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     

超高真空（UHV）PECVD系统沉积a—Si1—xCx：Hk薄膜及其特性

本文研究了应用新型的超高真空等离子增强化学了相沉积（ＶＨＶ－ＰＥＣＶＤ）复合腔系统 只ａ－Ｓｉ１－ｘＣｘ：Ｈｋ薄膜及其特性。系统的真空度可达１０＾－７Ｐａ（１０＾－９Ｔｏｒｒ）以上。通过控制Ｈ２对常规用混合气体（ＳｉＨ４＋ＣＨ４）的稀释程度以及相应的ＣＨ４比例,优化沉积工艺参数,制备出能带宽度范围变化较大的高质量非晶氢化硅碳（ａ－Ｓｉ１－ｘＣｓ：Ｈｋ）薄膜,通过ＲＢＳ、ＥＲＤＡ、ＩＴ和Ｒａｍａｍ光     

a—C：H（N）薄膜的慢正电子分析

采用Ｃ２Ｈ２和Ｎ２的混合气体在单晶Ｓｉ衬底上用射频－直流等离子化学气相沉积法制备ａ－Ｃ：Ｈ（Ｎ）薄膜,用Ｆｏｕｒｉｅｒ红外谱研究了ａ－Ｃ：Ｈ（Ｎ）薄膜的结构。用慢正电子湮没技术研究了类金刚石薄膜中缺陷的深度分布以及Ｎ的百分含量对薄膜中缺陷浓度和缺陷类型的影响。Ｆｏｕｒｉｅｒ红外测试结果表明,ａ－Ｃ：Ｈ（Ｎ）薄膜中氮含量随混合气体中Ｎ２百分含量的升高而增大,薄膜中碳氮原子形成Ｃ≡Ｎ键。慢正电子分析表     

掺硼对非晶碳化硅膜的影响

试验观测了掺硼对氢化非晶碳化硅膜生长速度，膜的组分，光学带隙，电导率，硬度和结合力的影响。结果证明，用等离子体分解（ＳｉＨ４和ＣＨ４）混合气体制备的α－Ｓｉ１－ｘＣｘ：Ｈ膜能有效的掺杂。硼掺杂可改变光学带隙，电导率和硬度。退火可增加薄膜的硬度和结合力。     

rf—dc PECVD制备的a—C：H（N）薄膜的结构分析

采用射频－直流等离子增强化学气相沉积技术用Ｃ２Ｈ２和Ｎ２气的混合气体制备出ａ－Ｃ：Ｈ（Ｎ）薄膜,用ＴＥＭ、红外谱、ＸＰＳ等多种分析测试手段研究了薄膜的结构。结果表明ａ－Ｃ：Ｈ（Ｎ）薄膜中Ｎ与Ｃ原子可形成Ｎ－Ｃ、Ｃ＝Ｎ和Ｎ≡Ｃ键,而碳氢原子主要以ＣＨ２基的形式存在。且薄膜中存在具有理想化学配比的Ｃ３Ｎ４相,薄膜的结构是由Ｃ３Ｎ４相镶嵌在非晶态ＣＮｘ基体中组成。     

反应溅射Si-C-N薄膜的结构分析

本文用射频反应磁控溅射制备了ＳｉＣＮ薄膜,对薄膜的化学成分、结构进行了研究。结果表明,反应气体Ｎ２、Ｓｉ、Ｃ三者之间形成了Ｓｉ－Ｃ,Ｓｉ－Ｎ和Ｃ－Ｎ键,构成了复杂的网络结构。成分分析表明薄膜的化学计量式近似为ＳｉＣＮ。对比分析了反应应溅射制备ＳｉＣＮ、ＣＮｘ、ＳｉＮｙ、ＳｉＣｘ薄膜的ＦＴＩＲ谱。     

