大尺寸化学Ni源金属诱导晶化多晶硅的研究

用无电电镀的化学方法，在VHF-PECVD沉积获得的非晶硅薄膜表面形成镍诱导源，在550℃下退火若干小时，可以诱导产生微米量级的多晶硅晶粒.用此法形成的镍源可以均匀地分布在非晶硅薄膜的表面.非晶硅薄膜上形成晶核的数量取决于镍溶液的浓度、pH值和无电电镀的时间等参量.当成核密度比较低时可以观察到径向晶化现象.用VHF-PECVD非晶硅薄膜作为晶化前驱物，晶化后多晶硅的最大晶粒尺寸可达到90μm.用此多晶硅试制的TFT，获得了良好的器件特性. 关键词： 金属诱导晶化 化学源 多晶硅 薄膜晶体管     

用镍硅氧化物源横向诱导晶化的多晶硅薄膜

采用磁控溅射法,以镍硅合金为靶,制备了一种适用于金属诱导横向晶化的氧化物镍源——自缓释镍源.该镍源在内部构成和晶化现象上都不同于纯金属镍源.采用该镍源制备低温多晶硅材料,晶化速率不明显依赖于镍源薄膜的厚度,且晶化多晶硅膜内的残余镍量亦可有效降低,可为薄膜晶体管提供宽的工艺窗口.本文对用纯金属镍源所得多晶硅薄膜的晶化率、表面粗糙度、电学特性等与溅射条件的关系进行了研究,并对相应结果进行了讨论.     

用镍硅氧化物源横向诱导晶化的多晶硅薄膜

采用磁控溅射法,以镍硅合金为靶,制备了一种适用于金属诱导横向晶化的氧化物镍源——自缓释镍源.该镍源在内部构成和晶化现象上都不同于纯金属镍源.采用该镍源制备低温多晶硅材料,晶化速率不明显依赖于镍源薄膜的厚度,且晶化多晶硅膜内的残余镍量亦可有效降低,可为薄膜晶体管提供宽的工艺窗口.本文对用纯金属镍源所得多晶硅薄膜的晶化率、表面粗糙度、电学特性等与溅射条件的关系进行了研究,并对相应结果进行了讨论. 关键词： 自缓释 金属诱导横向晶化 多晶硅薄膜 低温制备与退火     

单畴Ni球观测及NicoreNiOshell的铁磁/反铁磁耦合研究

 使用微波辅助聚合方法制备了单分散单畴Ni纳米球，由MFM发现，尺度分布在100～180 nm的Ni球的一个相关特征是条型磁畴结构。用XRD、TEM、XPS以及EDAX测量了由Ni球进一步制备的Ni_coreNiO_shell高度球型纳米结构。用VSM 和SQUID进一步讨论了其铁磁/反铁磁界面耦合效应，估算了交换耦合场与粒子尺寸的关系。     

Cross-section measurement for Ni(n,x)58(m+g)Co,Ni(n,x)60mCo,Ni(n,x)61Co and Ni(n,x)62mCo reactions induced by neutrons around 14MeV

The cross sections of Ni(n,x)58(m+g)CO,Ni(n,x)80mCo,Ni(n,x)61Co and Ni(n,x)62mCo reactions induced by neutrons around [14]MeV were measured in this work and calculated by a previously developed formula in this work.The neutron flux was determined using the monitor reaction 27Al(n,α)24Na and the neutron energies were measured with the method of cross-section ratios for 89Zr(n,2n)89Zr to 93Nb(n,2n)92mNbreactions.     

Cross-section measurement for Ni（n,x）^58（m＋g）Co, Ni（n, x）^60mCo, Ni（n,x）^61Co and Ni（n,x）^62mCo reactions induced by neutrons around 14 MeV

The cross sections of Ni(n,x)~(58(m g))Co,Ni(n,x)~(60m)Co,Ni(n,x)~(61)Co and Ni(n,x)~(62m)Co reactions induced by neutrons around 14 MeV were measured in this work and calculated by a previously developed formula in this work.The neutron flux was determined using the monitor reaction ~(27)Al(n,α)~(24)Na and the neutron energies were measured with the method of cross-section ratios for ~(90)Zr(n,2n)~(89)Zr to ~(93)Nb(n,2n)~(92m)Nb reactions.     

Electron spectroscopies for simultaneous chemical and electrical analysis

Electrons are used as spectroscopic probes to determine elemental composition and chemistry, and are also useful as probes of the electrical properties of devices and materials. In this paper, four examples with incident and emitted electrons were used to evaluate the electrical and chemical properties of samples. These examples were the electrical conductivity of an Ag-epoxy composite, the electric field in an avalanche photodiode near breakdown, the mechanism of conductivity of semi-insulating polycrystalline films, and the charge at an oxide/semiconductor interface for high-k applications. This kind of work is very much in the spirit of the work done by Prof. Sefik Suzer.     

