）薄膜.用原子力显微镜（AFM）分析了薄膜的表面形貌.用柯西（Cauchy）模型和Levenberg-Marquardt非线性迭代算法分析了薄膜的椭圆光谱.用X光电子能谱（XPS）和傅里叶变换红外光谱（FTIR）技术分析了薄膜的化学成分.随着气体流量比R的增大a-C：F薄膜C-C键结构增多,薄膜C/F比增大.a-C：F薄膜的介电常数取决于电子极化并随R的增大而上升.a-C：F薄膜导电行为在低场强区域呈现欧姆特性,在高场强区域符合Poole-Frankel机制.随着C-C含量的增大,π价带态和π＊导带态之间的带隙减小,电荷陷阱深度减小,陷阱中的电子在场增强热激发作用下更容易进入导带,导致薄膜漏电流增加.     

非平衡磁控溅射沉积TiC／a—C多层膜的组织结构

本文采用非平衡磁控溅射沉积技术,分别以石墨和甲烷气体为碳源,制备TiC／a-C多层膜。利用Ⅺ射线衍射仪、透射电子显微镜、俄歇电子能谱仪和拉曼光谱仪等实验手段对所沉积的TiC／a—C多层膜的组织形态、结构及成份进行了分析。结果表明：所制备的两种TiC／a-C薄膜中,TiC的晶粒呈柱状生长;用溅射石墨靶方法获得的TiC／a-C薄膜,无明显的层状结构,a-C相为石墨化和非石墨化的碳原子构成,碳原子的有序化程度较大;而采用甲烷气体为碳源沉积的TiC／a—C薄膜,呈规则的分层结构,碳原子的有序化程度低。采用过渡层及添加适当的金属元素能改善膜／基的结合强度。     

铝基SiOx膜层滑动磨损及其机理研究

本文采用低温常压CVD方法制备铝基SiOx陶瓷膜层.以黄铜为对磨材料,使用销-盘式磨损试验机对比研究纯铝表面与SiOx膜层的滑动磨损性能,通过SEM分析磨损的表面形貌并分析其磨损机理.结果表明纯铝表面发生粘着磨损,存在大量塑性变形和折叠,导致片状脱落,磨损率高;SiOx薄膜硬度较高,存在孔隙,表面发生塑性变形、崩塌和磨粒磨损;因薄膜孔隙具有储存润滑剂(水)的作用,磨损率明显低于对比纯铝样品;随沉积时间增加,SiOx膜层变厚,承载能力提高,磨损量减小.     

掺氮类金刚石薄膜的微观结构和电导特性

用射频等离子体化学气相沉积法（RFCVD）和CH4、N2与Ar组成的混合气体制备掺氮类金刚石薄膜（a-C:H:N)。用原子力显微镜（AFM）,俄歇电子能谱（AES）,红外光谱（IR）以及显微拉曼谱（Micro-Raman)对a-C:H:N薄膜的表面形貌、组分和微观结构进行了表征。实验结果表明,薄膜中有纳米量级的颗粒存在,而且随反应气体中N2与CH4比值的增大,薄膜中氮元素的含量也随之增大,并主要以C-N键和N-H键形式存在,少量以C≡N键形式存在,还研究了热退火对a-C:H:N薄膜的电导率的影响。     

ECR-CVD制备氟化非晶碳低k介质薄膜

采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法,以C4F8和CH4为源气体在不同气体流量比R(R=[CH4]/{[CH4] [C4F8]})条件下成功地沉积了氟化非晶碳(a-C:F)低介电常数(低k)材料.采用X光电子能谱和椭圆光谱方法分析了a-C:F薄膜的化学组分和光学性质.沉积的a-C:F薄膜介电常数约为2.1～2.4,热稳定性优于350℃.随着气体流量比的增大,沉积a-C:F薄膜中的碳含量增大,CF、CF2、CF3含量减少,C-C交链成分增加,从而使得π-π(*)吸收增强,并引起薄膜光学带隙下降.氮气气氛下350℃温度退火后应力释放引起a-C:F薄膜厚度变化,变化量小于4%.450℃温度退火后,由于热分解作用薄膜厚度变化量在30%左右.     

