低功率MPCVD制备金刚石薄膜

通过微波等离子体化学气相沉积(MPCVD)法,以CH₄/H₂为气源,合成高质量金刚石薄膜,在150 W低微波功率下,从衬底预处理方法、沉积气压、流量比等方面对制备高质量金刚石薄膜的工艺参数进行研究。结果表明:高流量比不利于金刚石颗粒的粒径控制,二次形核的存在可以获得近纳米级颗粒尺寸的金刚石薄膜;较大的沉积气压有利于制备致密均匀的金刚石薄膜;衬底预处理对薄膜的有效沉积影响明显,其中利用含金刚石粉末的甲醇悬浊液进行超声处理是最有效的种晶方法。      

磁控溅射和退火制备ZnO/SiO2复合薄膜

采用射频磁控溅射和退火处理的方法在单晶硅衬底上制备了ZnO/SiO2复合薄膜,利用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)和接触角测量等测试手段研究溅射气压、溅射功率、氧氩比和退火温度等对复合薄膜成分组成、组织结构及润湿性能的影响。研究表明,复合薄膜中主要有ZnO、SiO2、Zn2SiO4 3种物相,且分别以六方纤锌矿结构、无定形态和硅锌矿型等形式存在。随着溅射和退火工艺的改变,复合薄膜的接触角在41°～146°间变化,组织形态由颗粒状向纳米竹叶状变化。溅射气压0.5 Pa,溅射功率120 W,氧氩比(O2∶Ar)为0∶30,退火温度为700℃的条件下获得具有六方纤锌矿结构的ZnO纳米组织,该组织呈现出竹叶状,在薄膜表面交错排列形成了无序多空隙的微观形貌,使复合薄膜具有超疏水性,接触角为146°。     

金刚石表面石墨烯的制备及应用研究进展

近年来,在绝缘衬底表面生长石墨烯已经成为研究者关注的重点,出现许多新的策略,也在SiO₂/Si、蓝宝石、GaN、玻璃等多种绝缘衬底上进行尝试并取得一定进展。金刚石用作生长石墨烯的衬底具有不可代替的优异特性,但目前在金刚石衬底上直接生长石墨烯的研究较少。本文介绍目前在金刚石衬底上生长石墨烯的研究进展及相应器件的应用技术,展望金刚石衬底上制备石墨烯的发展前景。      

不同氧源对原子层沉积ZnO薄膜的性能影响

采用原子层沉积方法(ALD)分别以H2O、H2O2和O3为氧源制备ZnO薄膜,研究不同氧源对ZnO薄膜生长速率、成分、晶体结构及电学性能的影响.结果表明,采用不同氧源均能实现ZnO薄膜的ALD自限制生长,所制备ZnO薄膜均具有垂直于衬底表面的c轴择优取向.与采用H2O2和H2O为氧源制备的ZnO薄膜相比,XRD和XPS测试证实O3为氧源制备薄膜的晶体质量和Zn/O原子较高;相应的Hall测试表明其电阻率最低为0.053 Ω·cm,此时载流子浓度为4.8×1018 cm-3,Hall迁移率为24.5 cm2/Vs.     

磁控溅射制备ZnO缓冲层薄膜的微观结构和光学性能

研究了衬底温度、溅射气压对磁控溅射沉积ZnO缓冲层薄膜的微观结构、表面形貌和光学性能的影响。结果表明,衬底温度、溅射气压对ZnO缓冲层薄膜表面形貌、晶粒尺寸、禁带宽度和光学透过率等有较大影响。综合分析得出最佳的制备ZnO缓冲层薄膜的工艺为250℃、0.6 Pa。在此工艺下制备的ZnO缓冲层薄膜具有很好的ZnO(002)面c轴择优取向,结构致密、尺寸均匀,禁带宽度为3.24 eV,可见光平均透过率为86.93%,符合作CIGS太阳能电池缓冲层的要求。     

