衬底对溶胶-凝胶法制备ZnO压电薄膜的影响

采用溶胶-凝胶法分别在晶态衬底Si/SiO2/Ti/Pt和无定形态衬底Si/SiO2上制备了ZnO压电薄膜.以X射线衍射仪和原子力显微镜研究了薄膜的002择优取向度和表面形貌.结果表明,采用溶胶-凝胶法在Si/SiO2/Ti/Pt和Si/SiO2衬底上都能制备出具有较好择优取向,表面粗糙度低的ZnO薄膜,而且由于Pt和ZnO的晶格失配度较小,在Si/SiO2/Ti/Pt衬底上生长的ZnO薄膜形成002择优取向的退火温度低于在Si/SiO2衬底上生长的薄膜形成002择优取向的退火温度.     

AlN薄膜的制备与刻蚀工艺研究

采用直流磁控反应溅射法,在Si(100)和Pt/Ti/Si(100)上制备了具有较好(002)择优取向性的AlN薄膜.采用典型的半导体光刻工艺,利用刻蚀溶液成功地获得了AlN薄膜微图形.较好地解决了AlN薄膜制备与加工中存在的关键问题,为高品质硅基AlN薄膜滤波器的实现奠定了良好的工艺基础.     

应用L-MBE方法制备ZnO薄膜的结构和光学特性

用激光分子束外延(Laser Molecular Beam Epitaxy,L-MBE)设备在p型Si(111)衬底上制备了不同衬底温度和不同氧压的ZnO薄膜,用X射线衍射仪(XRD)和原子力显微镜(AFM)分别对薄膜的结构和形貌进行了分析,用He-Cd激光(325nm)激发的光致发光测试系统对薄膜进行了荧光光谱分析。研究发现,在衬底温度为400℃,氧压1Pa左右所制备的ZnO薄膜表面比较均匀致密,晶粒生长较充分,有较高的结晶质量和发光强度。ZnO薄膜的近带边发射与薄膜的结晶质量和化学配比均有关系。     

厚度效应对Pb(Zr0.53Ti0.47)O3薄膜微结构、铁电、介电性能的影响

用改进的溶胶-凝胶法在Pt(111)/Ti/SiO₂/Si(100)衬底上制备了不同厚度的高度(111)取向的Pb(Zr_0.53Ti_0.47)O₃薄膜.运用X射线衍射(XRD)和原子力显微镜(AFM)分析了薄膜的微结构,原子力显微镜表明厚度为0.3μm和0.56μm的PZT薄膜的晶粒尺寸和表面粗糙度分别为0.2～0.3μm、2～3μm和0.92nm、34nm.0.3μm和0.56μm PZT薄膜的剩余极化(Pr)和矫顽场(Ec)分别为32.2μC/²、79.9kV/cm, 27.7μC/cm²、54.4kV/cm;在频率100KHz时,薄膜的介电常数和介电损耗分别为539、0.066,821、0.029.     

SiN_x和SiN_x/SiO_x薄膜的荧光和红外吸收光谱研究

采用射频磁控溅射法在Si(100)和含有SiOx缓冲层的Si(100)上制备SiNx薄膜。直接生长在Si(100)的SiNx薄膜几乎不发光;而SiNx/SiOx薄膜在650℃以上的高温热处理后有非常强的光致发光,当退火温度为800oC时发光强度达到最高。傅立叶红外吸收研究表明,直接生长在Si(100)的SiNx薄膜在退火后氧化程度略有增加;而SiNx/SiOx薄膜在高温热处理后氧化程度明显升高,但过高温度的退火会导致Si-N键显著减少。分析认为SiNx/SiOx薄膜的发光与Si-N键和Si-O键密切相关。     

ZnO压电薄膜及其SAW滤波器的制备及性能研究

采用磁控溅射方法在Pt/Ti/SiO2/Si衬底上制备了晶化良好的(002)取向的ZnO薄膜,用XRD、SEM表征薄膜的取向和显微结构.在ZnO薄膜上利用剥离技术制备了波长40 μm的AI叉指电极,电极厚度约为200nm,并利用矢量网络分析仪测量了ZnO薄膜声表面波特性,结果显示:声表面波中心频率为146.8MHz,声表面波在ZnO薄膜上的传播速度为5 872m/s.     

