Substrate dependent structural and magnetic properties of pulsed laser deposited Fe3O4 thin films

Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, MgO(100), and Si(100) by pulsed laser deposition technique using excimer KrF laser (248 nm). The orientations, crystallite size and lattice parameters were studied using X-ray diffraction. The XRD results show that the films deposited on MgO and Si substrates are highly oriented and show only (400) and (311) reflections respectively. On the other hand, the orientation of the films deposited on quarts substrate changed from (311) to (400) with an increase in the substrate temperature from 400 degrees C to 600 degrees C, indicating thereby that the film growth direction is highly affected with nature of substrate and substrate temperature. The surface morphology of the deposited films was studied using Atomic Force Microscopy (AFM) and spherical ball like regular features of nanometer size grains were obtained. The magnetic properties were studied by Superconducting Quantum Interference Device (SQUID) magnetometer in the magnetic field +/- 6 Tesla. The magnetic field dependent magnetization (M-H) curves of all the Fe3O4 thin films measured at 5 K and 300 K show the ferrimagnetic nature. The electrochemical sensing of dopamine studied for these films shows that the film deposited on MgO substrate can be used as a sensing electrode.     

玻璃衬底和Si衬底制备的Zn0.96Nd0.04O薄膜的结构研究

通过射频磁控溅射技术在玻璃衬底和Si（111）村底上制备了Zn0.96Nd0.04O薄膜。XRD分析表明,Zn0.96Nd0.04O薄膜是具有C轴择优生长的纳米多晶薄膜,Nd以替位原子的形式存在于ZnO晶格,Nd掺杂没有改变ZnO晶格结构。从AFM图中看出,薄膜表面形貌较为粗糙,Si衬底薄膜的晶粒具有规律且晶粒尺寸大于玻璃衬底。     

热丝CVD法低温制备的多晶硅薄膜质量对衬底依赖性的研究

以SiH4和H2作为反应气体,采用HWCVD的方法分别在石英玻璃、AZO、Si（100）和Si（111）衬底上制备了多晶硅薄膜。利用X射线衍射（XRD）,拉曼（Raman）光谱和傅里叶红外（FT-IR）吸收光谱研究了不同衬底对多晶硅薄膜的择优取向、晶化率和应力的影响,用SEM观察了多晶硅薄膜的表面形貌。研究发现在4种衬底上生长的多晶硅薄膜均为（111）择优取向。单晶硅片对多晶硅薄膜有很强的诱导作用,并且Si（111）的诱导作用优于Si（100）的诱导作用。AZO对多晶硅薄膜生长也有一定的诱导作用。通过计算薄膜晶态比,得到除以石英为衬底的样品外,其它3种样品的晶态比均在90%以上,尤其以单晶硅片为衬底的样品更高。石英玻璃、AZO和Si（100）上生长的多晶硅薄膜中均存在压应力。     

RF溅射稀土掺杂ZnO薄膜的结构与发光特性

通过射频磁控溅射技术在Si(111)衬底上制备了未掺杂和La、Nd掺杂ZnO薄膜.XRD分析表明,ZnO薄膜具有c轴择优生长,La、Nd掺杂ZnO薄膜为纳米多晶薄膜.AFM观测,La、Nd掺杂ZnO薄膜表面形貌较为粗糙.从薄膜的室温光致光谱中看到,所有薄膜都出现了395 nm的强紫光峰和495 nm的弱绿光峰,La掺杂ZnO薄膜的峰强度增大,Nd掺杂ZnO薄膜的峰强度减弱,分析了掺杂引起PL峰强度变化的原因.     

ZnO/SiC/Si异质结构的特性

用MOCVD方法在p型单晶Si（100）基片上外延SiC层,再用直流溅射在SiC层上生长ZnO薄膜,制备出ZnO／SiC／Si异质结构,用XRD和AFM分析了ZnO／SiC／Si和ZnO／Si异质结构中表层ZnO的结构和形貌的差别,研究了这种异质结构的特性．结果表明,在Si（100）基片上外延生长出的是高取向、高结晶质量的SiC（100）层．这个SiC层缓冲层使在Si基片上外延生长出了高质量ZnO薄膜,因为ZnO与SiC的晶格失配比ZnO与Si的晶格失配更低．     

Influence of Sputtering Pressure on the Structure and Mechanical Properties of Nanocomposite Ti-Si-N Thin Films

Nanocomposite Ti-Si-N thin films have been deposited on Si (100) substrate by direct current/radio frequency (DC/RF) magnetron sputtering. The effect of varying deposition parameters on the structure and mechanical properties of Ti-Si-N films has been investigated by characterization techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and nanoindentation, respectively. XRD analysis of the thin films exhibit all (111), (200) and (220...     

