Structure and internal stress of Au films deposited on SiO2／Si（100） andmica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200] and [311] are slightly more than those of [111] and [220]. An internal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]-and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiOJSi(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

多晶SiC/多孔硅结构材料的APCVD生长及表征

采用SiH₄-C₃H₈-H₂气体反应体系,通过常压化学气相淀积(APCVD)工艺在电化学腐蚀的多孔硅衬底上进行了多晶3C-SiC薄膜的生长,研究了多孔硅孔隙率对薄膜生长质量的影响．实验结果表明,当多孔硅孔隙率较低时,得到的是含有SiC(111)晶粒的多晶硅薄膜,随着孔隙率的增加,生长薄膜由富碳多孔SiC向多晶SiC薄膜过渡,表面平整度增加,并具有<111>晶向择优生长的特点．     

双AlN插入层法在Si图形衬底上进行AlGaN/GaN HEMT的MOCVD生长

双AlN插入层方法被用来在Si（111）图形衬底上进行AlGaN/GaN高迁移率晶体管（HEMT）的金属有机物化学气相沉积（MOCVD）外延生长。Si图形衬底采用SiO2掩膜和湿法腐蚀（无掩膜）两种方法进行制备。高温生长双AlN插入层用来释放GaN外延层和Si衬底之间由于晶格失配和热失配而产生的张应力。AlGaN/GaN HEMT的生长特性被讨论和分析。在使用优化的双AlN插入层之前,可以在图形[1-100]方向观察到比[11-20]方向更多的由于应力而引起的裂纹。这是由于GaN在（1-100）面比（11-20）更稳定。建议在图形设计中,长边应沿着[11-20]方向进行制备。拉曼测试显示在图形凹角处比凸角处有更大的拉曼频移,证明在图形凹角处有更大的张应力。     

Research of Current Mode Atomic Force Microscopy (C-AFM) for Si/SiC Heterostructures on 6H-SiC(0001)

Si/SiC heterostructures with different growth temperatures were prepared on 6 HSiC(0001) by LPCVD. Current mode atomic force microscopy and transmission electron microscopy were employed to investigate the electrical properties and crystalline structure of Si/SiC heterostructures. Face-centered cubic(FCC) on hexagonal close-packing(HCP) epitaxy of the Si(111)/SiC(0001) heterostructure was realized at 900°C. As the growth temperature increases to1 050°C, the 110 preferred orientation of the Si film is observed. The Si films on 6 H-SiC(0001)with different growth orientations consist of different distinctive crystalline grains: quasi-spherical grains with a general size of 20 μm, and columnar grains with a typical size of 7 μm×20 μm. The electrical properties are greatly influenced by the grain structures. The Si film with 110 orientation on SiC(0001) consists of columnar grains, which is more suitable for the fabrication of Si/SiC devices due to its low current fluctuation and relatively uniform current distribution.     

衬底效应对LiTaO3薄膜制备的影响

用溶胶凝胶法在N型硅、P型硅、石英、铂、镍衬底上制备了钽酸锂(LiTaO3)薄膜,用XRD和SEM对钽酸锂薄膜性能参数进行了表征;发现掺杂少量环氧树脂能提高钽酸锂薄膜的均匀性,改善薄膜与衬底的粘附性;研究了衬底效应与薄膜厚度的关系,薄膜厚度超过0.2 μm,Ni衬底的XRD峰值强度几乎不再出现,说明衬底对薄膜初始结晶取向有重要影响;利用不同衬底上生长钽酸锂薄膜,XRD研究结果表明:N型硅、P型硅、石英衬底上只能制备多晶钽酸锂薄膜,铂衬底上制备的钽酸锂薄膜在(012)晶向有强大的择优取向性,镍衬底上制备的钽酸锂薄膜有更好的C轴择优取向性,C轴择优取向系数可达0.082。     

Microstructures and magnetic properties of [SiO2/FePt]5/Ag thin films

[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.     

