Cu—Ge 非晶薄膜的形成与晶化研究

采用液氮冷却基片的气相沉积法,制备了 Cu-Ge 非晶薄膜。电阻测量及 TEM 形貌、电子衍射等分析表明,非晶态合金的形成能力及稳定性与成分密切相关。对 Cu_(100-x)Ge_x 合金膜,在x<25成分区,形成的非晶态稳定性差,晶化初期出现 fcc 结构的亚稳晶相;在 x>25成分区,有较高稳定性的非晶相形成,晶化后形成 Cu_3Ge 相。用合金化化学键效应观点解释了非晶态的形成、结构及结构转变行为。     

非晶态 Li~+ 导体分相和晶化过程的扫描电镜观察

对非晶态 Li~+导体 B_2O_3—0.7Li_2O—0.7LiCl—0.1Al_2O_3在300℃温度下分相和晶化过程进行了扫描电镜(SEM)观察。结果表明;在等温处理的开始阶段,样品内首先发生分相,从母相中分离出均匀分布的新的非晶相粒子,随后长大和聚集;然后,新非晶相发生晶化长成晶粒,其成分为 Li_4B_7O_(12)Cl;最后,背景的非晶相中析出另一种晶粒,成分为 LiBO_2,并有较大的生长速度。     

Zr对非晶Co-Si薄膜晶化和相变的影响

利用X射线衍射分析技术结合差示扫描量热仪,研究了Zr在Co-Si合金非晶薄膜晶化和相变过程中的作用.结果表明:溅射态非晶Co-Si薄膜和Co-Si-Zr薄膜在加热到950℃的过程中,均主要析出Co-Si和Co-Si2两种晶化相;Zr的加入增大了晶化激活能,抑制了晶化相的形核和长大,使薄膜能够在更高的温度范围保持稳定,但在高温800℃以上加热时,却使晶化相Co-Si向Co-Si2的转变加快.     

离子束混合制备非晶Sm-Fe-Zr合金薄膜

采用离子束混合技术制备非晶Sm—Fe－Zr合金薄膜，在Sin的含量为x＝400，300，200m／g的Sm—Fe多层薄膜中，注入能量为60KeV，剂量为1×1017ion／cm2的Zr＋，研究非晶形成条件及合金薄膜的磁性能．实验发现：三种成分配比的样品在Zr＋注入后磁性能皆发生明显的变化．X＝400mg／g样品没有形成非晶，其主相为SmFe5；x＝300，200mg／g样品形成非晶，且x＝200mg／g样品晶化后形成一个面心结构未知相和α—Fe相     

近等原子比TiNi合金薄膜的组织及相变动态观察

采用磁控溅射法制备TiNi非晶薄膜.通过X射线衍射(XRD)、透射电子显微镜(TEM)等方法研究了TiNi合金薄膜的组织形貌、电子衍射花样,并对其相变过程进行了动态观察.结果表明:态薄膜为非晶态,对其在515℃进行1 h的晶化处理后,薄膜中析出了TiNi3相;晶化处理后的TiNi合金薄膜加热到100℃时,薄膜中R相和马氏体相以切变方式完全转变为奥氏体;当冷却至室温时,是以R相、马氏体相以及少量的奥氏体相存在.其加热过程中的相变顺序为:马氏体相→R相→奥氏体相.冷却过程中的相变顺序为:奥氏体相→R相→马氏体相.     

一种富钛NiTi薄膜的晶化动力学

本实验采用直流磁控溅射法制备了一种非晶的富TiNiTi薄膜，其成分为Ni46.34%（原子分数），Ti53.66％（原子分数）。采用变温方法研究了这种非晶薄膜的晶化动力学。测得非晶薄膜晶化的激活能为271kJ/mol，平均Avrami指数为1．17。采用以上获得的动力学参数计算了薄膜在773K的等温晶化动力学曲线。计算结果与实验结果吻合较好。在薄膜的晶化过程中伴随着Ti2Ni的析出。     

二元不互溶Cu-Ta体系非晶相的形成

利用X射线衍射(XRD)、高分辨透射电子显微术(HRTEM)和X射线能谱(EDS)研究了共溅射Cu-Ta薄膜中非晶相的形成.结果表明,共溅射Cu-Ta薄膜为非晶相,但是其中存在着纳米尺度的Cu晶粒和富Cu的非晶纳米颗粒,即存在纳米尺度的相分离.正的混合热是导致Cu-Ta二元不互溶体系非晶态薄膜相分离的本质原因.     

