SrBi2Ta2O9(SBT) films were prepared by metalorganic decomposition technique. The films were obtained by spin-on pyrolysis of the precursor solutions on various substrates and then annealed at 550-850°C in dry oxygen, wet oxygen, or Ar. Effects of precursor solution concentration, anneal temperature, anneal atmosphere, substrate and Ar ion sputtering on the microstructure, morphology and electrical properties were investigated by means of x-ray diffraction, scanning electron microscope, atomic force microscope, x-ray photoelectron spectroscopy, and electrical measurements. The results indicated the grain size, and the remnant polarization (Pr) increased with increasing the anneal temperature up to 800°C and the significant hysteresis loop could be obtained only after anneal above 700°C. At 850°C, the pyrochlore phase and other secondary phases were observed along with the SBT phase, leading to the decreasing Pr and dielectric constant. In addition, the development of crystalline phase and electrical properties were affected by anneal atmosphere. When annealed in Ar at 750°C, the layered SBT structure was destroyed with evident Bi loss. As though the original structure could be restored basically by subsequent adequate O2 anneal, the electrical properties were deteriorated seriously due to the shorted capacitor. Wet oxygen anneal evidently deformed the morphology and the hysteresis loop. This was attributed to the effect of possible produced slight H2 due to the reaction between H2O and residual carbonaceous in films under Pt catalyst. Substrates also played an important role on film crystallinity. The films deposited on Si, SrTiO3, and crystal quartz at 750°C had a layered perovskite polycrystalline structure while the films on fused quartz exhibited poor crystalline nature even after 800°C anneal and films on NaCl showed (200)-predominant orientation of SBT phase with some pyrochlore. In addition, Ar ion sputtering might lead to the severe Bi and oxygen deficiency in the surface of the sputtered film. © 2000 American Institute of Physics.

Li Aidong;Wu Di;Ling Huiqin;Yu Tao;Wang Mu;Yin Xiaobo;Liu Zhiguo;Ming Naiben

Journal of Applied Physics

2000

One excimer laser pulse through a silicon glass phase mask was used to directly generate periodic surface structures on top of a lithium niobate (LN) wafer. The surface corrugations have a period that is the same as that of the mask grating. Measurement of the grating coupler with a He-Ne laser beam coupling into the waveguide found three mode of incident lights transmitting into the waveguide.

Luo Gui peng;Wang Mu;Zhu Shi ning;Liu Zhi guo;Lu Yan qing;Chen Xiao yuan;Ge Chuan zhe;Ming Nai ben;Wu Hai ming;Lu Zhu hong

Pacific Rim Conference on Lasers and Electro Optics CLEO Technical Digest

1997

Oriented LiNbO 3 thin films have been prepared by pulsed laser deposition on fused silica substrates under a proper low electric field. The as-grown films were characterized by means of X-ray diffraction θ-2θ scans, X-ray photo-electron spectrometry and atomic force microscopy. Significant effects of the substrate temperature and magnitude of the applied electric field on the orientation of the films are revealed, demonstrating the preferred electric field of ∼7 V/cm and substrate temperature of 600°C. Drastic influence of the substrate temperature on the stoichiometry of the thin films is also shown. The as-prepared thin films show quite good surface quality. © 1998 Elsevier Science B.V.

Wu Z. C.;Hu W. S.;Liu J. M.;Wang M.;Liu Z. G.

Materials Letters

1998

A series of Co 35 (SiO 2 ) 65 (volume fraction) nano-granular films with different annealing temperature (T A ) were fabricated using ion-beam sputtering technique. A giant magnetoresistance of about 4% at room temperature was observed. The transmission electronic microscopy (TEM) observation shows clearly isolated nano-scale cobalt particles embedded in the SiO 2 matrix. A magnetic force microscopy (MFM) was used to image the topography and magnetic microstructures of Co 35 (SiO 2 ) 65 nano-granular film. The domains were resolved clearly on MFM micrographs with much larger size (about 10-20 nm) than that of cobalt particles (about 1-2 nm) in the annealed samples, which demonstrated that there may be interparticle correlation among many of the isolated single-domain cobalt particles.

Xu Q. Y.;Chen H.;Sang H.;Yin X. B.;Ni G.;Lu J.;Wang M.;Du Y. W.

Journal of Magnetism and Magnetic Materials

1999

Combined with atomic force microscope (AFM), micro-Raman spectroscope, cross-section transmission electron microscope (TEM) and high resolution electron microscope (HREM) analyses, the surface morphology and structures of a-Si:H/a-SiN x :H multilayers (MLs), irradiated by excimer laser through the phase shifting mask grating, are investigated. It is found that Si nanocrystallites (nc-Si) are formed within the initial a-Si:H sublayers, and the size of the grains can be controlled due to the constrained crystallization effect. And it is possible to use this laser interference crystallization (LIC) method to get the periodic distribution of nc-Si in both transverse and longitudinal direction.