低红外发射率TiO2/AgxCU1-x/Ti/TiO2纳米多层膜

利用磁控溅射制备了银含量在100％至80％之间的单层银铜合金薄膜和TiO2／AgxCu-1x／Ti／TiO2：纳米四层膜。利用x射线衍射、扫描电子显微镜、扫描俄歇微探针，分光光度计、红外发射率测量仪对样品进行表征，研究了单层金属膜和多层膜的光学、电学性质随着银含量的变化以及热处理前后薄膜性能的变化。结果表明：相同厚度的合金膜，随着Ag含量的降低，导电性能下降，Ag含量低于80％的合金已不适合作为多层膜的金属层；1500C大气下热处理30min，纯银薄膜性质发生明显变化，明视透过率下降10％，方块电阻由2．5W／口增加至18W／□，红外发射率由0．17增加到0．69。AgCu合金薄膜性质未发生明显变化。方块电阻相近的TiO2／AgxCu1-x／Ti／TiO2纳米多层膜，经250℃大气下热处理40min后，TiO2／Ag／Ti／TiO2和TiO2／Ag80Cu20／Ti／TiO2纳米多层膜的性质变化较小，热稳定性较好，其余的多层膜性质发生较大变化，红外发射率显著增加。     

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。     

氟化非晶碳膜的光学带隙和伏安特性

用苯（C6H6）和三氟甲烷（CHF3）混合气体源气体，采用永磁微波电子回旋共振等离子体化学气相沉积（MWECRCVD）技术，制备了氟化非晶碳膜（a-C:F)，光学带隙的结果表明它与膜中的C，F元素含量和键结构都有关系，伏安特性的测量表明a-C:F薄膜的电导在低电场下呈欧姆特性，高电场下则是肖特基发射机制。     

Micron-sized fracture experiments on amorphous SiOx films and SiOx/SiNx multi-layers

In this study miniaturized monolithic cantilevers of thermally grown silicon oxide and multi-layer cantilevers of plasma enhanced chemical vapor deposited silicon oxide and nitride were mechanically characterized. In order to determine the fracture stress as well as the fracture toughness, un-notched and focused ion beam pre-notched cantilevers were tested. While the thickness of the monolithic cantilevers was varied from 280 nm to 2380 nm, the individual sub-layer thickness of the multi-layer cantilevers was adjusted to 50 nm. Bending experiments reveal a small increase of the fracture stresses with decreasing cantilever thicknesses. For the multi-layer stacks the tensile stress at fracture slightly exceeds the strength values of the corresponding monolithic materials. Furthermore, it is demonstrated that the specimens pre-notched by focused ion beam do not show significant changes in fracture toughness with varying pre-notch size. This makes the applied test a reproducible technique to determine fracture toughness of brittle films.     

Effects of thickness and deposition rate on the optical absorption properties of co-evaporated Mn/SiOx, Cr/SiOx and Cu/SiOx thin films

Abstracts are not published in this journal     

Electroforming in MIM structure of SiOx and SiOx/SnO composite dielectric thin films

Electroforming and related phenomena in SiO _x and SiO _x -SnO thin films incorporated in copper-oxide-copper metal-insulator-metal structures have been investigated. Both types of devices showed voltage-controlled negative resistance, voltage memory effects (thermal and threshold) and electron emission. The voltage-controlled negative resistance and voltage memory effects may be interpreted in terms of the filamentary model of Dearnaley et al. The electron emission phenomenon is attributed to the Dearnaley model as modified by Rakhshani et al. The a.c. conductance of the devices before and after forming was also studied and the results support the proposed filamentary model of the electroforming process.     

水热法制备Ge/SiOx纳米电缆

以混合的氧化锗粉和硅粉为原料，采用水热法在高温高压下制备出具有核-壳同轴结构的Ge／SiOx纳米电缆。扫描和透射电镜研究表明这种Ge／SiOx纳米同轴电缆的产量高，直径分布均匀，长度可达微米级，并证实其为非晶态SiOx包裹Ge内核的核-壳结构。Ge芯线沿着[211]方向生长。Ge／SiOx纳米同轴电缆的生长过程遵循气-液-固和氧化物辅助生长机制，与原料中GeO2与Si的比率有关。     

Carbon Microstructure Dependent Li-Ion Storage Behaviors in SiOx/C Anodes

SiO_x anode has a more durable cycle life than Si, being considered competitive to replace the conventional graphite. SiO_x usually serves as composites with carbon to achieve more extended cycle life. However, the carbon microstructure dependent Li-ion storage behaviors in SiO_x/C anode have received insufficient attention. Herein, this work demonstrates that the disorder of carbon can determine the ratio of inter- and intragranular Li-ion diffusions. The resulted variation of platform characteristics will result in different compatibility when matching SiO_x. Rational disorder induced intergranular diffusion can benefit phase transition of SiO_x/C, benefiting the electrochemical performance. Through a series of quantitative calculations and in situ X-ray diffraction characterizations, this work proposes the rational strategy for the future optimization, thus achieving preferable performance of SiO_x/C anode.     

