TiN／NbN纳米多层薄膜的交变应力场和超硬效应

为了研究纳米多层薄膜的超硬效应，采用反应溅射法制备从1.4nm至27nm不同调制周期的一系列TiN/NbN纳米多层膜。高分辨电子显微镜参薄膜的调制结构和界面生长方式的观察发现，TiN/NbN膜具有很好的调制结构，并呈现以面心立方晶体结构穿过调制界面外延生长的多晶超晶格结构特征。显微硬度测量表明，TiN/NbN纳米多层膜存在随调制周期变化的超硬效应。薄膜在调制周期为8.3nm时达到HK39.0 Gpa的最高硬度。分析认为，两种不同晶格常数的晶体外延生长形成的交变应力场，对材料有强化作用，这是TiN/NbN纳米多层膜产生超硬效应的主要原因。     

钽基体上铜薄膜微观结构的分子动力学模拟

运用分子动力方法模拟了铜薄膜在钽（100）及（111）基体上沉积过程。结果表明沉积过程中铜薄膜的晶格位向取决于钽基体的晶格位向．在钽（100）面上，铜薄膜在不同的温度下分别沿（111）或（110）面生长，所形成的晶界与住错沿着薄膜的生长方向发展，薄膜表面的粗糙度与沉积温度有关，低温时表面粗糙度较大。而在钽（100）面上，铜薄膜的外延生长面为（100）面，位错沿（111）面分布，并只存在于界面附近，在铜薄膜的内部仅有少量的点缺陷，薄膜表面粗糙度较小并与沉积温度无关。     

等离子体浸没离子注入和沉积技术制备TiN薄膜研究

利用多功能等离子体浸没离子注入设备，采用等离子体浸没离子注入和沉积技术在Ti合金表面制备具有优异力学性能的TiN薄膜。研究了真空室中氮气存在状态及氮气压力对薄膜性能的影响：当氮以中性气体存在于真空室中，薄膜的生长主要受热力学因素控制，沿着低自由能的密排面(低指数面)TiN(111)择优生长；当氮以等离子体状态存在于真空室中，薄膜沿着高指数面TiN(220)择优生长，具有高硬度、耐磨性好的优点，并且随着N分压的提高，薄膜耐磨性提高。     

纳米晶粒受控生长抑制PZNT铁电薄膜中异相形成

在LaAlO3（001）、MgO（001）、SrTiO3（001）衬底以及SrTiO3（001）／PZT（001）种膜上用液相外延方法生长了PZNT薄膜。生长结果表明：在LaAlO3（001）基片PZNT晶粒以三维岛状自发生长。薄膜中有大量的焦绿石异相；在MgO（001）和SrlriO3（001）衬底上，为三维岛状异质外延生长。薄膜中焦绿石异相几乎消失；引入[001]取向的PZT种膜后，岛状三维生长变为二维生长，显著改善了外延膜的质量，获得了完整的PZNT膜。分析了衬底取向对紧邻层纳米尺寸范围的晶粒形成、薄膜晶粒的发育、克服薄膜中异相形成等的影响，总结了获得完整PZNT薄膜的生长条件。     

TiN/NbN纳米多层薄膜的交变应力场和超硬效应

为了研究纳米多层薄膜的超硬效应 ,采用反应溅射法制备从 1 4nm至 2 7nm不同调制周期的一系列TiN/NbN纳米多层膜。高分辨电子显微镜对薄膜的调制结构和界面生长方式的观察发现 ,TiN/NbN膜具有很好的调制结构 ,并呈现以面心立方晶体结构穿过调制界面外延生长的多晶超晶格结构特征。显微硬度测量表明 ,TiN/NbN纳米多层膜存在随调制周期变化的超硬效应。薄膜在调制周期为 8 3nm时达到HK39 0GPa的最高硬度。分析认为 ,两种不同晶格常数的晶体外延生长形成的交变应力场 ,对材料有强化作用 ,这是TiN/NbN纳米多层膜产生超硬效应的主要原因     