常压化学气相沉积法在Ag/Si(111)模板上生长ZnO薄膜及其性能研究

在Si衬底上利用磁控溅射的方法沉积1.5 nm厚度的Ag膜用以阻挡Si衬底被氧化。采用常压金属有机化学气相沉积法(MOVCD),在Ag/Si(111)衬底上成功地生长出马赛克结构的ZnO薄膜。用光学显微镜观察表面形貌,结果显示有带晶向特征的微裂纹,裂纹密度为100 cm-1。依据X射线晶体衍射的结果,薄膜结晶质量良好,呈C轴高度择优取向。用双晶X射线衍射得到(002)面的ω扫描半峰宽为1.37°。温度10 K时光致发光谱(PL)观察到自由激子、束缚激子发射及它们的声子伴线。结果表明,金属有机化学气相沉积法方法在Si(111)衬底上制备ZnO薄膜时,Ag是一种有效的缓冲层。     

Miscibility and Isothermal Crystallization Behavior of Poly (Butylene Succinate-co-Adipate) (PBSA)/Poly (Trimethylene Carbonate) (PTMC) Blends

Poly(butylene succinate-co-adipate) (PBSA)/poly (trimethylene carbonate) (PTMC) blend samples with different weight ratios were prepared by solution blending. The morphologies after isothermal crystallization and in the melt were observed by optical microscopy (OM). Differential scanning calorimetry (DSC) was used to characterize the isothermal crystallization kinetics and melting behaviors. According to the OM image before and after melting, it was found that the blends formed heterogenous morphologies. When the PTMC content was low (20%), PBSA formed the continuous phase, while when the PTMC contents was high (40%), PBSA formed the dispersed phase. The glass transition temperatures (T_g) of the blends were determined by DSC and the differences of the T_g values were smaller than the difference between those of pure PBSA and PTMC. In addition, the equilibrium melting points were depressed in the blends. According to these results, the PBSA/PTMC blends were determined as being partially miscible blends. The crystallization kinetics was investigated according to the Avrami equation. It was found that the incorporation of PTMC did not change the crystallization mechanism of PBSA. However, the crystallization rate decreased with the increase of PTMC contents. The change of crystallization kinetics is related with the existences of amorphous PTMC, the partial miscibility between PLLA and PTMC, and the changes of phase structures.     

Synthesis of Poly(butylene terephthalate)/Attapulgite Nanocomposites by In-Situ Polymerization and Its Crystallization Behavior

Poly(butylene terephthalate) (PBT)/attapulgite (AT) nanocomposites were prepared via in-situ polymerization without pre-modification of AT. By this method, PBT chains were successfully grafted onto the surface of AT, which was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Scanning electron microscope examination indicated the uniform dispersion of AT nanoparticles in PBT matrix. The crystallization behavior of PBT/AT nanocomposites was investigated by X-ray diffraction patterns, differential scanning calorimetry, and step-scan differential scanning calorimetry. The non-isothermal crystallization processes were analyzed with the Avrami, Ozawa, and Mo methods. Crystallization activation energies of the samples were also determined by the Kissinger method. The results indicated that AT could act as a heterogeneous nucleating agent in PBT crystallization and lead to an acceleration of crystallization, while AT also acted as a physical hindrance to retard the transport of polymer chains to the growing crystals.     

Controlling surface states and photoluminescence of porous silicon by low-energy-ion irradiation

Porous silicon (PS) was irradiated by three kinds of low-energy ions with different chemical activity, namely argon ions, nitrogen ions and oxygen ions. The chemical activity of ions has significant effect on the surface states and photoluminescence (PL) properties of PS, The photoluminescence quenching after argon ions and nitrogen ions irradiation is ascribed to the broken Si-Si bonds, while the PL recovery is attributed to the oxidation of Si-H back bonds. Oxygen ions irradiation leads to the formation of a SiO_x layer with oxygen defects and PS shows different PL evolution than PS irradiated by argon ions and nitrogen ions.     

Structural and optical properties study of nanocrystalline Si (nc-Si) thin films deposited on porous aluminum by plasma enhanced chemical vapor deposition

In this paper we report detail investigation and correlation between micro-structural and optical properties of nanocrystalline silicon (nc-Si) deposited by plasma enhancement chemical vapor deposition (PECVD) on porous aluminum structure. The influence of the microstructure of the nc-Si thin films on their optical properties was investigated through an extensive characterization. The effect of anodisation currents on the microstructure of aluminum surface layer and nc-Si films was systematically studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). The optical constants (n and k as a function of wavelength) of the films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The silicon layer (SL) was modeled as a mixture of void, crystalline silicon and aluminum using the Bruggeman approximation. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties. A very bright photoluminescence (PL) was obtained and find to depend on anodisation current.     

线性、径向和环向偏振飞秒激光诱导非晶合金周期性表面结构

研究在复杂偏振条件下,飞秒激光诱导非晶合金Zr44Ti11 Cu10Ni10Be25(at％)表面周期性结构的形成机理.实验采用波长800 nm、脉宽120 fs的超短脉冲激光,分别在线性、径向、环向偏振条件下,诱导非晶合金表面生成复杂的周期性表面结构.表面结构由周期为652～723 nm的低频条纹和周期为1 304～1 765 nm的微型条纹组成.通过有限差分时域法仿真分析,发现微型条纹由粗糙表面引起的定向调制的表面散射电磁波与入射激光干涉形成.仿真结果与实验结果一致,验证了微型条纹形成机理的有效性.     

