Luminescence properties of terbium-doped SiCN thin films by rf magnetron reactive sputtering

Terbium-doped SiCN (SiCN:Tb) thin films were deposited by rf magnetron reactive sputtering at 800 °C. The as-prepared samples were characterized by XRD, FTIR, and XPS. The results showed that SiCN:Tb films mainly contained both SiC and Si₃N₄ nano-compositions with complicated chemical bond networks. Photoluminescence measurements indicated that the undoped SiCN films exhibited a blue-green light emission, while SiCN:Tb films emitted a strong green one. The SiC nanocrystallites formed in the undoped SiCN films might be responsible for the blue-green light emission, while the formed quaternary Si-C-Tb-O compositions in the doped samples could account for the strong green PL behaviors.     

SiCN扩散阻挡层薄膜的制备及特性研究

采用磁控溅射法在单晶硅衬底上制备了SiCN及Cu/SiCN薄膜,并对试样进行了退火处理.利用原子力显微镜(AFM)、X射线衍射(XRD)、四探针测试仪(FPP)研究了SiCN薄膜的表面形貌、物相结构及在Cu/SiCN/Si结构中SiCN薄膜对铜与硅的阻挡性能.结果表明,沉积态SiCN薄膜为无定型的非晶结构,晶化温度在1000℃以上;SiCN薄膜作为Cu的扩散阻挡层有较好的热稳定性及阻挡性,阻挡失效温度在600℃左右.     

SiCN薄膜的制备及其性能研究

利用射频溅射法在Si衬底上制备了SiCN薄膜，并利用X射线衍射（XRD）、红外吸收谱（FTIR）和X射线光电子谱（XPS）对薄膜的结构、成份及化学键合状态进行了分析。结果表明，室温制备的SiCN薄膜为非晶状态，并形成了Si-C、Si-N和C－N键；而在高温下（衬底温度为800℃），薄膜中含有SiCN的晶体成分。此外，还利用原子力显微镜（AFM）对薄膜的表面形貌进行了研究，并进一步研究了样品的场发射性能。在场强为24V／μm时，最大发射电流可达3.3mA/cm^2。     

Dielectric and mechanical properties of hot-pressed SiCN/Si3N4composites

A series of high temperature radar wave-absorbing materials, SiCN/Si₃N₄ceramics, were prepared by hot-pressing. The nanometer SiCN powder, used as an absorber in the SiCN/Si₃N₄ceramic, was synthesized through laser pyrolysis of ((CH₃)₃Si)₂NH) and NH₃. The dielectric and mechanical properties of the prepared ceramics were investigated. XRD and SAED were conducted to study the growth of crystals in the ceramics. The results showed that the transformation of Si₃N₄from α to β was inhibited. The growth of the rod-like β -Si₃N₄grains in SiCN/Si₃N₄ceramics was retarded during hot-pressing process due to the existence of the nanometer SiCN particles. The relative density and the strength of the composites both decreased with the increase of the SiCN content in the composites. The dielectric properties of the ceramics prepared at different temperatures were very different. For the samples sintered at 1600^∘C and 1700^∘C, both the real and imaginary parts of the complex permittivity of them increased as the content of SCN powder in the sample obviously. For the sample with same concentration of SCN, the real and imaginary parts of them varied with the sintering temperature. SAED pattern revealed that structure of the SiCN in SiCN/Si₃N₄sintered at 1800^∘C tended to crystallize fully. Its real, imaginary parts and dissipation factor were much lower than those sintered at 1600^∘C and 1700^∘C greatly. Supported by national natural science foundation of China (No. 50572090)     

高温吸波涂层的制备及其力学性能研究

以BaO-La2O3-B2O3系玻璃为粘结剂,S iCN纳米吸收剂作为添加剂,采用热压粘涂法在钛合金板表面制备了一系列涂层。文中分析了BaO-La2O3-B2O3系玻璃的性能,探索了粘涂工艺和S iCN纳米粉含量对涂层抗拉强度的影响机理。结果表明含有吸收剂的涂层粘接强度低于不含吸收剂的涂层,由于涂层内存在S iCN纳米粉团聚现象,拉伸时趋于内聚破坏,而界面的结合则比较致密。随着吸收剂含量的增加,涂层的抗拉强度明显降低。     

