Density behaviors of Ge nanodots self-assembled by ion beam sputtering deposition

Self-assembled Ge nanodots with areal number density up to 2.33× 1010 cm-2 and aspect ratio larger than 0.12 are prepared by ion beam sputtering deposition. The dot density, a function of deposition rate and Ge coverage, is observed to be limited mainly by the transformation from two-dimensional precursors to three-dimensional islands, and to be associated with the adatom behaviors of attachment and detachment from the islands. An unusual increasing temperature dependence of nanodot density is also revealed when a high ion energy is employed in sputtering deposition, and is shown to be related to the breaking down of the superstrained wetting layer. This result is attributed to the interaction between energetic atoms and the growth surface, which mediates the island nucleation.

Nano-sized Thin Films Fabricated by Ion Beam Sputtering and Its Properties

Nanoscale thick amorphous Ni-Cr alloy thin films were fabricated by low-energy ion beam sputtering technology; then the as-deposited samples experienced rapid thermal process to realize the transformation from amorphous to crystalline state. The film thickness was measured with a-stylus surface profiler, the structure and the compositions of the films were confirmed by low angle X-ray diffraction and scanning auger electron microprobe respectively, and the surface topography was characterized by scanning electron microscope and scanning probe microscope. Electrical property of the films was measured by fourpoint probe. The experimental results illustrate that the combined processes of ion beam sputtering and rajid thermal process are effective for fabrication nanoscale Ni-Cr alloy thin film with good properties.

Preparation of YBa_2Cu_3O_(7-x) Superconductor Film by Ion Beam Sputtering

Since the discovery of high T;super-conductor, much effort was made toits application. More and more evidencehas revealed that most promising fieldof high T;superconductor first to havesuccess must be the microelectronics andcomputer. Superconductor films for mi-croelectronic application are preparedby PVD method, such as electron beamevaporation, pulsed laser evaporation andmagnetron sputtering. In this paper, thepreliminary results of ion beam sputteringdeposition of YBaCuO film are reported

Structure and Magnetic Properties of Fe-N Films Prepared by Dual Ion Beam Sputtering

Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).

Interfacial Electronic Structure of Thin Cu Films Grown on Ar^+-ion Sputter-cleaned α-Al_2O_3 Substrates

The bonding and electronic structure of Cu/(0001)Al2O3 and Cu/(1120)Al2O3 interfaces has been studied experimentally using spatially-resolved transmission electron energy loss spectroscopy. The specimen were prepared by depositing Cu on single-crystal α-AI2O3 substrates, which have been Ar+-ion sputter-cleaned prior to the growth of Cu. For both orientations of the α-Al2O3 substrate, atomically abrupt interfaces formed as determined by high-resolution transmission electron microscopy. The investigations of the interfacial Cu-L2,3, Al-L2,3 and 0-K energy loss near-edge structures, which are proportional to the site- and angular-momentum-projected unoccupied density of states above the Fermi level, indicate the existence of metallic Cu-AI bonds at the Cu/AI2O3 interface independent of the substrate orientation.

Studies on Ion-Beam Modified Hydrogen Evolution Electrodes

he present paper focuses on the modifying effects of ion beam mixing, ion im-planting and ion sputtering on hydrogen evolution electrodes. It was discovered thatthe four types of electrodes possessed excellent catalytic activity in acid or alkalinemedia and potential stability in long term electrolysis of water under high currentdensity. Their stability and applying life-span greatly surpass those of other elec-trodes activated by electrodepositing and other method. The effects of temperatureand roughness on function of electrodes were also examined. XPS and AES wereapplied to analyse the surface composition and bond states of the electrodes, andthe distribution of concentration varying with depth, and to explain the law of theexperiments .

Infrared transition properties of vanadium dioxide thin films across semiconductor-metal transition

Vanadium dioxide thin films were fabricated through annealing vanadium oxide thin films deposited by dual ion beam sputtering. X-ray diffraction （XRD）, atom force microscopy （AFM）, and Fourier transform infrared spectrum （FTIR） were employed to measure the crystalline structure, surface morphology, and infrared optical transmittance. The phase transition properties were characterized by transmittance. The results show that the annealed vanadium oxide thin film is composed of monoclinic VO2, with preferred orientation of （011）. The maximum of transmittance change is beyond 65% as the temperature increases from 20 to 80 C. The reversible changes in optical transmittance against temperature were observed. The change rate of transmittance at short wavelength is higher than that at long wavelength at the same temperature across semiconductor-metal phase transition. This phenomenon was discussed using diffraction effect.

Synthesis,Characterization and Photoluminescence of Well-Ordered ZnO Micropillars Grown on ZnO Buffer Layers

Using ZnO buffer layers prepared by simply thermal oxidation of ion beam sputtered Zn films, highly oriented and uniformly aligned single-crystalline ZnO micropillars arrays have been synthesized by thermal evaporation of Zn powder with flee catalysts at low temperature of 430℃ The ZnO micropillars show sharp hexagonal umbrella-like tips with thin ZnO nanowire grown on the tips. The umbrella-like tips grow in a layer-by-layer mode along the direction of [001]. The growth mechanism has been discussed. The formation of the micropillars basically depends on the gradually decreasing Zn vapor pressure and subsequently cooling process. The photoluminescence （PL） spectrum indicates a moderately good crystal quality of the ZnO micropillars. Our results may reinforce the understanding of the formation mechanism of different ZnO nano/microstructures. This kind of complex microstructures may find potential applications in multifunctional microdevices, optoelectronic and field emission devices.