Si(111)和Si(100)衬底上磁控反应溅射制备AlN薄膜

采用射频磁控反应溅射法在Si(111)和Si(100)两种衬底上制备了AlN薄膜,用X射线衍射(XRD)对AlN薄膜进行了表征,研究了衬底Si(111)、Si(100)取向以及N2百分比对AlN(002)薄膜c-轴择优取向的影响。实验结果表明,Si(100)较适合生长c-轴择优取向AlN薄膜,而且N2百分比为40%时,AlN薄膜的c-轴取向最好,具有尖锐的XRD峰,此时对应于AlN(002)晶向。计算了(002)取向AlN和两种Si衬底的失配度,Si(111)面与AlN(002)面可归结为正三角形晶系之间的匹配,失配度为23.5%;而Si(100)面与AlN(002)面可归结为正方形晶系与正三角形晶系之间的匹配,失配度为0.8%,可以认为完全共格。理论分析和实验结果相符。     

Different properties of GaN-based LED grown on Si(111) and transferred onto new substrate

Nitride light-emitting diodes (LEDs) based on silicon substrate have been extensively studied[1―4]. However, it is difficult to grow high-quality nitride epilayers on Si substrate due to not only the large mismatch of lattice and thermal expansion coefficient between the epilayer and substrate, but also the SixNy will be generated during the growth process. Although it has so many obstacles to obtain satisfied GaN MQW LEDs on Si substrate, some excellent results have been achieved recen…     

Effect of Mg-film thickness on the formation of semiconductor Mg2Si films prepared by resistive thermal evaporation method

Mg fi lms of various thicknesses were deposited on Si(111) substrates at room temperature by resistive thermal evaporation method, and then the Mg/Si samples were annealed at 40 ℃ for 4 h. The effects of Mg fi lm thickness on the formation and structure of Mg2Si fi lms were investigated. The results showed that the crystallization quality of Mg2Si fi lms was strongly infl uenced by the thickness of Mg fi lm. The XRD peak intensity of Mg2Si(220) gradually increased initially and then decreased with increasing Mg fi lm thickness. The XRD peak intensity of Mg2Si(220) reached its maximum when the Mg fi lm of 380 nm was used. The thickness of the Mg2Si fi lm annealed at 400 ℃ for 4 h was approximately 3 times of the Mg fi lm.     

Structural and physical properties of permalloy thin films prepared by DC magnetron sputtering at different substrate temperature

Permalloy Ni80Fe20 films have been grown on thermal oxidized Si (111) wafers by magnetron sputtering at well-controlled substrate temperatures of 300, 500, 640 and 780 K in 0.65 Pa argon pressure. The base pressure was about 1×10-4 Pa. The deposition rate was about 5 nm/min for all the films. The structure of the films was studied using X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the films was analyzed using scanning Auger microprobe. The resistance and magnetoresistance of the films were measured using four-point probe technique. The results show that the content of oxygen in the films decreases gradually with raising substrate temperature. In addition, the surface morphology of the films presents notable change with the increasing of the substrate temperature; the residual gases and defects decrease and the grains have coalesced evidently, and then the grains have grown up obviously and the texture of (111) orientation develops gradually in the grow     

Size- and temperature-dependent Young’s modulus and size-dependent thermal expansion coefficient of nanowires

Nanowires(NWs) exhibit size-dependent mechanical properties due to the high surface/volume ratio, in which temperature also plays an important role. The surface eigenstress model is further developed here to quantitatively predict the size-dependent mechanical properties of NWs and results in analytic formulas. Molecular dynamics(MD) simulations are conducted to study the size-dependent mechanical of [100], [110] and [111] Ni and Si nanowires within the temperature range of 100–400 K and the MD results verify perfectly the newly developed surface eigenstress model.     

Al-induced Lateral Crystallization of Amorphous Si Thin Films by Microwave Annealing

Al-induced lateral crystallization of amorphous silicon thin films by micr owave annealing is investigated,The erystallized Si films are examined by optical microscopy,Raman spectroscopy ,transimission electron microscopy and transmission electron diffraction micrography.After microwave annealing at 480 ℃ for 50min the amorphous Si is completely cystallized with lagrge grains of main (111) orientation,The rate of lateral crystallization is 0.04μm/min,This process,labeled MILC-MA ,not only lowers the temperature but also reduces the time of crystallization.The crystallization.mechanism during microwave annealing and the electrical properies of polycrystalline Si thin films are analyzed.This MILC-MA process has potentila application in large area electronics.     

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.     

Interface structure between epitaxial NiSi2 and Si

The interface structure between the Si and NiSi2 epitaxially grown on the （112） Si substrate was studied using high resolution transmission electron microscopy and computer image simulation. The results showed that the interface between Si and NiSi2 epitaxially grown on the （ 112 ） Si substrate has six different types： type A NiSi2 （111 ）/（ 111 ） Si, type A NiSi2 （001）/（001） Si, type B NiSi2 （ 111 ）/（ 111） Si, type B NiSi2 （ 112 ）/（ 1 12 ） Si, type B NiSi2 （ 271 ）/（001） Si, and type B NiSi2 （ 114 ）/（ 110 ） Si. And there are one or more different atomic structures for one type of interface.     