非晶态固体在压力下的晶化

综述了压力对非晶态合金的晶化行为的影响。首先介绍压力作用对不同类型晶化过程的作用，主要是晶化温度的变化，然后通过体积变化、原子扩散、界面和塑性变形几个方面分析压力如何影响非晶态固体晶化过程的。多数非晶合金体系表现出晶化温度随压力升高，热稳定性增加，说明原子扩散仍然是主要的影响因素。此外，少数非晶合金体系则需要考虑新生晶体／非晶界面的作用，在一定条件下，晶化温度反而随压力升高而下降。塑性变形也可以降低非晶的热稳定性。     

互不固溶系统的固态反应非晶化

利用选区电子衍射和Ｘ射线衍射研究了互不固溶系统Ｃｕ－Ｔａ和Ｃｕ－Ｎｂ纳米多层膜的固态反应非晶化的可能性，结果表明：当单层厚度减小到一定程度，成分为２５～３０％Ｃｕ的多层膜可以通过退火实现固态反应非晶化，从而获得具有正混合热系统的非晶薄膜，在Ｃｕ－Ｔａ系统中还获得了厚０．８μｍ的非晶态薄膜，互不固溶系统多层膜固态反应非晶化的热力学驱动力主要源于多层膜界面自由能。     

沉积温度对ZrO2薄膜结构及表面形貌的影响

采用反应磁控溅射方法,在室温～550℃的沉积温度下,在Si(100)和玻璃基片上沉积了厚度在纳米量级的ZrO2薄膜.通过高分辨电子显微镜、原子力显微镜和透射光谱分析,研究了沉积温度对ZrO2薄膜的相结构、表面形貌和折射率的影响.研究结果表明沉积温度低于250℃时,ZrO2薄膜的结构完全呈非晶态,但250℃沉积的薄膜有比较高的致密度;随着沉积温度的升高,薄膜出现了明显的结晶现象,主要为单斜ZrO2相;沉积温度为450℃时,ZrO2薄膜晶化不完全,在晶粒堆砌处有非晶ZrO2相存在;沉积温度为550℃时,ZrO2薄膜完全晶化,在晶粒堆砌处有四方ZrO2相存在.此外,根据薄膜相结构和表面形貌的研究结果,探讨了沉积温度对薄膜生长行为的影响及其物理机制.     

Effect of zirconium addition on formation of CoSi<Subscript>2</Subscript> thin films

CoSi₂ thin films were prepared by annealing the amorphous Co-Si thin films. Zr was added into the amorphous thin film in order to investigate its effect on formation of CoSi₂ thin film. It was found that Zr increased the crystallization nucleation barrier and accelerated the complete transformation of CoSi to CoSi₂.     

Cobalt silicide nanocables grown on Co films: synthesis and physical properties

Single-crystalline cobalt silicide/SiO(x) nanocables have been grown on Co thin films on an SiO(2) layer by a self-catalysis process via vapor-liquid-solid mechanism. The nanocables consist of a core of CoSi nanowires and a silicon oxide shell with a length of several tens of micrometers. In the confined space in the oxide shell, the CoSi phase is stable and free from agglomeration in samples annealed in air ambient at 900?°C for 1?h. The nanocable structure came to a clear conclusion that the thermal stability of the silicide nanowires can be resolved by the shell encapsulation. Cobalt silicide nanowires were obtained from the nanocable structure. The electrical properties of the CoSi nanowires have been found to be compatible with their thin film counterpart and a high maximum current density of the nanowires has been measured. One way to obtain silicate nanowires has been demonstrated. The silicate compound, which is composed of cobalt, silicon and oxygen, was achieved. The Co silicide/oxide nanocables are potentially useful as a key component of silicate nanowires, interconnects and magnetic units in nanoelectronics.     

制备参数对磁控溅射CoSi2薄膜织构的影响

采用射频磁控溅射法溅射CoSi2合金靶材制备CoSi2薄膜,研究了制备参数对薄膜织构的影响。结果表明,CoSi2薄膜中存在(111)或(220)织构。织构的形成受溅射参数的影响。溅射功率越大,溅射气压越低,(111)织构越强烈。当基底温度增加时,织构经历了先增强后减弱的过程。     

Synthesis of cobalt-based nanocrystal layer in silicon dioxide for nonvolatile memory applications

Cobalt silicide (CoSi) nanocrystal (NC) layer distributed within narrow spatial region is synthesized by thermal annealing of a sandwich structure comprised of a thin cobalt (Co) film sandwiched between two silicon-rich oxide (SiO(x)) layers. It is shown that the size of the CoSi NCs can be controlled by varying the Co film thickness, an increase in the size with increasing thickness. Capacitance-voltage (C-V) measurements on a test metal/oxide/semiconductor (MOS) structure with floating gate based on CoSi NCs of 3.8 nm in diameter and 1.4 x 10(12) cm2 in density are shown to have C-V characteristics suitable for nonvolatile memory applications, including a C-V memory window of about 9.5 V for sweep voltages between -15 V and +8, a retention time >10(8) s, and an endurance > 10(6) program/erase cycles.     