Recent Developments in Magnetron Sputtering

The principle of magnetron sputtering is introduced andthe balanced and unbalanced magnetrons are compared andthe necessity of unbalanced magnetrons is explained as well. Several recent developments in plasma magnetron sputtering, i.e., unbalanced magnetron sputtering, pulsed magnetron sputtering and ion assisted sputtering, are discussed. The recent developments of unbalanced magnetron systems and their incorporation with ion sources result in an understanding in growingimportance of the magnetron sputtering technology, which makes the technology an applicable deposition process for a variety of important films, such as wear-resistant films and decorative films.

Characterization of Ti-Cu Films Deposited by HPPMS and Effect on NO Catalytic Release and Platelet Adhesion Behavior

Ti-Cu films with different Cu concentrations were fabricated by high-power pulsed magnetron sputtering（HPPMS） to release copper ions and catalyze NO to improve the blood compatibility. The Cu concentrations of films were 25.7 at% and 68.8 at%. Pure Ti films were also fabricated. Copper release, catalytic release of nitric oxide（NO）, and blood platelet adhesion of Ti-Cu films were studied. Ti-Cu films released copper ions in PBS solution and more Cu ions were released from films with 68.8 at% Cu. Ti-Cu films had excellent ability of catalytical decomposition of exogenous donor S-nitroso-N-acetyl-DL-penicillamine（SNAP） and as a result, nitric oxide（NO） was generated. The NO generation catalyzed by Ti-Cu films was significantly higher than that by pure Ti films. This was more eminent in the Ti-Cu films with 68.8 at% Cu. The platelet adhesion and activation of Ti-Cu films were significantly inhibited compared to that of pure Ti films in the presence of SNAP. The Ti-Cu film fabricated by HPPMS showed the ability of releasing Cu ions to catalyze SNAP to generate NO to inhibit platelet adhesion and activation.

Enhanced ultraviolet photoresponse based on ZnO nanocrystals/Pt bilayer nanostructure

The development of solution strategies for Zinc oxide （ZnO） quantum dots provides a pathway to utilizing ZnO nanocrystal thin films in optoelectronic devices. In this work, quasi-spherical ZnO quantum dots with a diameter of 5 nm are synthesized by using ethanol as a solvent. ZnO nanocrystal thin film is obtained by spin-coating ZnO quantum dots on a Au interdigital electrode （IDE）/AI203 substrate and annealing at different temperatures in order to yield the optimal pho- tosensitive on/off ratio of ZnO. For further enhancing the responsivity, ion sputtering is utilized to deposit Pt nanoparticles on the surface of ZnO nanocrystal thin film, the responsivity of the ZnO/Pt bilayer nanostructure increases from 0.07 A/W to 54 A/W, showing that the metal/inorganic nanocrystal bilayer nanostructure can be used to improve the performance of optoelectronic devices. The excellent properties of ZnO/Pt bilayer nanostructure have important applications in future electronic and optoelectronic devices.

Influence of Negative Bias Voltage on the Mechanical and Tribological Properties of MoS_2/Zr Composite Films

MoS2/Zr composite films were deposited on the cemented carbide YT14 （WC＋14%TiC＋6%Co） by medium-frequency magnetron sputtered and coupled with multi-arc ion plated techniques.The influence of negative bias voltage on the composite film properties,including adhesion strength,micro-hardness,thickness and tribological properties were investigated.The results showed that proper negative bias voltage could significantly improve the mechanical and tribological properties of composite films.The effects of negative bias voltage on film properties were also put forward.The optimal negative bias voltage was -200 V under this experiment conditions.The obtained composite films were dense,the adhesion strength was about 60 N,the thickness was about 2.4 μm,and the micro-hardness was about 9.0 GPa.The friction coefficient and wear rate was 0.12 and 2.1×10-7 cm3/N·m respectively after 60 m sliding operation against hardened steel under a load of 20 N and a sliding speed of 200 rev·min-1.

Gas-sensing Properties of Bismuth Iron Molybdate Thin Films

The thin film gas sensors of bismuth iron molybdate were prepared by ion beam sputtering technique. The prototype gas sensors studied have high sensitivity and selectivity to reducing gases, such as ethanol vapor, show a long term stability of response under most operating conditions and insensitivity to atmospheric humidity, and respond quickly comparing to traditional sintered gas sensors. The crystallographic structure and phase composition of these thin films were investigated with XRD, XPS and SEM techniques.

Spatial separation effects in a guiding procedure in a modified ion-beam-sputtering process

In the present state of the art,ion beam sputtering is used to produce low-loss dielectric optics.During the manufacturing of a dielectric layer stack,the deposition material must be changed,which requires rapid mechanical movement of vacuum components.These mechanical components can be regarded as a risk factor for contamination during the coating process,which limits the quality of high-end laser components.To minimize the particle contamination,we present a novel deposition concept that does not require movable components to change the coating material during the coating process.A magnetic field guiding technique has been developed,which enables the tuning of the refractive index in the layer structure by sputtering mixtures with varying compositions of two materials using a single-ion source.The versatility of this new concept is demonstrated for a highreflection mirror.