Si(111) 衬底上3C-SiC的超低压低温外延生长

研究了发展一种Si衬底上低温外延生长3C－SiC的方法。采用LPCVD生长系统，以SiH4和C2H4为气源，在超低压（30Pa) ,低温（900℃）的条件下，在Si(111衬底上外延生长出高质量的3C－SiC薄膜材料。采用俄歇能谱（AES），X射线衍射（XRD）和原子力显微镜（AFM）等分析手段研究了SiC薄膜的外延层组分，晶体结构及其表面形貌。AES结果表明薄膜中的Si/C的原子比例符合SiC的理想化学计量比，XRD结果显示了3C－SiC外延薄膜的良好晶体结构，AFM揭示了3C－SiC薄膜的良好的表面形貌。     

等离子体浸没离子注入和沉积技术制备TiN薄膜研究

利用多功能等离子体浸没离子注入设备 ,采用等离子体浸没离子注入和沉积技术在Ti合金表面制备具有优异力学性能的TiN薄膜。研究了真空室中氮气存在状态及氮气压力对薄膜性能的影响 :当氮以中性气体存在于真空室中 ,薄膜的生长主要受热力学因素控制 ,沿着低自由能的密排面 (低指数面 )TiN(1 1 1 )择优生长 ;当氮以等离子体状态存在于真空室中 ,薄膜沿着高指数面TiN(2 2 0 )择优生长 ,具有高硬度、耐磨性好的优点 ,并且随着N分压的提高 ,薄膜耐磨性提高     

MoS2基板上外延生长C60薄膜的分子动力学模拟

外延生长异质薄膜通常要求材料之间晶格匹配，然而利用范德瓦尔斯作用外延生长时，晶格匹配要求显降低实验上已经得出了在MoS2基板上外延生长C60薄膜的结果，本用分子动力学计算机模拟方法对MoS2基板上外延生长C60薄膜进行了研究，证实范德瓦尔斯外延可以克服较大的晶格失配问题。     

MoS2基板上外延生长C60薄膜的分子动力学模拟

外延生长异质薄膜通常要求材料之间晶格匹配 ,然而利用范德瓦尔斯作用外延生长时 ,晶格匹配要求显著降低。实验上已经得出了在MoS2 基板上外延生长C60 薄膜的结果 ,本文用分子动力学计算机模拟方法对MoS2 基板上外延生长C60 薄膜进行了研究 ,证实范德瓦尔斯外延可以克服较大的晶格失配问题。     

TiN薄膜的循环制备和电学性质

用金属有机物化学气相淀积（Metal Organic Chemical Vapor Deposition，MOCVD）制备了TiN薄膜，通过不同循环制备的、厚度相同的平面薄膜电阻率的比较研究了TiN薄膜的电学性质．结果表明，多次循环会引入界面而增大电阻率，与薄膜成分和微结构分析的结果一致．得到了单循环的最优厚度以使样品电阻率最低．通过相同循环、不同厚度样品在真实器件中电学性能的比较，发现介窗（Via）直径越小，TiN薄膜对介窗电阻的影响越大．     

Interface structure of deposited GaSb on GaAs (001): Monte Carlo simulation and experimental study

The growth of GaSb thin films by MBE on GaAs (001) is investigated experimentally, using TEM, and theoretically, using KMC simulations. The atomic scale mechanisms inherent to the growth are discussed and described in the KMC model in which the strain is introduced through an elastic energy term based on a valence force field approximation. We observe that the first two monolayers of the deposited films form strained three-dimensional clusters, but further deposition induces film relaxation and rough 3D growth with valley formation presenting (111) facets with unstable bottoms. We show that the roughening morphology and creation of grooves during growth are in agreement with experimental TEM observations.     

