In-situ study of stress evolution during solid state reaction of Pd with Si(001) using synchrotron radiation

Using X-ray diffraction experiments and curvature measurements, in-situ real-time measurements of stress are performed during solid state reaction of a palladium thin film with Si(001). From X-ray diffraction measurements and using the sin²ψ method, we found out that the stress in the metal and in the silicide is compressive. This stress decreases all along the solid-state reaction for the silicide. We then compared our results with the qualitative model proposed by Zhang and d’Heurle. This model suggests the development of a high compressive stress (−2.4 GPa) in the silicide.     

n型SiC的Ni基欧姆接触中C空位作用的实验证明

通过在Si面p型4H-SiC外延层上使用P+离子注入来形成n阱.Ti和Ni依次淀积在有源区的表面,金属化退火后的XRD分析结果表明Ni2Si是主要的合金相.XEDS的结果表明在Ni2Si/SiC界面处存在一层无定型C.去除Ni2Si合金相与无定型C之后重新淀积金属,不经退火即可形成欧姆接触.同时,注入层的方块电阻Rsh从975下降到438Ω/□.结果表明,合金化退火过程中形成了起施主作用的C空位(VC).C空位提高了有效载流子浓度并对最终形成欧姆接触起到了重要作用.     

Explosive crystallization of rf-sputtered amorphous CdTe films

Explosive crystallization of about 2-μm thick amorphous CdTe films prepared by rf-sputtering in an Ar-N₂ ambient has been observed. The transformation can be initiated with or without external thermal or mechanical impulses depending on the oxygen content of the films. The crystallization is accompanied by a light flash. X-ray diffraction, Auger analysis, and resistivity measurements were made on these films to arrive at a qualitative model to explain the observations.     

钛酸钡粉体四方相的XRD定量分析

通过对标准试样进行X-射线衍射(XRD)测试，根据衍射峰的积分强度、衍射角及晶面间距等数据对超细钛酸钡粉体四方相的含量进行了定量分析，该文的研究发现衍射角比衍射峰强度的数据有相对的稳定性，根据两峰衍射角之差来分析四方相含量较准确，从而为水热法制备四方相钛酸钡粉体的含量表征提供了一种简单的分析手段。     

Determination of absolute thickness and mean free path of thin foil specimen by zeta-factor method

The zeta-factor method is applied to the thickness determination of thin amorphous specimens where the convergent-beam electron diffraction method is not applicable. Characteristic X-ray intensities are first measured using standard specimens in order to determine zeta-factors. These zeta-factors are then used to determine local thicknesses of an amorphous Si and an amorphous Al alloy. Electron energy-loss spectroscopy (EELS) spectra are acquired at the same positions as for the X-ray measurements. Thus, using the thicknesses measured from the zeta-factor method, the electron mean-free path is determined through the EELS log-ratio method. The mean free path is measured as a function of the collection semi-angle, beta, and specimen thickness, and it is also compared with theoretical values. Furthermore, the mean free path of amorphous Si is compared with that of the crystalline Si.     

激光上釉非晶层的组织结构研究

本文研究在Fe-Ni-Cr-Si-B合金和铸态共晶等试样上采用10kw高功率连续CO_2激光上釉方法获得的激光非晶薄层。观察了激光上釉非晶化熔区的组织特征,分析了组织转变的过程。分析了激光上釉熔区表层的白亮组织,确认了非晶态的存在,并用显微硬度计检测了激光上釉熔区的硬度分布。     

Real structure of partially ordered crystals

Partial order in crystals is a frequently observed phenomenon in minerals and synthetic materials. The partially ordered structures are characterized by low-dimensional order of the real structure. In the case of 1D structures, the ordered units can be described as rods; 2D structures contain ordered layers. The disorder of the real structures is indicated by prominent diffuse scattering in the diffraction patterns of single crystals. No simple method for the quantitative analysis of the diffuse scattering exists, therefore the determination of essential characteristics of the structures is complicated. However, the determination can be facilitated using a combination of different methods, including electron microscopy, computation and X-ray diffraction.     