薄膜晶体管a－Si：H／a－SiN_x界面研究

对比ａ－Ｓｉ：Ｈ／ａ－ＳｉＮｘ界面附近ａ－Ｓｉ：Ｈ和体材料ａ－Ｓｉ：Ｈ的光致发光谱（ＰＬ）发现：随着ＳｉＮｘ中ｘ的增大，ＰＬ峰值向低能方向移动，相对发光强度减小。这是因为由于氮含量的增加，界面晶格不匹配加剧，导致悬挂键密度增多和深能级隙态密度增加。该观点得到Ｃ－Ｖ测试结果的证实。     

rf-dc PECVD制备的a-C∶H(N)薄膜的结构分析

采用射频－直流等离子增强化学气相沉积技术用Ｃ２Ｈ２和Ｎ２气的混合气体制备出ａ－Ｃ∶Ｈ（Ｎ）薄膜,用ＴＥＭ、红外谱、ＸＰＳ等多种分析测试手段研究了薄膜的结构。结果表明ａ－Ｃ∶Ｈ（Ｎ）薄膜中Ｎ与Ｃ原子可形成ＮＣ、ＣＮ和ＮＣ键,而碳氢原子主要以ＣＨ２基的形式存在。且薄膜中存在具有理想化学配比的Ｃ３Ｎ４相,薄膜的结构是由Ｃ３Ｎ４相镶嵌在非晶态ＣＮｘ基体中组成     

常压MOCVD制备MgO薄膜的研究

本文首次报道用常压金属有机化学气相沉积（ＡＰ－ＭＯＣＶＤ）在Ｓｉ（１００），ＳｉＯ２／Ｓｉ（１００）和Ｐｔ／Ｓｉ（１００）衬底上外延高质量的ＭｇＯ薄膜。研究了衬底温度与薄膜的取向性关系和ＭｇＯ薄膜的潮解特性。高纯ｍａｇｎｅｓｉｕｍａｃｅｔｙｌａｃｅｔｏｎａｔｅ［ｂｉｓ（２，４－ｐｅｎｔａｎｅｔａｎｅ－ｄｉｏｎｏ）ｍａｇｎｅｓｉｕｍ］［Ｍｇ（ＣＨ２ＣＯＣＨ２ＣＯＣＨ３）２］作为金属有机源，扫描电镜（ＳＥＭ），透射电镜（ＴＥＭ）和Ｘ－ＲＡＹ衍射实验显示，在较低的衬底温度（～４８０℃）下一次淀积成单晶膜。薄膜均匀，致密，结晶性和取向性很好，衬底温度（Ｔｓ）在４００℃到６８０℃之间，在Ｓｉ（１００）衬底上生长的ＭｇＯ薄膜都具有［１００］取向，在Ｓｉ（１００）、ＳｉＯ２／Ｓｉ（１００）和Ｐｔ／Ｓｉ（１００）衬底上生长的ＭｇＯ薄膜也都具有［１００］取向。     

PECVD法淀积氟碳掺杂的氧化硅薄膜表征

以正硅酸乙酯（ＴＥＯＳ）和八氟环丁烷（Ｃ４Ｆ８）为原料,采用等离子体增强化学气相淀积（ＰＥＣＶＤ）方法制备了氟碳掺杂的氧化硅薄膜（ＳｉＣＯＦ）．样品的Ｘ射线光电子能谱（ＸＰＳ）和傅立叶变换红外光谱（ＦＴＩＲ）分析表明薄膜中含有Ｓｉ－Ｆ、Ｓｉ－Ｏ、Ｃ－Ｆ、Ｃ－ＣＦ_ｘ、ＣＦ₂等构型．刚淀积的薄膜的折射率约为１．４０．对暴露在空气中以及在不同温度下退火后薄膜的折射率做了测量,并对其变化机理进行了讨论,同时表明了理想的淀积温度应是３００℃．     

Properties of nanocrystalline SiC:Ge:H alloy deposited by hot-wire chemical vapor deposition using Organosilane and Organogermane

Nanocrystalline hydrogenated silicon carbide: germanium alloy (nc-SiC:Ge:H) films have been deposited by hot-wire chemical vapor deposition at a low substrate temperature of about 300 °C. Germanium incorporation into the films and film structure based on cubic silicon carbide were confirmed by X-ray photoelectron spectroscopy and X-ray diffraction. Optical absorption spectra of the films with a germanium mole fraction of about 2% shifted to lower energies by about 0.2 eV compared with that of nanocrystalline cubic silicon carbide films.     