Nano-cube MgO formed on silicon substrate using pulsed laser deposition

Nano-cube MgO particles were formed on Si substrates by deposition of an MgO target using pulsed laser deposition method. An epitaxial film grows on Si(001) substrate with its contraction of lattice constants. In this study, expecting high quality MgO film, the MgO film prepared in the oxygen pressure ranging from 75-400 mTorr at the high temperature of -750 degrees C. The deposited MgO showed the growth of (001) preferred orientation on the Si(001) substrate. However, X-ray Photoelectron Spectroscopy (XPS) indicated the MgO film did not form a continuous film on the Si surface. Interestingly, the surface morphology observed by an Atomic Force Microscopy (AFM) showed nano-cube MgO particles scattered on the smooth surface of Si substrate. After annealing the nano-cube MgO, the shape of MgO particles were changed from nano-cube to round shaped particles. The AFM image of the surface showed round shaped MgO nanoparticles scattered on rough surface. X-ray Diffraction (XRD) revealed the epitaxial growth of MgO(001) with cubic on cubic arrangement on the Si(001) substrate (MgO[100] parallel to Si[100]).     

Growth and characterization of La5/8Sr3/8MnO3 thin films prepared by pulsed laser deposition on different substrates

Colossal magnetoresistance La_5/8Sr_3/8MnO₃ (LSMO) thin films were directly grown on MgO(100), Si(100) wafer and glass substrates by pulsed laser deposition technique. The films were characterized using X-ray diffraction (XRD), field emission-scanning electron microscope and atomic force microscopy (AFM). The electrical and magnetic properties of the films are studied. From the XRD patterns, the films are found to be polycrystalline single-phases. The surface appears porous and cauliflower-like morphology for all LSMO films. From AFM images, the LSMO films deposited on glass substrate were presented smooth morphologies of the top surfaces as comparing with the films were deposited on Si(100) and MgO(100). The highest magnetoresistance (MR) value obtained was ?17.21 % for LSMO/MgO film followed by ?15.65 % for LSMO/Si and ?14.60 % for LSMO/Cg films at 80 K in a 1T magnetic field. Phase transition temperature (T_P) is 224 K for LSMO/MgO, 200 K for LSMO/Si and above room temperature for films deposited on glass substrates. The films exhibit ferromagnetic transition at a temperature (T_C) around 363 K for LSMO/MgO, 307 K for LSMO/Si and 352 K for LSMO/Cg thin film. T_C such as 363 and 352 K are the high T_C that has ever been reported for LSMO films deposited on MgO substrate with high lattice mismatch parameter and glass substrates with amorphous nature.     

The effect of titanium current on structure and hardness of aluminium titanium nitride deposited by reactive unbalanced magnetron co-sputtering

Nanocrystalline aluminium titanium nitride (AlTi₃N) thin films were deposited on Si (100) wafer and grid substrates without external heating and biasing at room temperature by reactive unbalanced magnetron co-sputtering technique using pure individual titanium and aluminium targets. The effects of titanium current (I_Ti) on the structure and hardness of these films have been studied. The films were sputtered with Ar and N₂ gases flow rate of 8 and 4 sccm, respectively. The sputtering current of the aluminium current (I_Al) was kept at 600 mA and the sputtering current of titanium (I_Ti) was varied from 600 to 800 mA. The films were deposited for different deposition times ranging from 15 to 60 min. The deposited films were then characterized and analyzed by X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and nanoindentation measurement. The results indicated that the modification of the crystal structure, surface morphology and microstructure were dependent on the deposition parameters. The XRD patterns show polycrystalline structure with preferred orientations in (112), (004) and (153) planes which agree with the standard structure of aluminium titanium nitride (AlTi₃N) films. In addition, the structure of AlTi₃N was also confirmed by TEM. These results show that the films are composed of high Al content. The root mean square surface roughness and the average thicknesses were strongly influenced by I_ti and deposition times. Cross section analysis by SEM showed dense and compact columnar morphology. The typical hardness of the films was approximately 26.24-30.37 GPa.     

Characterization of Sn-doped BST thin films on LaNiO<Subscript>3</Subscript>–coated Si substrate

Sn-doped (Ba,Sr)TiO₃(BSTS) thin films have been deposited on highly (200) oriented LaNiO₃(LNO) thin films by sol-gel method. The atomic force microscope (AFM) images exhibited that the dopant Sn did not decrease the crystalline grain size of BST thin films. The structure of the BST film, determined by X-ray diffraction (XRD), presented the higher intensity (110) and (200) peaks, while the latter was distinctly induced by LNO layer. Evidently, Sn-doped BST thin films on LNO/Si substrate were found to decrease the dielectric constant and the dielectric loss, which is favourable to potentially improve the figures of merits (F _D ) of pyroelectric materials. The BSTS thin films on LNO layer also displayed an excellent leakage current property comparing with the BST thin film on Pt/Ti/SiO₂/Si and LNO/Si substrates.     