Thin film deposition on plastic substrates using silicon nanoparticles and laser nanoforming

Reduced melting temperature of nanoparticles is utilized to deposit thin polycrystalline silicon (c-Si) films on plastic substrates by using a laser beam without damaging the substrate. An aqueous dispersion of 5 nm silicon nanoparticles was used as precursor. A Nd:YAG (1064 nm wavelength) laser operating in continuous wave (CW) mode was used for thin film formation. Polycrystalline Si films were deposited on flexible as well as rigid plastic substrates in both air and argon ambients. The films were analyzed by optical microscopy for film formation, scanning electron microscopy (SEM) for microstructural features, energy dispersive spectroscopy (EDS) for impurities, X-ray photoelectron spectroscopy (XPS) for composition and bond information of the recrystallized film and Raman spectroscopy for estimating shift from amorphous to more crystalline phase. Raman spectroscopy showed a shift from amorphous to more crystalline phases with increasing both the laser power and irradiation time during laser recrystallization step.     

In-situ high temperature X-ray diffraction study of Co/SiC interface reactions

In situ experiments on the Co/SiC interface reaction were carried out with a high temperature X-ray diffractometer capable of measuring the X-ray diffraction pattern in 1–4s using an imaging plate. The kinetic formation processes of the interface reaction layer were measured in short-period exposure experiments with the apparatus. The time-temperature phase diagram of Co/SiC in N₂was determined. Co₂Si and CoSi were formed at the Co/SiC interface between 921 and 1573 K in N₂. The formation of CoSi obeyed the parabolic rate law. The value of the activation energy was 95 kJ/mol. The results of thermal expansion coefficient measurements suggest that when a sample is cooled to room temperature, compressive strain caused by CoSi occurs on SiC.     

Crystallization of Au-Si/glass thin film: a real-time synchrotron X-ray scattering study

The crystallization of amorphous, Si-rich, Au28Si72/glass thin film was studied in real-time synchrotron X-ray scattering experiments. The amorphous film crystallizes first into Au and Si phases at a low temperature of 206 degrees C. At annealing temperatures above eutectic temperature (T(E) = 360 degrees C), the Au phase melts while the Si phase rapidly grows further. The crystallized Au28Si72 thin film has nanowire-type grains with 1000-nm-length and 10-nm-diameter. We confirm that the Au liquid phase contributes to the low-temperature crystallization of the Si solid phase for Si-nanowire growth.     

Investigation of stress behaviors and mechanism of void formation in sputtered TiSix films

We have investigated the stress behaviors and a mechanism of void formation in TiSi_x films during annealing. TiSi_x thin films were prepared by DC magnetron sputtering using a TiSi_2.1 target in the substrate temperature range of 200–500 °C. The as-deposited TiSi_x films at low substrate temperature (<300 °C) have an amorphous structure with low stress of 1×10⁸ dynes/cm². When the substrate temperature increases to 500 °C, the as-deposited TiSi_x film has a mixture of C49 and C54 TiSi₂ phase with stress of 8×10⁹ dynes/cm². No void was observed in the as-deposited TiSi_x film. Amorphous TiSi_x film transforms to C54 TiSi₂ phase with a random orientation of (311) and (040) after annealing at 750 °C. The C49 and C54 TiSi₂ mixture phase transforms to (040) preferred C54 TiSi₂ phase after annealing over 650 °C. By increasing substrate temperature, the transformation temperature for C54 TiSi₂ can be reduced, resulting in relieved stress of TiSi₂ film. The easy nucleation of the C54 phase was attributed to an avoidance of amorphous TiSi_x phase. We found that amorphous TiSi_x→C54 TiSi₂ transformation caused higher tensile stress of 2×10¹⁰ dynes/cm², resulting in more voids in the films, than C49→C54 transformation. It was observed that void formation was increased with thermal treatment. The high tensile stress caused by volume decreases in the silicide must be relieved to retard voids and cracks during C54 TiSi₂ formation.     

Binary phase spatial modulation using photoinduced anisotropy in amorphous As(2)S(3) thin film

We present a method for binary phase spatial modulation that uses photoinduced anisotropy in a chalcogenide amorphous As(2)S(3) thin film and its application to binary phase-only filters in a VanderLugt optical correlator. The time-dependent light-transmission properties of the photoilluminated As(2)S(3) thin film are analytically examined by use of third-order nonlinear polarization theory. Experimental results on optical correlation are discussed.