Homogeneous nanocrystalline cubic silicon carbide films prepared by inductively coupled plasma chemical vapor deposition

Silicon carbide films with different carbon concentrations x(C) have been synthesized by inductively coupled plasma chemical vapor deposition from a SiH(4)/CH(4)/H(2) gas mixture at a low substrate temperature of 500?°C. The characteristics of the films were studied by x-ray photoelectron spectroscopy, x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared absorption spectroscopy, and Raman spectroscopy. Our experimental results show that, at x(C) = 49?at.%, the film is made up of homogeneous nanocrystalline cubic silicon carbide without any phase of silicon, graphite, or diamond crystallites/clusters. The average size of SiC crystallites is approximately 6?nm. At a lower value of x(C), polycrystalline silicon and amorphous silicon carbide coexist in the films. At a higher value of x(C), amorphous carbon and silicon carbide coexist in the films.     

Low temperature crystallization of amorphous silicon carbide thin films for p–n junction devices fabrication

Metal induced crystallization technique was used to crystallize hydrogenated amorphous silicon carbide (a-SiC:H) thin films at low temperatures. Two types of substrates, silicon and silicon carbide were considered and the substrate effects on the final crystallized film were studied. About 200 nm a-SiC:H films were deposited and crystallized successfully on n-type Si and n-type 6H SiC substrates at a temperature of 600 °C. Fourier Transform Infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) analysis confirmed the crystallization of a-SiC:H film. Current–voltage (I–V) and capacitance–voltage (C–V) measurement confirms the formation of p–n junction with rectification over five orders of magnitude from ?2 V to 2 V.     

Synthesis of β-Mo(2)C thin films

Thin films of stoichiometric β-Mo(2)C were fabricated using a two-step synthesis process. Dense molybdenum oxide films were first deposited by plasma-enhanced chemical vapor deposition using mixtures of MoF(6), H(2), and O(2). The dependence of operating parameters with respect to deposition rate and quality is reviewed. Oxide films 100-500 nm in thickness were then converted into molybdenum carbide using temperature-programmed reaction using mixtures of H(2) and CH(4). X-ray diffraction confirmed that molybdenum oxide is completely transformed into the β-Mo(2)C phase when heated to 700 °C in mixtures of 20% CH(4) in H(2). The films remained well-adhered to the underlying silicon substrate after carburization. X-ray photoelectron spectroscopy detected no impurities in the films, and Mo was found to exist in a single oxidation state. Microscopy revealed that the as-deposited oxide films were featureless, whereas the carbide films display a complex nanostructure.     

Structural changes in tungsten wire and their effect on the properties of hydrogenated nanocrystalline cubic silicon carbide thin films

We investigated the structural changes in tungsten wire heated to 1800 °C in SiH₄/CH₄/H₂/N₂ atmosphere and the effect of the aging tungsten wire on the properties of N-doped hydrogenated nanocrystalline cubic silicon carbide (nc-3C-SiC:H) thin films. The aged tungsten wire had two parts: hot parts of the middle of the wire and relatively cold parts connected to clamps. Tungsten carbide (W₂C) layer formed in the wire of the hot parts, while crystalline silicon and cubic silicon carbide (c-Si/3C-SiC) layer deposited on the wire of the cold parts. N-doped nc-3C-SiC:H thin films were deposited for 5 min (thickness: ~ 30 nm) after the tungsten wire was heated under the same condition as during the film deposition for given times (exposure time). No changes in the structural, electrical and optical properties of the nc-3C-SiC:H thin films were observed for the exposure time up to 450 min.     