中频孪生靶非平衡磁控溅射制备氮化硅薄膜及其性能(英文)

本文采用中频孪生靶非平衡磁控溅射技术在不同氮气流量比例的条件下制备出氮化硅薄膜。利用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、原子力显微镜(AFM)、椭偏仪等研究了氮气流量比率对氮化硅薄膜的微观结构、表面形貌、沉积速率、折射率的影响。结果表明:中频孪生非平衡磁控溅射技术制备的薄膜为非晶态氮化硅。随着氮气流量比率的增加,Si-N键红外光谱吸收带向低波数漂移,薄膜的沉积速率降低,表面结构更为光滑致密,氮化硅薄膜的折射率降低。薄膜的硬度和杨氏模量分别达到22和220GPa左右。     

Zinc phthalocyanine — Influence of substrate temperature, film thickness, and kind of substrate on the morphology

Zinc phthalocyanine (ZnPc), C₃₂H₁₆N₈Zn, is a planar organic molecule having numerous optical and electrical applications in organic electronics. This work investigates the influence of various deposition parameters on the morphology of vapour thermal evaporated ZnPc films. For this purpose, ZnPc is deposited at different substrate temperatures up to 90 °C and film thickness up to 50 nm onto various substrates. The morphology of this ZnPc layers is characterised by X-ray diffraction (XRD), X-ray reflectivity (XRR) and atomic force microscopy (AFM) methods. XRD measurements show that all ZnPc films are crystalline in a triclinic (α-ZnPc) or monoclinic (γ-ZnPc) phase, independent from the kind of substrate, layer thickness, or substrate temperature. The ZnPc powder, the starting product for the thermally evaporated ZnPc films, is present in the stable monoclinic β-phase. Thus, the stacking of the ZnPc molecules changes completely during deposition. The crystallite size perpendicular to the substrate determined by XRD microstructure analysis is in the range of the layer thickness while the lateral size, obtained by AFM, is increasing with substrate temperature and film thickness. AFM and XRR show an increase of the layer roughness for thicker ZnPc layers and higher substrate temperatures during film deposition. The strain in the ZnPc films decreases for higher substrate temperatures due to enhanced thermal relaxation and for thicker ZnPc films due to lower surface tension.     

Growth of pseudocubic perovskite-type SrRuO3 thin films on quartz substrate using pulsed laser deposition method

Strontium ruthenium oxide (SrRuO₃) thin films have been grown using pulsed laser deposition technique on silicon, Pt coated silicon and quartz substrates. The effect of substrate temperatures on the structural, microstructure, and electrical properties of the SrRuO₃ films on quartz substrate has been investigated using XRD, SEM, AFM and four-probe method, respectively. The lowest resistivity at room temperature for the SrRuO₃ thin film on quartz substrate has been achieved at substrate temperature of 700 °C. Furthermore, the comparisons of SrRuO₃ thin films deposited on various substrates have been done with respect to structural, microstructural and electrical properties. XRD patterns exhibit that all thin films are a single phase, pseudo-cubic perovskite structure. Study of surface morphology shows that grain size and roughness varies with respect to substrate. It is observed that SrRuO₃ thin films yield larger grain size and root mean square roughness on Pt/Si substrate. Investigation of electrical properties shows that SrRuO₃ thin films can serve the purpose of the bottom electrode in dielectric and ferroelectric devices.     

Characterization of reactively sputtered c-axis orientation (Al, B)N films on diamond

In this research, we demonstrated the viability of oriented AlN layer that incorporated BN to enhance the texturing. Wurtzite (Al, B)N films were deposited on a diamond wafer (diamond film on Si wafer) by a co-sputtering technique. The preferred orientation structure is sensitive to sputtering control factors. The relationship between the microstructures and process conditions were examined with XRD, TEM and AFM analysis. The cross-section TEM images showed that amorphous and randomly aligned structures were produced in the initial sputtering period, but the higher c-axis orientation structure formed as the sputtering time increased. The thickness of the amorphous and randomly aligned layer decreased with increasing sputtering power, nitrogen concentration, substrate temperature and bias voltage. As the thickness of the amorphous and the randomly aligned layer decreased, an (Al,B)N film with higher film quality than AlN was observed.     