退火过程对c轴择优取向的ZnO薄膜的光学性质的影响

利用溶胶凝胶法在石英衬底上采用旋涂法制备出ZnO薄膜,通过X射线衍射仪发现不同的退火温度对ZnO薄膜的择优取向有很大影响;通过紫外可见分光光度计和室温发光谱可以看出,制备的薄膜有很好的光学透过性和很强的紫外发光特性,而不同的退火温度对其光学性质有很大的影响。实验发现采用此种方法在650℃左右退火是一个合适的退火温度,结构特性和光学性质都相对较好;采用热分析方法可知ZnO将在375℃左右从非晶转向结晶状态,因而在常规ZnO薄膜制备方法中增加一步500oC的热处理将有助于提高ZnO薄膜的结晶质量。     

An Investigation of Diffusion Barrier Characteristics of an Electroless Co(W,P) Layer to Lead-Free SnBi Solder

Diffusion barrier characteristics for eutectic SnBi solder/electroless Co(W,P) couples were investigated via liquid-state aging at 250°C and solid-state aging at 120°C. At the couple interface, CoSn₃ intermetallic compound (IMC) spallation was observed for the SnBi/amorphous Co(W,P) couple subjected to liquid-state aging. In contrast, no spallation of IMCs was observed for the SnBi/amorphous Co(W,P) couples subjected to solid-state aging. For the SnBi/polycrystalline Co(W,P) couple, a thick IMC layer was observed adjacent to a tungsten-enriched amorphous interfacial layer regardless of aging conditions. IMC formation in all samples indicated that Co(W,P) is essentially a sacrificial barrier to SnBi solder. However, amorphous Co(W,P) might also exhibit stuffed-type barrier behavior due to its relatively high phosphorus (P) content. Analytical results indicated that the P content in Co(W,P) is a crucial factor affecting the structural evolution at the SnBi/electroless Co(W,P) interface.     

Comparing the growth of a molecular semiconductor on amorphous and semi-crystalline polycarbonate substrates

Polymeric substrates are of importance in plastic electronics. However, polymeric surfaces can exhibit different morphologies depending on whether they are amorphous or semi-crystalline. This work focuses on the impact of the surface structure of bisphenol A polycarbonate substrates on the nucleation and growth of a p-type semi-conductor, namely zinc phthalocyanine (ZnPc). ZnPc films were deposited under high vacuum at different substrate temperatures on oriented semi-crystalline as well as amorphous substrates of PC. The oriented substrates of PC were prepared by a method combining mechanical rubbing and solvent induced crystallization: the substrates show a periodic and regular alternation of oriented crystalline lamellae. Grazing incidence X-ray diffraction shows that the crystalline lamellae of PC have a preferential (a, c) contact plane. Moreover, the substrates show a bilayer structure made of a 60 nm-thick semi-crystalline overlayer atop an amorphous underlayer. UV–vis spectroscopy shows that the polymorphism of the ZnPc films is not modified by the surface structure of the PC substrate (amorphous versus semi-crystalline). However, the statistical analysis of domain size and density versus substrate temperature T_s evidences different apparent activation energies of the growth mechanism. High Resolution Transmission Electron Microscopy suggests that twinning along a (2 ?1 0) plane accounts for the bifurcations of the in-plane b-axis direction of the ZnPc nanocrystals. On oriented substrates of PC, such bifurcations are partly suppressed by the nanocorrugation of the surface, resulting in larger apparent domain sizes and unidirectional in-plane orientation.     

Determination of the degree of ordering of materials’ structure by calculating the information-correlation characteristics

A new method for the analysis of self-organization processes in solid-state materials by calculating the information-correlation characteristics of a surface (in particular, by calculating the average mutual information) is described. Criteria for determining the degree of ordering of a surface structure are suggested; these criteria have been tested for experimental semiconductor structures of single-, poly-crystalline, and amorphous silicon. The dependences of the information characteristics for films of disordered semiconductors on the technological conditions of their fabrication are established.     