SiOx/PET复合薄膜的力学性能及阻隔性能

目的基于氧化硅(SiO_x)镀层优异的性能,研究不同厚度的SiO_x层对SiO_x/PET复合薄膜力学性能和阻隔性能的影响,以期得到性能较优的SiO_x/PET复合薄膜。方法以自制的聚对苯二甲酸乙二醇酯(PET)薄膜为基材,采用等离子体增强化学气相沉积法沉积得到SiO_x层厚度分别为40,150,230,320 nm的SiO_x/PET复合薄膜,并进行傅里叶变换红外线光谱分析、力学性能和阻隔性能测试,以及薄膜表观形貌分析。结果沉积SiO_x层后,SiO_x/PET复合薄膜拉伸强度和断裂伸长率随SiO_x层厚度的增大先增大后减小,氧气透过率和水蒸气透过率则出现明显衰减而后逐渐平缓的趋势。SiO_x层厚度达150~230 nm时,复合薄膜的力学性能和阻隔性能表现较优,拉伸强度、断裂伸长率、氧气透过率以及水蒸气透过率分别提高了约25.0%,20.9%,79.3%,77.3%。结论适宜厚度的SiO_x层可以使得SiO_x/PET复合薄膜同时具备较优的力学性能和阻隔性能。     

Growth of nickel silicides in Si and Si/SiOx core/shell nanowires

We exploited the oxide shell structure to explore the structure confinement effect on the nickel silicide growth in one-dimensional nanowire template. The oxide confinement structure is similar to the contact structure (via hole) in the thin film system or nanodevices passivated by oxide or nitride film. Silicon nanowires in direct contact with nickel pads transform into two phases of nickel silicides, Ni31Si12 and NiSi2, after one-step annealing at 550 °C. In a bare Si nanowire during the annealing process, NiSi2 grows initially through the nanowire, followed by the transformation of NiSi2 into the nickel-rich phase, Ni31Si12 starting from near the nickel pad. Ni31Si12 is also observed under the nickel pads. Although the same phase transformations of Si to nickel silicides are observed in nanowires with oxide confinement structure, the growth rate of nickel silicides, Ni31Si12 and NiSi2, is retarded dramatically. With increasing oxide thickness from 5 to 50 nm, the retarding effect of the Ni31Si12 growth and the annihilation of Ni2Si into the oxide confined-Si is clearly observed. Ni31Si12 and Ni2Si phases are limited to grow into the Si/SiOx core-shell nanowire as the shell thickness reaches 50 nm. It is experimental evidence that phase transformation is influenced by the stressed structure at nanoscale.     

Constructing Biomass-Based Ultrahigh-Rate Performance SnOy@C/SiOx Anode for LIBs via Disproportionation Effect

To break the stereotype that silica can only be reduced via a magnesiothermic and aluminothermic method at low-temperature condition, the novel strategy for converting silica to SiO_x using disproportionation effect of SnO generated via low-temperature pyrolysis coreduction reaction between SnO₂ and rice husk is proposed, without any raw materials waste and environmental hazards. After the low-temperature pyrolysis reaction, SnO_y@C/SiO_x composites with unique structure (Sn/SnO₂ dispersed on the surface and within pores of biochar as well as SiO_x residing in the interior) are obtained due to the exclusive biological properties of rice husk. Such unique structural features render SnO_y@C/SiO_x composites with an excellent talent for repairing the damaged structure and the highly electrochemical storage ability (530.8 mAh g⁻¹ at 10 A g⁻¹ after 7500 cycles). Furthermore, assembled LiFePO₄||SnO_y-50@C/SiO_x full cell displays a high discharge capacity of 463.7 mAh g⁻¹ after 100 cycles at 0.2 A g⁻¹. The Li⁺ transport mechanism is revealed by density functional theory calculations. This work provides references and ideas for green, efficient, and high-value to reduce SiO₂, especially in biomass, which also avoids the waste of raw materials in the production process, and becomes an essential step in sustainable development.