采用固相晶化和准分子激光晶化制备结晶硅薄膜的对比

为制备高质量的结晶硅薄膜,以工业玻璃为衬底,利用等离子体增强化学气相沉积工艺制备了非晶硅(α-Si)薄膜,然后分别通过固相晶化和准分子激光晶化两种工艺制备结晶硅(nc-Si)薄膜,采用激光显微拉曼光谱仪、X射线衍射仪和扫描电子显微镜等对两类结晶硅薄膜的结晶率、结晶质量和表面形貌等进行了对比分析。结果表明:采用固相晶化得到的结晶硅薄膜的结晶率约为70%,采用准分子激光晶化得到的结晶率则可达90%;当激光拉曼测试条件变化时,两种结晶硅薄膜的结晶率几乎不变,均处于稳定的晶态结构;采用准分子激光晶化制备的结晶硅薄膜显示出微弱的Si(111)结晶峰位,并具有较大的晶粒尺寸和规则的晶界分布。     

沉积温度对脉冲真空弧源沉积类金刚石薄膜性能的影响

利用脉冲真空弧源沉积技术在Cr17Ni14Cu4不锈钢和Si(100)基体上制备了类金刚石(DLC)薄膜,研究了基体沉积温度对DLC薄膜的性能和结构的影响。研究表明,随着沉积温度由100 ℃提高到400 ℃,DLC薄膜中sp3 键质量分数减少,sp2键质量分数增多,薄膜复合硬度逐渐降低。当DLC薄膜沉积温度达到400 ℃时,薄膜中C原子主要以sp2键形式存在,与沉积温度为100 ℃时制备的DLC薄膜相比,薄膜复合硬度降低50%。DLC薄膜具有优异的耐磨性,摩擦因数低,随着沉积温度由100 ℃提高到400 ℃,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜耐磨性降低。沉积温度为100 ℃时,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜后,耐磨性大幅度提高。DLC薄膜与不锈钢基体结合牢固。     

衬底温度对低温制备铜铟镓硒薄膜结晶性能的影响

采用低温三步共蒸发法在柔性聚酰亚胺衬底上制备了铜铟镓硒(CIGSe)薄膜,利用扫描电子显微镜和X射线衍射仪表征了CIGSe薄膜的结晶质量和晶体结构,探讨了低温沉积工艺中第二步和第三步衬底温度与薄膜晶粒尺寸、织构取向和结晶性能的关系。结果表明:随着第二步和第三步衬底温度同时升高,CIGSe薄膜的晶粒尺寸逐渐增大,镓的两相分离现象逐渐消失;保持第二步衬底温度不变,随着第三步衬底温度进一步升高,CIGSe薄膜的晶粒尺寸继续增大,薄膜的结晶质量显著改善;第二步和第三步衬底温度的变化对CIGSe薄膜的织构取向基本没有影响。     

基于聚酰亚胺柔性衬底微温度传感器阵列的关键技术研究

基于柔性MEMS技术,在聚酰亚胺柔性衬底上成功制作出8×8阵列的铂薄膜电阻微温度传感器.该器件特别适用于复杂几何体高曲率表面温度的实时监控.采用了两种方法制作柔性器件第一种方法是将液态聚酰亚胺旋涂在有氧化物牺牲层的载体硅片上;第二种方法是用胶粘剂将P16051膜暂时粘在载体硅片上,然后分别在两种柔性PI衬底上制作铂薄膜热敏电阻温度传感器,最后将器件从硅片载体上分离下来.采用低温(小于300℃)工艺技术减小了PI柔性衬底的热循环.实验测试结果表明,PI衬底上的铂薄膜热敏电阻具备良好的线性度,其电阻温度系数接近于0.0023/℃.     