An overview of spatial microscopic and accelerated kinetic Monte Carlo methods

The microscopic spatial kinetic Monte Carlo (KMC) method has been employed extensively in materials modeling. In this review paper, we focus on different traditional and multiscale KMC algorithms, challenges associated with their implementation, and methods developed to overcome these challenges. In the first part of the paper, we compare the implementation and computational cost of the null-event and rejection-free microscopic KMC algorithms. A firmer and more general foundation of the null-event KMC algorithm is presented. Statistical equivalence between the null-event and rejection-free KMC algorithms is also demonstrated. Implementation and efficiency of various search and update algorithms, which are at the heart of all spatial KMC simulations, are outlined and compared via numerical examples. In the second half of the paper, we review various spatial and temporal multiscale KMC methods, namely, the coarse-grained Monte Carlo (CGMC), the stochastic singular perturbation approximation, and the τ-leap methods, introduced recently to overcome the disparity of length and time scales and the one-at-a time execution of events. The concepts of the CGMC and the τ-leap methods, stochastic closures, multigrid methods, error associated with coarse-graining, a posteriori error estimates for generating spatially adaptive coarse-grained lattices, and computational speed-up upon coarse-graining are illustrated through simple examples from crystal growth, defect dynamics, adsorption–desorption, surface diffusion, and phase transitions.     

Sublimation growth of titanium nitride crystals

The sublimation-recondensation growth of titanium nitride crystals with N/Ti ratio of 0.99 on tungsten substrates is reported. The growth rate dependence on temperature and pressure was determined, and the calculated activation energy was 775.8 ± 29.8 kJ/mol. The lateral and vertical growth rates changed with the time of growth and the fraction of the tungsten substrate surface covered. The orientation relationship of TiN (001) || W (001) with TiN [100] || W [110], a 45° angle between TiN [100] and W [100], occurs not only for TiN crystals deposited on (001) textured tungsten but also for TiN crystals deposited on randomly orientated tungsten. This study demonstrates that this preferred orientational relationship minimizes the lattice mismatch between the TiN and tungsten.     

Initial growth of TiN on different phases of high speed steel

High speed steel is a complex substrate material consisting of various phases including metal carbides such as MC and M₆C. The MC carbides, which mainly consists of VC_0.8, have the same crystal structure as TiN (NaCl B1) and a similar lattice parameter (4.16 Å) to that (4.24 Å) for TiN. Different nucleation and growth modes can thus be expected on the various phases during growth of TiN thin films. For example, on the MC carbides a local epitaxial growth can be expected. Deposition of TiN layers 40–60 nm thick by d.c. magnetron sputtering was carried out onto electrolytically thinned steel substrates for transmission electron microscopy examination. The substrate temperature was varied between 310 and 920 K. Air-exposed substrates were deposited with and without sputter etching. Examination of the as-deposited films shows fine equiaxed grains of TiN on the substrate that was not sputter etched. On the sputter-etched substrate, TiN grew epitaxially on the MC carbides and with fine equiaxed grains on the surrounding steel matrix. The size and number of TiN grains per unit area were the same for the non-sputter-etched substrates and for the steel matrix in the sputter-etched substrates. The carbide grains are randomly oriented and distributed in the steel matrix. Epitaxial growth of TiN is observed on the six most densely packed lattice planes of the MC carbides.     

Microstructure and optical properties of cubic AlN/TiN bilayers deposited by laser molecular beam epitaxy

AlN/TiN bilayers were deposited on Si(100) substrates with varying laser pulse energy by laser molecular beam epitaxy (LMBE) technique, and their growth mode, crystal structure and optical properties were investigated. The results indicated that atomically flat TiN single films and AlN/TiN bilayers with layer-by-layer growth mode were successfully grown on Si(100) substrates at optimal laser pulse energy. Both TiN and AlN in the grown bilayers exhibited the NaCl-type cubic structure with the same (200) preferred orientation, showing an excellent epitaxial relationship. TiN single film was more reflective in the infrared range and presented a small transparent window centered at wavelength of 404 nm. Reflectance spectrum of AlN film on top of TiN indicated the sharp absorption at about 246 nm, yielding a bandgap energy of 5.04 eV comparable to the theoretical calculation of bulk cubic AlN, but scarcely reported by the experimental data.     