Si(111)衬底上生长GaN晶绳的研究

利用热壁化学气相沉积在Si(111)衬底上获得GaN品绳，采用傅里叶红外吸收谱(FTIR)、扫描电子显微镜(SEM)、选区电子衍射(SAED)、X射线衍射(XRD)和光致发光谱(PL)对晶绳进行组成、结构、形貌和光学特性分析。初步结果证明：在Si(111)衬底上获得择优生长的六方纤锌矿结构的GaN晶绳。SEM显示在均匀的薄膜上出现φ6μm的晶绳，FTIR显示GaN薄膜的主要成分为GaN同时含有少量的C污染，由XRD和SAED的综合分析得出晶绳呈六方纤锌矿单晶结构，PL测试表明晶绳呈现不同于GaN薄膜的发光特性。     

Integration of stacked capacitor module with ultra-thin ferroelectric SrBi2Ta2O9 film for high density ferroelectric random access memory applications at low voltage operation

The crystallization route of thin SrBi₂Ta₂O₉ (SBT) films deposited on Pt(100 nm)/Ti(10 nm)/SiO₂/Si substrate is investigated at different annealing temperatures by atomic force microscopy (AFM) and X-ray diffractometry (XRD). To evaluate the SBT film properties for low voltage operation and for high storage density (>16 MBit), SBT is deposited at different film thicknesses. Furthermore, the performance of a Pt/SBT/Pt capacitor on a barrier-/contact-layer/polysilicon-plug architecture suitable for stacked capacitor memories is investigated by transmission electron microscopy (TEM)/energy dispersive X-ray analysis (EDX) and electrical measurements. It is shown that an oxidized and highly resistive contact layer can be recovered by electrical pulses. Finally, a process solution for a successful integration of 38 nm thin SBT films into this structure is provided.     

Effects of buffer layer thickness on properties of ZnO thin films grown on porous silicon by plasma-assisted molecular beam epitaxy

ZnO thin films with different buffer layer thicknesses were grown on Si and porous silicon (PS) by plasma-assisted molecular beam epitaxy (PA-MBE). The effects of PS and buffer layer thickness on the structural and optical properties of ZnO thin films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL). The ZnO buffer layers, the intensity of the (002) diffraction peak for the ZnO thin films and its full width at half maximum (FWHM) decreased with an increase in the thickness of the ZnO buffer layers, indicating an improvement in the crystal quality of the films. On introducing PS as a substrate, the grain sizes of the ZnO thin films became larger and their residual stress could be relaxed compared with the ZnO thin films grown on Si. The intensity ratio of the ultraviolet (UV) to visible emission peak in the PL spectra of the ZnO thin films increased with an increase in buffer layer thickness. Stronger and narrower UV emission peaks were observed for ZnO thin films grown on PS. Their structural and optical properties were enhanced by increasing the buffer layer thickness. In addition, introduction of PS as a substrate enhanced the structural and optical properties of the ZnO thin films and also suppressed Fabry-Perot interference.     

SiO2层上沉积的纳米多晶硅薄膜及其特性

采用低压化学气相沉积(LPCVD)系统以高纯SiH4为气源,在p型10.16 cm<100>晶向单晶硅衬底SiO2层上制备纳米多晶硅薄膜,薄膜沉积温度为620℃,沉积薄膜厚度分别为30 nm、63 nm和98 nm.对不同薄膜厚度的纳米多晶硅薄膜分别在700℃、800℃和900℃下进行高温真空退火.通过X射线衍射(XRD)、Raman光谱、扫描电子显微镜(SEM)和原子力显微镜(AFM)对SiO2层上沉积的纳米多晶硅薄膜进行特性测试和表征,随着薄膜厚度的增加,沉积态薄膜结晶显著增强,择优取向为<111>晶向.通过HP4145B型半导体参数分析仪对沉积态掺硼纳米多晶硅薄膜电阻I-V特性测试发现,随着薄膜厚度的增加,薄膜电阻率减小,载流子迁移率增大.     

通过制备Ti/TiC和Si/SixNy过渡层在铜基体上沉积类金刚石膜的研究

将磁控溅射物理气相沉积（MS-PVD）和电子回旋共振-微波等离子体增强化学气相沉积（ECR—PECVD）技术相结合，在铜基体上通过制备两种不同的过渡层，成功地沉积了类金刚石膜。拉曼光谱结果分析表明，所制备的碳膜都具有典型的类金刚石结构特征。通过原子力显微镜对薄膜的微观形貌进行分析，采用纳米压痕测量薄膜的硬度和模量。并对Ti／TiC过渡层和Si／SixNy过渡层上沉积的类金刚石薄膜进行了研究对比。     

溅射功率对AZO透明导电薄膜的影响

采用射频磁控溅射法在玻璃衬底上沉积了AZO透明导电薄膜,并用原子力显微镜观测了薄膜表面形貌,XRD测试了薄膜相结构和单色仪测试了薄膜透射率。结果表明,制备的薄膜具有高度c轴择优取向性,其表面平整,晶粒均匀致密。当溅射功率为180W、溅射气体流量为15sccm、基片温度为200℃时制得的薄膜方阻为10Ω/□,在可见光区平均透射率大于85%。