Characterization of lead zirconate titanate--lanthanum ruthenate thin film structures prepared by chemical solution deposition

In this work, the results of compositional and microstructural analysis of lead zirconate titanate--lanthanum ruthenate thin film structures prepared by chemical solution deposition are discussed. The cross-section transmission electron microscope (TEM) micrographs of the La-Ru-O film deposited on a SiO2/Si substrate and annealed at 700 degrees C revealed RuO2 crystals embedded in a glassy silicate matrix. When the La-Ru-O film was deposited on a Pt/TiO2/SiO2/Si substrate, RuO2 and La4Ru6O19 crystallized after annealing at 700 degrees C. After firing at 550 degrees C randomly oriented lead zirconate titanate (PZT) thin films crystallized on the La-Ru-O/SiO2/Si substrate, while on La-Ru-O/Pt/TiO2/SiO2/Si substrates PZT thin films with (111) preferred orientation were obtained. No diffusion of the Ru atoms in the PZT film was found. Ferroelectric response of PZT thin films on these substrates is shown in comparison with the PZT film deposited directly on the Pt/TiO2/SiO2/Si substrate without a La-Ru-O layer.     

Arsenic-terminated silicon and germanium surfaces studied by scanning tunnelling microscopy

The epitaxial growth of As on the (111) and (100) faces of Si and the (111) face of Ge has been studied with vacuum tunnelling microscopy. The (111) faces of both semiconductors display a principally 1×1 termination, but differ with the presence of point defects on the Si(111): As-1×1 surface and trenches separating large (～ 100 Å) domains on the Ge(111): As-1×1 surface. I-V characteristics of the tunnel junction show a surface energy gap of approximately 1·9 eV for the Si(111): As-1×1 surface and 0·9 eV for the Ge(111): As-1×1 surface, in good agreement with recent theoretical calculations for these systems. As deposition on Si(001) results in a nominal 2×1 reconstruction of symmetric As dimers and elimination of missing dimer defects characteristic of the native Si(001) 2×1 surface. Further studies on vicinal, double-stepped substrates shows the orientation of the dimers with respect to the substrate depends critically on the substrate temperature during the growth phase, with destruction of the single principle domain surface order occurring at temperatures in excess of 700°C.     

001] zone-axis bright-field diffraction contrast from coherent Ge(Si) islands on Si(001)

Coherent Ge(Si)/Si(001) quantum dot islands grown by solid source molecular beam epitaxy at a growth temperature of 700 degrees C were investigated using transmission electron microscopy working at 300kV. The [001] zone-axis bright-field diffraction contrast images of the islands show strong periodicity with the change of the TEM sample substrate thickness and the period is equal to the effective extinction distance of the transmitted beam. Simulated images based on finite element models of the displacement field and using multi-beam dynamical diffraction theory show a high degree of agreement. Studies for a range of electron energies show the power of the technique for investigating composition segregation in quantum dot islands.     

磁过滤阴极弧法TiN薄膜的制备及其微观机械性能研究

采用“S”型磁过滤阴极弧等离子体沉积技术,室温下在（111）面单晶硅上沉积氮化钛薄膜。采用AFM和XRD技术分别对薄膜的表面形貌和晶体择优取向进行了表征,并用微刻划的方法分析薄膜的微观机械性能。结果表明,薄膜表面光滑致密,随偏压的增大,表面颗粒粒径先增大后减小,并且从（111）面的择优取向转变成（220）面。在刻划实验中,随载荷增加,薄膜先后经历了完全弹性变形,弹-塑性变形和脆性断裂阶段。利用直接和间接2种方法对得到的薄膜的临界载荷进行分析对比,发现在不同负偏压下,薄膜的内应力和临界载荷不同。随着负偏压的增大,薄膜的内应力逐渐增大,临界载荷逐渐减小。在-100V偏压下制备的氮化钛薄膜的微观机械性能最为理想。     