溶胶-凝胶法制备高c轴取向纳米V_2O_5薄膜

采用溶胶-凝胶法,以二乙酰丙酮氧钒(VO(C5H7O2)2)为前驱物,通过提拉方式,在预镀非晶SiO2薄膜的硼硅玻璃上制备多晶纳米五氧化二钒(V2O5)薄膜。通过X射线衍射、傅里叶变换红外吸收光谱、紫外-可见-近红外光谱等表征手段对不同热处理条件下的样品进行了结构和光学性能分析。结果表明,热处理温度在350～550℃,无论是在空气中还是在氧分压为0.1Pa的氮气中,均能得到高c轴取向生长的纳米V2O5薄膜,结晶性能良好,晶粒尺寸分布在21～45nm,样品在810cm-1和1026cm-1附近存在对应于5价钒氧化物的红外吸收峰,在500nm出现强烈的带间吸收。与现有的溶胶-凝胶法相比,本实验选用的VO(C5H7O2)2是制备高c轴生长、结晶性好的纳米V2O5薄膜的理想前驱物。     

流量对高速沉积的微晶硅电池性能的影响

采用超高频等离子体增强化学气相沉积(VHF-PECVD)技术研究微晶硅(μc-Si)薄膜的高速沉积过程发现:分别采用100和500 sccm流量制备本征μc-Si材料,将其应用在μc-Si电池i层,电池的电流-电压(I-V)特性有明显的差异.通过微区Raman、原子力显微镜(AFM)和X射线衍射(XRD)测试发现:尽管μc-Si薄膜的晶化率相似,但是小流量情况下制备的薄膜具有较厚的非晶孵化层,晶粒尺寸不一;大流量下制备的材料沿生长方向的纵向均匀性相对较好,晶粒尺寸较小、分布均匀,而且具有〈220〉晶相峰强度高于〈111〉和〈311〉晶相峰强度的特点.因此得出:在高压高速沉积μc-Si薄膜过程中,反应气体流量对μc-Si的纵向结构有很大影响,选择适合的反应气流量能够调节适宜的气体滞留时间,从而减小薄膜的纵向不均匀性.     

Inter-triplet spin–spin interaction effects on inter-conversion between different spin states in intermediate triplet–triplet pairs towards singlet fission

This article reports the experimental studies on the effects of inter-triplet spin interaction on singlet fission by using magnetic field effects of photoluminescence (MFE_PL) based on tetracene. The MFE_PL are compared for three different morphological states based on polycrystalline solid powder, amorphous solid film, and liquid solution. It is observed that the polycrystalline solid powder gives stronger MFE_PL than that of amorphous solid film, while the liquid solution exhibits no detectable MFE_PL. In essence, the MFE_PL are determined by the inter-conversion between different spin states initiated by inter-triplet spin interaction through spin mixing in intermediate triplet–triplet pairs towards the singlet fission. The different MFE_PL amplitudes suggest that the polycrystalline solid powder possesses an enhanced inter-triplet spin interaction in intermediate triplet–triplet pairs as compared to amorphous solid film. As a result, the enhanced inter-triplet spin interaction can cause a larger inter-conversion between different spin states in intermediate triplet–triplet pairs and consequently increases the singlet fission within polycrystalline structures. The absorption spectral characteristics and X-ray diffraction data confirm that the polycrystalline solid powder can indeed exhibits stronger intermolecular electronic interaction relative to amorphous solid film. Here, the stronger intermolecular electronic interaction provides an evidence for the enhanced inter-triplet spin interaction occurring within polycrystalline structures in the solid powder. Our experimental results indicate that increasing the inter-triplet spin interaction can boost the inter-conversion between different spin states in intermediate triplet–triplet pairs and consequently facilitates the singlet fission.     