SiCN/Sialon复合材料的制备及微波介电性能研究

以AlN、Al2O3和Y2O3为添加剂，用无压烧结法制备了SiCN／Sialon复合材料。研究表明，在相同烧结条件下，随着纳米SiCN含量的增加，材料的烧结致密度下降。XRD结果表明，SiCN／Sialon复合材料由主晶相β—Sialon（Si3Al3O3N5）和极少量的SiO3、β—SiC组成。SEM研究表明，随着纳米SiCN含量的增加，材料中棒状的β—Sialon（Si3Al3O3N5）含量明显减少。抗弯强度研究表明，β—Sialon（Si3Al3O3N5）复合材料的抗弯强度随着纳米SiCN含量的升高而降低，从纯Sialon陶瓷的530MPa下降到含22．26％SiCN时的196MPa，其原因是由于随着纳米SiCN含量的增加，材料的致密度降低，β—Sialon（Si3Al3O3N5）含量减少所致。SiCN／Sialon复合材料复介电常数的实部和虚部均随纳米SiCN含量的升高而增大，但是低于预期值，其原因是由于长时间高温烧结时，纳米SiCN结构发生变化，其复介电常数的实部和虚部大幅度下降造成。     

C~+注入a-SiN_x∶H的原子化学键合的研究

常温下对低压化学气相沉积制备的纳米硅镶嵌结构的a-SiNx∶H薄膜进行C 注入,能量为30keV,剂量为2×1017cm-2.对C 注入的SiNx薄膜在800℃的温度下,进行2h的常规炉退火处理.通过XPS,AES的测量得到,经800℃高温退火处理后的薄膜形成了部分SiCxNy结构.用喇曼、XPS等分析手段对薄膜结构及成分进行了测量与分析,得到不同退火温度对离子注入形成SiCN薄膜结构与成分的影响,认为高温退火后薄膜中硅含量与SiCxNy薄膜的形成有重要的关系.     

Enhanced electric conductivity of polymer‐derived SiCN ceramics by microwave post‐treatment

The effect of microwave treatment on the electric conductivity and structure of a polymer‐derived SiCN ceramic is studied. It is found that the conductivity of the microwave‐treated sample is about 40 times higher than that of the conventional heat‐treated one at the same temperature and dwell time conventionally. The X‐ray diffraction patterns show that both samples are amorphous without obvious crystallization. Raman analysis reveals that the microwave‐treated sample exhibited a narrower full width at half maximum and upper‐shift of G peak. X‐ray photoelectron spectroscopy spectra show that there is a significant sp³‐to‐sp² transition of free carbon in the microwave‐treated sample. These results suggest that the microwave‐treatment can induce a distinct structure evolution of the free carbon, which contributes to the remarkable enhancement of the conductivity of the sample.     

Evaluation of the elastic-plastic properties of SiCN coating system by finite element simulations

The elastic properties of SiCN coating on substrates can be evaluated by nano-indentation test, however, it is challenging for experiments to evaluate the plastic performance of SiCN coating. Finite element (FE) is a numerical method for investigating in-depth mechanical behavior of various structures. In this paper, a contact model between Berkovich indenter and SiCN/Si system is established by FE method. The stress-strain behavior of SiCN coating is obtained by comparing the calculated P-h curves with experimental results. The indentation depth dependent elastic modulus and hardness of the SiCN coating are calculated from the P-h curves and are close to the experimental data. When the indentation depth is in excess of 10% of the coating thickness, the mechanical properties of SiCN coating tend to be influenced by the Si substrate, which also consists with experiments. The proposed approach provides an efficient tool to predict the mechanical properties of SiCN coating.