预沉积ZnO薄膜对ZnO−MoS2/ZnO复合涂层结构与性能影响

目的 通过优化原子层沉积工艺获取不同厚度ZnO薄膜,研究ZnO薄膜晶体取向对ZnO?MoS2涂层生长结构的影响,获得具有优异摩擦学性能的ZnO?MoS2/ZnO复合涂层。方法 采用原子层沉积法在不锈钢基体上预沉积不同厚度的ZnO薄膜,再用射频磁控溅射技术继续沉积ZnO?MoS2涂层,制备ZnO?MoS2/ZnO固体润滑复合涂层。结果 X射线衍射分析发现,预沉积ZnO薄膜有诱导后续ZnO?MoS2涂层沉积生长的作用,预沉积100 nm厚ZnO薄膜的ZnO?MoS2/ZnO复合涂层显示出宽化的MoS2 (002)馒头峰,其截面形貌显示为致密的体型结构,获得的摩擦因数最低(0.08),纳米硬度最高(2.33 GPa),硬度/模量比显示该复合涂层的耐磨损性能得到提升;X射线光电子能谱分析结果表明,复合涂层表面游离S与空气中水发生反应程度大约为原子数分数5%,显示复合涂层耐湿性能较好;基于原子层沉积ZnO薄膜生长及其对后续ZnO?MoS2涂层生长的影响分析,提出了ZnO?MoS2/ZnO复合涂层磨损模型,阐明了ZnO薄膜对复合涂层结构及摩擦学性能的影响,并以该模型解释了200 nm厚 ZnO薄膜上沉积ZnO?MoS2涂层出现的摩擦因数由高到低的变化趋势及最终磨损失效现象。结论 合适的原子层沉积制备的ZnO薄膜有利于MoS2 (002)取向生长,可有效提升ZnO?MoS2/ZnO复合涂层的摩擦学性能;控制ZnO薄膜厚度,可实现ZnO薄膜与基底及ZnO?MoS2层间界面之间的优化结合,以制得具有较好摩擦学性能及使用寿命的ZnO?MoS2/ZnO复合涂层。     

Si(100)衬底上(110)取向La_(2/3)Sr_(1/3)MnO_3薄膜的制备与性能

用脉冲激光沉积法在Si(100)衬底上制备了(110)择优取向的La2/3Sr1/3MnO3薄膜,研究了环境氧压对薄膜结晶度、取向、表面形貌和微结构的影响。结果表明:10Pa氧压下沉积的薄膜具有高结晶度的(110)择优取向,晶粒分布均匀,晶粒分布均匀,表面均方根粗糙度Rrms为1.35 nm。与无明显择优取向的薄膜相比,(110)择优取向的La2/3Sr1/3MnO3薄膜具有较高的饱和磁化强度(Ms)、金属-绝缘体相变温度(TM-I)和较低的电阻率(ρ)。     

高纯、高度[100]择优取向金刚石薄膜

采用独特的形核-刻蚀-生长-刻蚀-生长…循环沉积工艺,用微波等离子体化学气相沉积(MWPCVD)法制备出了高纯、高度[100]择优取向的金刚石薄膜.SEM和XRD分析表明得到的膜材具有很高的[100]择优取向性;Raman光谱和SEM对照分析证实膜材的金刚石相组成纯净度高,是高纯、高度[100]择优取向的织构金刚石薄膜.暗电流I-V特性测试结果表明,这种薄膜的电阻率达到1014数量级以上,比常规工艺制备的膜高近两个数量级,是一种性能优良的电子薄膜材料.理论分析表明,薄膜电阻率大幅度提高的原因在于膜层中非金刚石相含量的显著减少.     

Ni-Al辅助微波自蔓延烧结制备Ti3SiC2基金刚石复合材料工艺研究

为降低金刚石磨削工具的制造成本和能耗,探寻一种在低能耗下实现高性能陶瓷结合剂金刚石磨具的制备工艺,同时研究助燃剂Si和金刚石粒度等因素对样品物相组成、显微形貌和磨削性能的影响。采用Ti、Si、石墨粉和金刚石磨料作为原料,经冷压成型至生胚,通过Ni-Al辅助在微波场加热诱发Ti-Si-C体系发生自蔓延高温合成(SHS)反应以制备Ti₃SiC₂基金刚石复合材料。结果表明,高热值Ni-Al合金辅助可以缩短样品的烧结时间,还可以将诱发SHS反应的温度点控制在金刚石石墨化温度以下。在Ar保护气氛下,Ti-Si-C体系发生SHS反应,可生成Ti₃SiC₂、TiC和Ti₅Si₃等3种物相。随Si含量升高,Ti₃SiC₂相先增多后减少,当n (Ti):n (Si):n (C)=3∶1.1∶2时,复合材料的磨削性能最佳,磨耗比最高可达286.53。分析不同原料配比下的试样磨耗比差异的产生机制,认为基体组织中存在微小且分布均匀的气孔...     