Microstructure and texture of free-standing Cu-line patterns

Free-standing discontinuous Cu-line patterns varying in line widths and interline distances in the range of a few micrometers were manufactured by combining photolithography and electrochemical deposition. Two principally different seed layers, polycrystalline Au and X-ray amorphous Ni-P, were applied prior to electrodeposition of the Cu lines as well as continuous Cu films, which were deposited as reference. The effect of the seed layer and the influence of the pattern design on surface topography and morphology of the deposits were studied by means of light optical and scanning electron microscopy (SEM). The growth behavior is related to the developing crystallographic texture of Cu-line patterns and continuous films, as determined from calculated orientation distribution functions (ODFs) on the basis of X-ray diffraction (XRD) pole figure measurements. While strong crystallographic textures of Cu lines on polycrystalline Au were observed with pattern-dependent differences to continuous films, almost no preferred grain orientations develop both for Cu lines and corresponding continuous films deposited on amorphous Ni-P.     

Reverse Monte Carlo analysis of extended energy-loss fine structure for disordered structures of tetrahedrally coordinated materials: its applicability

Capabilities of the reverse Monte Carlo method for characterizing the short-range structural correlations of solids were examined in the analysis of extended energy-loss fine structure (EXELFS). Since this method gives a three-dimensional atomic configuration consistent with the experimental EXELFS spectra, one can extract the statistical distributions of bond lengths, coordination numbers and bond angles of atom species of interest, which have been hard to achieve by conventional EXELFS analysis. The method was applied for the determination of amorphous Si structures and the damaged structure of an electron-irradiated SiC crystal. Advantages and disadvantages of the present method over the precise diffraction intensity measurement are discussed.     

直流磁控溅射制备非晶硅薄膜的研究

非晶硅薄膜（a-Si）是目前重要的光敏材料,在很多领域得到广泛应用。直流磁控溅射具有工艺简单．沉积温度低等优点,是制备薄膜的一种重要技术。采用直流磁控溅射工艺在玻璃基板上沉积薄膜,并对样品进行了退火处理。研究了沉积速率与溅射功率的关系。结果表明薄膜的沉积速率与溅射功率近似有线性关系。利用X射线衍射（XRD）对薄膜进行了分析鉴定,结果表明溅射的薄膜是非晶硅薄膜。利用扫描电子显微镜（SEM）对非晶硅薄膜的表面形貌进行了观察和分析,与X射线衍射测试的结果一致。所以．利用直流磁控溅射工艺能在常温下能快速制备出良好的非晶硅薄膜。     

无定型SiO2对纳米ZnO缺陷发光的辅助增强效应研究

利用正硅酸乙酯水解后的无定型SiO2网络结构,合成了不同尺度的纳米ZnO。X射线衍射(XRD)谱显示,当正硅酸乙酯的量从0ml增加到5ml,ZnO的粒径从14.6nm减小到1.9nm;光致发光(PL)光谱显示,发射峰位从560nm蓝移到510nm,发射强度明显增强。利用紫外-可见(UV-VIS)吸收光谱、PL光谱以及能级结构分析,我们认为,纳米ZnO随尺度下降所产生的发光增强来源于无定形SiO2所抑制的ZnO表面非辐射跃迁过程以及二者之间的再吸收过程;此外,纳米ZnO尺度的下降,使得其表面的光生电子和晶格内部的O空位(Vo)之间的距离减小,提高了辐射跃迁的几率也是获得高荧光效率的可能原因。     

利用热退火法从非晶硅薄膜中生长纳米硅粒

报道了一种从氢化非晶硅薄膜中生长纳米硅粒的方法.氢化非晶硅薄膜经过不同条件的热退火处理后,用拉曼散射和X射线衍射技术对样品进行了分析.实验结果表明:在快速升温条件下所形成的nc-Si在薄膜中的分布是随机均匀的,直径在1.6～15 nm范围内,硅粒大小随退火过程中升温快慢而变化.     

Effect of strontium nitride on the properties of Sr_2Si_5N_8:Eu~(2+) red phosphor

The nitride phosphor Sr_2Si_5N_8:Eu~(2+) was synthesized by the high temperature solid-state method.The properties of Sr_2Si_5N_8:Eu~(2+) were discussed by X-ray diffraction(XRD) scanning electron microscope(SEM) and spectra analysis.The XRD pattern shows that the single phase produces when strontium nitride is a bit excessive. The SEM photo implies that the excessive strontium nitride works as a flux in the reaction system.The position of emission peak is also located at about 612 nm as strontium nitrid...