Cu-Zn掺杂对TiN复合膜层组织性能的调制

利用磁控溅射方法在不锈钢表面沉积了Cu-Zn掺杂TiN复合膜, 研究不同的Cu、Zn含量对膜层结构和性能(硬度、耐磨性能以及耐腐蚀性能)的影响. 结果表明, 掺杂的Cu、Zn可以阻止TiN晶粒生长, 随掺杂量增加TiN晶粒细化, Cu、Zn含量比较高时由于金属相长大而使膜层组织粗化. 当Cu≤10.38at%, Zn≤2.19at%时, TiN以(111)晶向择优生长, 且随掺杂量增加TiN(200)晶向逐渐增强. XPS结果表明膜层主要由TiN和单质Cu组成. 当掺杂Cu为10.38at%、Zn为2.19at%时,复合膜具有较高的硬度和较好的耐磨性能. 尽管耐腐蚀性能随着Cu、Zn含量的增加而下降, 但少量的Cu-Zn掺杂可显著提高膜层钝化能力.     

Epitaxial growth of MgO/TiN multilayers on Cu

The growth of epitaxial MgO/TiN multilayer films on (001) Cu has been investigated. In particular, epitaxial structures were grown on (001) Cu layers that were epitaxial on (001) SrTiO₃. X-ray diffraction and reflection high-energy electron diffraction indicate that the multilayer structures are epitaxial on the (001) Cu surface. The motivation is the use of crystalline MgO/TiN multilayers as a diffusion barrier to both copper and oxygen. MgO/TiN multilayers are potentially useful as diffusion barriers for Cu interconnects on semiconductors as well as for superconducting wires based on the epitaxial growth of cuprate superconductors on biaxially textured copper.     

Coherent growth and superhardness effect of AlN/TiN nanomultilayers

The formation of metastable cubic AlN (c-AlN) and its effect on the mechanical properties of AlN/TiN nanomultilayers were studied. A series of AlN/TiN multilayers with different modulation periods were prepared by reactive magnetron sputtering. The microstructure and mechanical properties of multilayers were characterized with low-angle X-ray diffraction, transmission electron microscopy and a microhardness tester. The results show that AlN exists as a metastable cubic phase in multilayers at small modulation periods due to the “template effect” of TiN layer and forms superlattice with TiN through coherent epitaxial growth. Correspondingly, multilayers show the superhardness effect with the enhancement of hardness at small modulation periods. With the increase of modulation periods, AlN layer grows as c-AlN firstly and then its stable hexagonal structure (h-AlN) appears and grows on the already formed c-AlN. Correspondingly, the hardnesses of the multilayers decrease. The change of properties with the formation of c-AlN and the alternative strain field resulting from coherent growth of c-AlN and TiN are likely reasons for the superhardness effect of AlN/TiN multilayers.     

A new approach to modelling,control and simulation of knowledgeable manufacturing cell

The running of the knowledgeable manufacturing cell (KMC) is a typical discrete event dynamic process. Methods used to model and analyse discrete event dynamic systems (DEDS) include Petri net and automata theory. In this paper, a new matrix-automaton is proposed to model the KMC and solve the task control problems existing in the KMC. The automaton is of structured property and can be used to analyse the dynamic performance of the KMC. Stochastic dynamic programming is used to derive the optimal task control strategy of the automaton, and a simulation method and program are proposed to simulate the running of the KMC. The matrix-automaton model of an experimental KMC including m manufacturing agents and n classes of workpieces is built and solved by the methods in this paper. Compared with the random control principle, the objective function value of the control strategy in this paper is obviously lower, which testifies the validity and feasibility of the control strategy.     

Epitaxial growth of SrTiO3 films with different orientations on TiN buffered Si(001) by pulsed laser deposition

Epitaxial SrTiO₃ (STO) films have been grown on TiN buffered Si(001) by pulsed laser deposition. The TiN layer was in situ deposited at 540, 640 or 720°C whereas the STO film was grown at a fixed temperature of 640°C. We have studied the effect of the growth temperature of TiN on the epitaxial relationship of STO/TiN heterostructures. It is found that for TiN grown at 540 or 640°C the epitaxial relationship is 001STO 001TiN, and for TiN grown at 720°C it changes to (101)STO (001)TiN and [ 01]STO [1 0]TiN (or [ 01]STO [110]TiN). This change of relationship is accompanied by a sharp reduction in the out-of-plane lattice constant of the TiN layer. Fourier transform infrared spectra show that the longitudinal optic modes are active for all the STO films, but the absorption peak associated with the transverse optic mode is observed only in the (101) oriented STO films.