高纯、高度[100]择优取向金刚石薄膜

采用独特的形核-刻蚀-生长-刻蚀-生长…循环沉积工艺，用微波等离子体化学气相沉积（MWPCVD）法制备出了高纯、高度[100]择优取向的金刚石薄膜。SEM和XRD分析表明得到的膜材具有很高的[100]择优取向性；Raman光谱和SEM对照分析证实膜材的金刚石相组成纯净度高，是高纯、高度[100]择优取向的织构金刚石薄膜。暗电流Ⅰ-Ⅴ特性测试结果表明，这种薄膜的电阻率达到10H数量级以上，比常规工艺制备的膜高近两个数量级，是一种性能优良的电子薄膜材料。理论分析表明，薄膜电阻率大幅度提高的原因在于膜层中非金刚石相含量的显著减少。     

二氧化碳对金刚石膜生长的影响

利用微波等离子体化学气相沉积法,以H₂/CH₄/CO₂为混合气源,在Si基底上沉积金刚石膜,分析了微波功率和CO₂对金刚石膜生长的影响。利用Raman光谱、扫描电子显微镜（SEM）和X射线衍射（XRD）表征金刚石膜,以得到样品质量、表面形貌、晶粒取向等信息。结果表明:适当提高微波功率,可以促进金刚石晶粒长大并提高（100）取向度;加入适量CO₂,能提高金刚石膜质量和生长速率,并保持表面形貌不会发生明显变化,但随着CO₂含量的增加,金刚石表面形貌发生较大变化,薄膜质量和沉积速率先提高后降低。      

From diamond to crystalline silicon carbonitride: effect of introduction of nitrogen in CH4/H2 gas mixture using MW-PECVD

Microwave plasma enhanced chemical vapor deposition (MW-PECVD) is considered as one of the most successful growth techniques in recent diamond and crystalline carbon nitride investigations. In this study, we tried to synthesize crystalline carbon nitride film using MW-PECVD by gradually increasing the content of nitrogen into H₂/CH₄ gas mixture. Well-faceted crystalline diamond films could be synthesized with a H₂/CH₄ gas ratio of 198:2. With the gradual increase of nitrogen content up to 3% in the gas mixture diamond film quality deteriorates seriously, and the morphological crystal size and growth rate of diamond coatings decreased significantly. With the nitrogen gas content increased to approximately 6–22%, a lot of separated round diamond or diamond-like carbon particles formed on the surface rather than a continuous film. Only with the nitrogen content increased above 72%, could some tiny crystals with a type of hexagonal facet form on the silicon surface, together with many large, round diamond particles. With the further increase of nitrogen gas content above 90%, many large, well-faceted hexagonal crystals formed on Si surface. However, XRD, energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy and nano-indentation analysis indicated that these crystals were actually silicon carbonitride (Si–C–N) with a crystalline structure of Si₃N₄ modified with the introduction of carbon atoms, rather than carbonitride as expected and regarded.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

Resistance of polyimide/silica hybrid films to atomic oxygen attack

Polyimide/silica (PI/SiO₂) hybrid films were prepared by the sol–gel process to improve the erosion resistance of polyimide materials in atomic oxygen (AO) environments. The p-aminophenyltrimethoxysilane (APTMOS) was used as a coupling agent to enhance the compatibility between the PI and SiO₂. The effects of the APTMOS addition on the morphology and property of the PI/SiO₂ hybrids were investigated using UV–Vis spectrophotometer, FTIR spectroscopy and SEM. The thermal properties and AO resistance of the PI/SiO₂ hybrids were investigated by TGA and in the AO simulator, respectively. The results showed that the addition of APTMOS remarkably reduced the size of the silica particles, the PI/SiO₂ hybrid films became transparent, and the compatibility between the PI and SiO₂ and the thermal stability of the hybrids were significantly improved. During AO exposure, a passive inorganic SiO₂ layer was formed on the PI/SiO₂ hybrid films, causing the hybrid films to possess excellent AO resistance. The optical properties of the PI/SiO₂ hybrid films were not altered after AO exposure.     