Structural, electrical and optical characterization of N- and P-type SiC:H films deposited using ECR-CVD

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) method from a mixture of methane, silane and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the diborane and phosphine levels on the optical bandgap and conductivity were investigated. In the case of boron-doped films, there is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were largely amorphous and the bandgap decreases as the diborane levels are highly conductive and contains the whereas films deposited at a high microwave power of 800 W at low diborane levels are highly conductive and contains the silicon microcrystalline phase. These films become amorphous as the diborane level is increased, while the optical bandgap remains relatively unaffected throughout the entire range of diborane levels investigated. In the case of phosphorus-doped films, Raman scattering analysis showed that the deposition conditions strongly influence the structural, optical and electrical properties of the SiC:H films. Unlike boron doping, doping with phosphorus can have the effect of increasing the silicon microcrystalline phase in the SiC:H films which were prepared at low (150 W) and high (600 W) microwave powers. Films prepared at high microwave power showed only small variations in the optical bandgap, suggesting that good phosphorus doping efficiency can be achieved in films which contain the silicon microcrystalline phase (mc-SiC:H).     

Effects of the silicon-to-carbon ratio and the hydrogen content in amorphous SiC thin films prepared by reactive sputtering

Amorphous silicon carbide thin films were prepared with a wide range of composition by reactive sputtering. Rutherford backscattering and nuclear reaction analysis were used to determine the silicon, carbon and hydrogen contents in the films. The optical properties were found to depend on both the silicon-to-carbon ratio and the hydrogen content. As in amorphous silicon, it was possible to obtain a Schottky barrier between a metal (in this case gold) and amorphous silicon carbide.     

Amorphous silicon carbide thin films (a-SiC:H) deposited by plasma-enhanced chemical vapor deposition as protective coatings for harsh environment applications

We investigated amorphous silicon carbide (a-SiC:H) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) as protective coatings for harsh environment applications. The influence of the deposition parameters on the film properties was studied. Stoichiometric films with a low tensile stress after annealing (< 50 MPa) were obtained with optimized parameters. The stability of a protective coating consisting of a PECVD amorphous silicon oxide layer (a-SiO_x) and of an a-SiC:H layer was investigated through various aging experiments including annealing at high temperatures, autoclave testing and temperature cycling in air/water vapor environment. A platinum-based high-temperature metallization scheme deposited on oxidized Si substrates was used as a test vehicle. The a-SiO_x/a-SiC:H stack showed the best performance when compared to standard passivation materials as amorphous silicon oxide or silicon nitride coatings.     

金刚石/碳化硅复合梯度膜制备研究

采用微波等离子化学气相沉积(MW-PCVD)制备金刚石/碳化硅复合梯度膜.工作气体为H₂,CH₄和Si[CH₃]₄(四甲基硅烷,TMS),其中H₂∶CH₄=100∶0.6,Si[CH₃]₄为0％-O.05％,沉积压力为3300Pa,基体温度为700℃,微波功率为700W.基体为单晶硅,在沉积前用纳米金刚石颗粒处理.沉积后的样品经扫描电子显微镜(SEM),电子探针显微分析(EPMA),X射线能量损失分析(EDX)表明:沉积膜中的碳化硅含量是随Si[CH₃]₄流量的变化而改变.通过改变Si[CH₃]₄的流量可以制备金刚石/碳化硅复合梯度膜,且梯度膜中金刚石与复合膜过渡自然平滑.     

Microcrystalline silicon carbide thin films grown by HWCVD at different filament temperatures and their application in n-i-p microcrystalline silicon solar cells

To optimize the performance of microcrystalline silicon carbide (µc-SiC:H) window layers in n-i-p type microcrystalline silicon (µc-Si:H) solar cells, the influence of the rhenium filament temperature in the hot wire chemical vapor deposition process on the properties of µc-SiC:H films and corresponding solar cells were studied. The filament temperature T_F has a strong effect on the structure and optical properties of µc-SiC:H films. Using these µc-SiC:H films prepared in the range of T_F = 1800-2000 °C as window layers in n-side illuminated µc-Si:H solar cells, cell efficiencies of above 8.0% were achieved with 1 µm thick µc-Si:H absorber layer and Ag back reflector.