Flat-topped Mathieu-Gauss beam and its transformation by paraxial optical systems

In order to avoid the severe axial intensity oscillations which appear when an ideal Mathieu beam is truncated, we propose to modulate it by a flattened multi-Gaussian envelope. The obtained beam, which is referred as flattened Mathieu-Gauss (FTMG) beam, can be expanded into a finite series of Mathieu-Gauss beams with various waists. The propagation study of this beam reveals that the axial intensity is unchanged within a certain propagation distance as for super-Gaussian-Bessel beams or Gori’s flattened Bessel beams. By using Collins formula, we derive closed-form expressions of FTMG beam propagating through a paraxial axisymmetric ABCD optical system. Some numerical calculations and discussions are also given.     

Study of the magnetism and the magnetic anisotropy of Fe layers in Ni/Fe/Ni(1 1 1) by Mössbauer spectroscopy

The hyperfine field and the magnetic anisotropy of a Fe layer as a function of thickness have been investigated in several Ni/⁵⁷Fe_x/Ni(1 1 1) trilayers with relatively thick Ni layers by Mössbauer spectroscopy. For Fe layers with thickness below 16 Å, the Mössbauer spectra show always the presence of two ferromagnetic phases with high-spin state. In the range between 6 and 8 Å, also a ferromagnetic phase with low-spin state and a paramagnetic phase have been found. The evolution of the mean hyperfine field of the ⁵⁷Fe nuclei is used to study the Fe growth. A structural FCCBCC phase transition is found to begin with an iron thickness of 8 Å. The easy direction of the magnetization is found out-of-plane for Fe interlayer with FCC structure, and perfectly in plane for Fe interlayer with BCC structure.     

金属有机化学气相沉积生长Zn1-xMnxSe薄膜的发光和磁光性质

利用金属有机化学气相沉积(MOCVD)方法在GaAs衬底上生长了不同组分的Zn_1-xMn_xSe薄膜。X射线衍射和X射线摇摆曲线证明样品具有较好的结晶质量。在低温、强磁场下对样品的发光进行了研究,在带边附近观察到两个发光峰的相对强度随着磁场增强发生了变化。通过变温光谱探讨了这两个发光峰的来源,并被分别归因于自由激子跃迁和与Mn有关的束缚态激子跃迁。同时随着磁场的增强,ZnMnSe带隙发光红移是由于类S带和类P带电子与Mn离子的3d⁵电子的自旋交换作用。     

Static and Dynamic Quenching of Tryptophan Fluorescence in Various Proteins by a Chromium (III) Complex

The interaction of a chromium (III) complex, (R,R)-N,N′-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diaminochromium (III), with human serum albumin, bovine serum albumin, lysozyme, and free tryptophan was studied using steady-state fluorescence spectroscopy. Dynamic and static quenching constants were calculated using Stern-Volmer kinetics. The complex bound more tightly to the serum albumins than to lysozyme or free tryptophan, but only one binding site was determined in all systems. The interaction was also determined to be thermodynamically favorable, and the binding constants were on the order of 10³–10⁶. The fluorescence quenching was static in nature with Forster distances in the 1.8–2.0 nm range.     

ICP法测定超临界水氧化设备腐蚀液中铜、铬、铝、镍、钛

采用光谱法研究了超临界水氧化设备腐蚀液中Cu,Cr,Al,Ni和Ti元素的含量,分析判断不锈钢设备腐蚀状况及其因素。结果表明,超临界设备不锈钢材料主要成分元素Cr在超临界水中有不同程度的溶解,并且溶解程度随温度和压力升高而增大。     

LP-MOCVD异质外延ZnO薄膜中的应力及对缺陷的影响

利用低压金属有机化学气相淀积(LP-MOCVD)在Si基片上外延生长ZnO薄膜，制备了两类样品 ：一类是在Si上直接外延ZnO，另一类是在Si上通过SiC过渡层来外延ZnO.根据两类样品的拉 曼光谱、x射线衍射、原子力显微图和光致发光的结果，表明ZnO外延薄膜中的张应力对薄膜 的结晶状况有着重要的影响，使用SiC过渡层能够有效缓解ZnO薄膜中的张应力，减小缺陷浓 度，提高ZnO外延层的质量；然后根据缺陷的形成机制进一步提出，对于ZnO/Si，其中较大 的张应力导致了高浓度的非辐射复合缺陷的形成，使得样品的紫外和绿峰的发射强度均大大 降低；对于ZnO/SiC/Si，其中较小的张应力导致ZnO薄膜中主要形成氧替位缺陷O_{Zn，从而使发光中的绿峰增强. 关键词： ZnO薄膜 应力 缺陷 拉曼光谱}