低温生长SiO_2膜的性质及其在SiGe/Si HBT研制中的应用

用磁控溅射SiO2膜作为台面SiGe／SiHBT的表面保护纯化膜和光刻掩膜．测试分析了溅射工艺对SiO2膜的性质和SiGe／SiHBT性能的影响．研究发现,较高的衬底温度（200℃）有得于改善SiO2膜的质量．用溅射SiO2方法制备的HBT的电流增益明显高于用热分解正硅酸乙脂方法淀积SiO2制备的HBT．这说明溅射法避免了高温引起SiGe层应变驰豫所造成的HBT性能变差．     

磁控溅射法生长ZnO薄膜的结构和表面形貌特性

采用射频磁控溅射方法,在Si（111）和玻璃基片上制备ZnO薄膜。研究衬底温度和基片类型对薄膜结构、表面形貌的影响。结果显示,所有ZnO薄膜沿c轴择优生长,同种基片类型上生长的薄膜,随着衬底温度升高,（002）衍射峰强度和表面粗糙度增高;相同衬底温度下生长的ZnO薄膜,Si基片上制备的薄膜（002）衍射峰强度和表面粗糙度小于玻璃片上的。基片类型影响薄膜应力状态,玻璃片上制备的ZnO薄膜处于张应变状态,Si基片上的薄膜处于压应变状态;对于同种基片类型上生长的ZnO薄膜,衬底温度升高,应力减小。Si衬底上、300℃下沉积的薄膜颗粒尺寸分布呈正态。     

Growth,Characterization and Micro-pattern Fabrication of Iridium/Si3N4/Si（100） Thin Films

Iridium thin films have been deposited on Si3N4（100 nm）/Si（100） substrates by magnetron sputtering. And then iridium film micro-patterns were fabricated by ion milling technique. The atomic force microscopy （AFM） measurements reveal that there is a very fiat and smooth surface with an average roughness of 0.64 nm for the iridium films. The X-ray diffraction also reveals that the deposited iridium films have a polycrystalline microstructure with （111） plane preferential orientation. The electrical resistivity of the iridium films was also measured and discussed.     

高锰TWIP钢拉伸时织构演变和孪生弱化织构的作用

研究室温下锰的质量分数分别为26%和30%的两种晶粒较粗大的TWIP钢拉断过程中织构的演变规律及孪生弱化〈111〉织构的作用。结果表明,TWIP钢拉伸时形成较强的〈111〉织构,也形成由〈111〉取向晶粒的不同孪晶产生的接近〈100〉的弱织构,从而孪生弱化了〈111〉拉伸织构。粗的奥氏体晶粒促进孪生,从而加速〈111〉织构的弱化。拉伸过程中〈111〉取向的晶粒有利于形变孪生,〈100〉取向的晶粒不利于孪生。锰含量较低的26Mn钢出现少量的形变诱发ε-M,由于ε-M主要从〈111〉取向的形变孪晶内形成,因此也出现择优取向,形成倾转的基面织构,弱化了〈111〉织构。     

Sputtering of ZnO buffer layer on Si for GaN blue light emitting materials

The preparation of high quality ZnO/Si substrates for the growth of GaN blue light emitting materials is considered. ZnO thin films have been deposited on Si (100) and Si (111) substrates by conventional magnetron sputtering. Morphology, crystallinity and c-axis preferred orientation of ZnO thin films have been investigated by transmitting electron microscopy (TEM), X-ray diffraction (XRD) and X-ray rocking curve (XRC). It is proved that the ZnO thin films have perfect structure. The full-width-at-half-maximum (FWHM) of the ZnO(002) XRC of these films is about 1°, while the minimum is 0.353°. This result is better than the minimum FWHM (about 2°) reported by other research groups. Moreover, comparison and discussion are given on film structure of ZnO/Si(100) and ZnO/Si(111).     

[Si,O,C,P]自由基的结构和生成路径

在密度泛函和从头算的理论下,研究了双重态[Si,O,C,P]自由基的结构和生成路径。在B3LYP/6-311G(d)水平下,计算得到13个异构体和15个过渡态。在QCISD/6-311G(d)水平下,环状结构的O-cCSiP5和两个弯曲的异构体OSiCP1和SiCPO3是动力学稳定的异构体。三个异构体的价键结构和异构体1和5可能的生成路径被讨论。预测的结构和生成路径对[Si,O,C,P]自由基将来的实验室制备和星际探测具有帮助作用。