Microscale Friction Behaviour of Single Crystal Si (111) When Rubbed with Diamond Spherical and Conical Styli

An experimental study is described of the friction behaviour of samples of single crystal Si (111) when they were rubbed with diamond spherical (radius of 0.18 mm) and conical styli of included angles of 120° and 136°. Several techniques were used including (1) a reciprocating friction machine, (2) Raman spectroscopy and (3) environmental scanning electron microscopy. Friction force was measured for a constant relative speed of 0.22 mm s^?1 between the rubbing stylus and the substrate. The normal load on the stylus was varied in the range 100–500 mN. In the case of the spherical stylus, the coefficient of friction was in the range 0.03–0.08, whereas for the conical styli, it was up to ten times higher, but it varied with the number of friction cycles. Raman spectroscopy revealed that in all cases, structural phase transitions of the silicon had occurred in the friction tracks and both amorphous silicon and Si-III phases were found. Environmental scanning electron microscope showed no debris in the friction tracks produced by the spherical stylus, whereas a considerable amount of debris was found within the friction tracks produced by the conical styli. This debris has been shown to be responsible for the gradual decrease in the coefficient of friction with increasing number of friction cycles. Calculations of the frictional heating between the spherical stylus and the Si (111) substrate have shown that only a negligible interfacial temperature rise would occur. It has been suggested that, in the absence of ploughing, the coefficient of friction between the spherical stylus and the Si (111) substrate is controlled by the adhesion between the two surfaces, whereas the very initial coefficient of friction between the conical styli and the Si (111) substrate is controlled by the ploughing process.     

Influence of substrate orientation on the morphologyand orientation of LaNiO3 thin films

LaNiO₃ thin films were successfully prepared by a chemical method from citrate precursors. The LNO precursor solution was spin‐coated onto Si (100) and Si (111) substrates. To obtain epitaxial or highly oriented films, the deposited layers were slowly heated in a gradient thermal field, with a heating rate of 1° min^?1, and annealed at 700°C. The influence of different substrate orientations on the thin film morphology was investigated using atomic force microscopy and X‐ray diffraction analysis. Well‐crystallized films with grains aligned along a certain direction were obtained on both substrates. Films deposited on both substrates were very smooth, but with a different grain size and shape depending on the crystal orientation. Films deposited on Si (100) grew in the (110) direction and had elongated grains, whereas those on Si (111) grew in the (211) direction and had a quasi‐square grain shape.     

Degradation, amorphization, and recrystallization of ion bombarded Si(111) surfaces studied by in situ reflection electron microscopy and reflection high energy electron diffraction techniques.

In this paper we report the effect of noble gas ions bombardment on the degradation of atomically flat Si(111) surfaces at room and high (400 degrees C-600 degrees C) temperatures. Reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been used to characterize the topography and structure of the as-implanted and post annealed surface layers. It is shown that the fading of the specularly reflected beam is not directly related to the amorphization of the surface. This experimental study has also evidenced the difficulties one meets to regrow a defect-free material after amorphization by noble gas bombardment. For high temperature for which the amorphization is not possible, the surface loses its stepped structure and turns into a monocrystalline but atomically rough surface. This roughness is a function of substrate temperature.     

The tribological role of surface atoms: ultra-thin carbon and silver layers on the Si(111)

A few monolayers of a carbon film on an Si(111) substrate have been studied for tribological characteristics, focusing on the tribological role of the surface atoms.A monolayer of H and Ag on Si were also tested with a macroscopic diamond slider to examine the effect of the surface atoms on the friction, and it was observed that the sliding systems show an extraordinarily low friction in ultra-high vacuum. We could draw a conclusion: the chemical characteristics of the surface layer strongly affect the friction and nano-scale structures on the surface drastically change the macroscopic slider friction in these systems.