Correlation between dielectric properties and strain in Pb0.5 Sr0.5TiO3 thin films prepared by using the sol–gel method

Pb_0.5Sr_0.5TiO₃ (PST) thin films were fabricated by the alkoxide-based sol–gel process using spin-coating method on Pt/Ti/SiO₂/Si substrate. The PST films annealed from 500 °C to 650 °C for 1 h show a perovskite phase and dense microstructure with a smooth surface. The grain size and dielectric constant of PST films increase with the increase in annealing temperature, which reduces the SiO₂ equivalent thickness of the PST film. The crystallinity or internal strain in the PST thin films analyzed from the diffraction-peak widths correlates well with the decrease in the dielectric losses. The dielectric constants and dielectric loss (%) of the PST films annealed at 650 °C (t_eq=0.89 nm) were 549 and 0.21%, respectively.     

Er-doped SiO2–Al2O3 thin films prepared by the sol–gel route

The synthesis of homogeneous and pure silica–alumina binary glasses doped with rare-earth (RE) ions such as Er³⁺ is currently a key challenge for the development of integrated optics devices such as lasers, optical amplifiers or waveguides. In this study Er³⁺-doped SiO₂–Al₂O₃ films were prepared by the sol–gel route. Aluminium sec-butoxide, Al(O-sec-C₄H₉)₃ (ASB), and tetraethoxysilane, Si(OC₂H₅)₄ (TEOS), were used as glass oxide precursors, whereas erbium was introduced as Er(NO₃)₃. The alumina content in the silica matrix was 10 at.%, while erbium doping ranged between 200 and 5000 ppm. The preparation of the starting sol–gel solution and the layer deposition by a dip-coating procedure were performed in dry-box under nitrogen atmosphere. The obtained films were subsequently annealed in air between 300 and 1000 °C. After treatment at 500 °C, layers 200 nm thick were obtained. The composition, microstructure and surface morphology of the films were investigated by X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), glancing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). Crack-free, transparent, high purity films were obtained, characterised by compositional and microstructural homogeneity.     

TC4合金表面扩散渗硅涂层的高温氧化行为和失效机制

为提高钛合金的高温抗氧化性能,采用固体粉末扩散渗方法在其表面制备了扩散渗硅涂层,研究了涂层的组织结构、高温氧化行为和失效机制。结果表明,所制备涂层具有致密的多层梯度组织结构,主要由TiSi₂外层,TiSi中间层和Ti₅Si₄+Ti₅Si₃内层组成。高温氧化实验结果表明,涂层在850℃空气中氧化时表面形成了由SiO₂和TiO₂混合组成的保护膜,高温抗氧化性能优良;氧化过程中,涂层与基体合金中Si和Ti的互扩散引起氧化膜内TiO₂含量增加及Si源不足,导致氧化膜保护性变差;氧化产物与涂层之间较高的P-B比、氧化膜与涂层组织间热膨胀系数不匹配导致了氧化膜开裂和剥落。     

纳米金刚石膜真空窗口的制备

使用自制的微波等离子体化学气相沉积装置,以乙醇为碳源在（100）硅表面制备了金刚石膜;然后用浓硝酸和氢氟酸的混合溶液腐蚀硅,制备出金刚石膜窗口。使用场发射扫描电镜（SEM）、X射线衍射、拉曼光谱（Raman）、原子力显微镜（AFM）表征和分析金刚石膜,并以自制的漏气率测量系统测量金刚石膜窗口的漏气率。结果表明:金刚石膜的厚度为15 μm,平均粗糙度值R_a为39.5 nm,晶粒的尺寸大小为30 nm,漏气率为8.8×10-9 Pa·m3/s。