Wang Li;Li Jian;Huang Xinfan;Li Qiliang;Yin Xiaobo;Fan Wenbin;Xu Jun;Li Wei;Zhu Jianming;Wang Mu;Liu Zhiguo;Chen Kunji;Li Zhifeng

Applied Surface Science

2000

(Ba0.5Sr0.5)TiO3 (BST) thin films were deposited on Si and plantinized Si substrates using sol-gel method with rapid thermal annealing (RTA). The films were characterized by inductive coupled plasma (ICP) analysis, X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and electrical measurements. BST get well crystallized after RTA at 700 °C for 5 min. Grain size, grain height, and thus, surface roughness and film density increase with the increase of annealing time. SEM cross-section results clearly demonstrate a better BST/substrate interface compared with conventional annealing. The dielectric constant and loss tangent of BST films at 10 kHz are 435 and 0.069, respectively. This good dielectric property is believed to arise from the better BST/substrate interface.

Wu Di;Li Aidong;Ling Huiqin;Yin Xiaobo;Ge Chuanzhen;Wang Mu;Ming Naiben

Applied Surface Science

2000

Strontium bismuth tantalate Sr1-xBi2.2Ta2O9 (SBT, x = 0, 0.1, 0.2, 0.3, 0.4, 0.6) thin films with deficient Sr contents were prepared at 750 °C on Pt/TiO2/SiO2/Si substrates using metalorganic decomposition (MOD) spin-on technique. Effect of Sr deficiency compositions on the structural and electrical properties were investigated by means of X-ray diffraction (XRD), inductively coupled plasma (ICP) analyses, electronic probe microanalyses (EPMA), atomic force microscope (AFM), scanning electron microscope (SEM) and electrical measurements. The XRD results indicate the films with Sr deficiency content at 40% and below have layered perovskite structure with the distorted lattice. For films with 60% deficient Sr, the layered structure cannot be formed. SEM and AFM micrograph shows the surface morphology is very sensitive to the Sr deficiency. With increasing the Sr deficiency to 40% and above, the films exhibit the extremely inhomogeneity and poor crystallinity. The remnant polarization (Pr) gradually reduces with Sr deficiency. This is attributed to the distorted layered structure and the formation of amorphous phase. In summary, SrBi2.2Ta2O9 is found to be the optimum composition with respect to grain size, morphology, and electrical properties.

Li Aidong;Ling Huiqin;Wu Di;Yu Tao;Wang Mu;Yin Xiaobo;Liu Zhiguo;Ming Naiben

Applied Surface Science

2001

The SrBi2Ta2O9 (SBT) thin films were prepared on Pt/TiO2/SiO2/Si substrates by metalorganic decomposition method. The films were annealed layer by layer at 650-800°C for 3 minutes in oxygen using rapid thermal annealing. The structure, morphology and electrical properties of as-deposited films were characterized using X-ray diffraction, atomic force microscope, Auger electron spectroscopy and some electrical measurement. The films showed smaller grains, higher density, less interfacial diffusion and smaller remnant polarization than those annealed in conventional tube furnace. The remnant polarization and coercive field at applied voltage of 3 V were 8.7μC/cm² and 13.4kV/cm, respectively, for the 440nm-thick films annealed at 750°C. The coercive field was much lower than those reported previously. This is advantageous to low voltage applications in nonvolatile memory. The films also exhibited no fatigue after 10¹⁰ cycles switching and no loss after 10⁵s retention time.

Ling Huiqin;Li Aidong;Wu Di;Yu Tao;Zhu Xinhua;Yin Xiaobo;Wang Mu;Liu Zhiguo;Ming Naiben

Integrated Ferroelectrics

2001

Rutile titanium dioxide films with preferred orientation were grown on semiconducting gallium arsenide substrates via pulsed laser deposition. The films were deposited at 700 degrees celsius under base vacuum. The films exhibited epitaxial properties. The surface morphology were observed using atomic force microscopy.

Liu X.;Chen X. Y.;Yin J.;Liu Z. G.;Liu J. M.;Yin X. B.;Chen G. X.;Wang M.

Journal of Vacuum Science and Technology Part A Vacuum Surfaces and Films

2001

Nd6Dy2Fe82Co4B6 ribbons, prepared by melt spinning, have been investigated by X-ray diffraction (XRD), thermomagnetic analysis (TMA), vibrating sample magnetometer (VSM) and magnetic force microscopy (MFM). XRD and TMA show that the ribbons consist of the α-Fe phase and the Nd9Fe14B phase. A high remanence ratio of 0.65 and a relatively high coercivity of 4.9 kOe were achieved in the optimal ribbons. The remanence enhancement is attributed to the exchange coupling between the magnetically hard and the magnetically soft phases. Comparing the MFM image of the optimal ribbon with that of the exchange-decoupled ribbon, we found that the mean magnetic domain size of the optimal ribbon is larger than that of the exchange-decoupled ribbon, which can be attributed to the stronger exchange interaction between grains in the optimal ribbons.

Yin Jin-Hua;Shen Bao-Gen;Wang Dun-Hui;Yin Xiao-Bo;Wang Mu;Du You-Wei

Journal of Alloys and Compounds

2001