Bingyao Jiang

Short-wavelength photoluminescence from silicon and nitrogen coimplanted SiO2 films

Intense short-wavelength photoluminescence (PL) observed at room temperature from thermal SiO2 films implanted with Si and N is reported. A flat Si profile was first created. N ions were subsequently implanted into the same depth region as the implanted Si ions. Two PL bands peaking at ∼330 and ∼430 nm were observed from the samples at room temperature with and without annealing. It is found that the PL has a strong dependence on the stabilized N in the Si- and N-coimplanted SiO2 films. The PL may originate from a complex of Si, N, and O.

Electron emission suppression characteristics of molybdenum grids coated with carbon film by ion beam assisted deposition

Carbon was coated on the surface of molybdenum grids by ion beam assisted deposition. The electron emission characteristics from the grids with and without carbon, which were contaminated by an active electron emission substance of the cathode, was measured using an analogous diode method. The results show that electron emission from the carbon-coated Mo grid was much less than that from the Mo grid without carbon. The cathode emission substance deposited on the carbon surface of the grid was analyzed by x-ray photoelectron spectroscopy and electron probes. Analysis results revealed that the carbon-coated Mo grid could effectively reduce the accumulation of the cathode emitting substances Ba and BaO on the grid surface. The reason for the suppression of electron emission of the carbon-coated Mo grid is discussed. The carbon-coated Mo grids were used in pulsed-controlled grid traveling wave tubes and the working lifetime of the tube was increased from tens of hours to over 1000 h.

Alumina, aluminium nitride and aluminium composite coating on 0.45% C steel by using a plasma source ion implantation and deposition (PSII&D) system

Abstract Al 2 O 3 , AlN and Al composite coating was synthesized on 0.45% C steel sample to improve its corrosion resistance ability by using a plasma source ion implantation and deposition (PSII&D) system. The PSII&D is an extension of PSII by the combination of steady-state gas plasma and pulsed metal plasma. The gas plasma is produced by magnetic multipole filament discharge (or glow discharge) and the metal plasma is produced by pulsed cathodic arc discharge. The electrochemical corrosion test of the coating shows that the corrosion resistance ability of the coated 0.45% C steel sample was greatly improved. The microstructure, surface compositions, depth profile, bonding environment and morphology of the coating were investigated by X-ray diffraction (XRD), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The results show that the coating is formed by Al 2 O 3 , AlN and Al. The improvement in corrosion resistance ability of 0.45% C steel is due to the formation of the composite coating.

Different luminescent properties of C+-implanted SiO2 films grown by thermal oxidation and PECVD

Abstract Room temperature photoluminescence (PL) from C+-implanted SiO2 films grown by thermal oxidation and PECVD is reported. There are great differences in the luminescent properties, which are shown by PL spectra, PL excitation (PLE) spectra, and the PL dynamics. The structural analysis of the C+-implanted SiO2 films are taken by FTIR, Raman, and HRTEM. The differences in light emission are attributed to the structural characteristics of SiO2 films before and after C ion implantation.

Photoluminescence properties of thermal SiO2 films implanted by silicon and nitrogen ions

Intense UV–visible photoluminescence (PL) was observed at room temperature from thermal SiO2 films implanted by Si and N ions. There were two PL bands at ∼330 and ∼660 nm shown in the as-implanted sample, while another band at ∼430 nm was observed apart from the other two bands. No shifts were observed in the PL spectra with increasing annealing temperature. The annealing temperature dependences of N distribution, PL intensity and electron spin resonance (ESR) signals were also measured. It is found that the PL is related to the N in the films. The PL is suggested to originate from complex of Si, N and O.

Light-emitting materials fabricated by dual implantation of Si and N into SiO2 films

Abstract A new method to fabricate Si-based, light-emitting materials by dual ion implantation of Si and N into SiO2 films is reported. The Si and N ions were respectively used with three different energies at corresponding doses. As revealed by secondary ion mass spectroscopy (SIMS) depth profile, the implanted N ions have a uniform distribution in a wide region under the surface. Infrared reflection spectra indicate that the microstructures of the films are stable even after annealed at 600°C. Intense UV–visible photoluminescence (PL) peaking at ∼330, ∼430, and ∼660 nm, respectively, was observed at room temperature from the as-implanted samples with or without annealing. The PL peak intensities vary with the annealing temperature, and have a maximum at about 600°C. The electron spin resonance (ESR) signals decrease monotonically with the increment of the annealing temperature and disappear when the annealing temperature is higher than 600°C. The PL is attributed to some defects or N-bonded Si–O species.

Anti-emission characteristics of the grid coated with hafnium film

Hf was deposited onto the surface of Mo grids by ion-beam-assisted deposition. The electron-emission characteristics of the grids with and without Hf, which were contaminated by active electron-emission substances (Ba, BaO) of the cathode, were measured using an analogous-diode method. The surfaces of the grids were analyzed by x-ray diffraction and x-ray photoelectron spectroscopy. The results showed that electron-emission current from the Mo grid coated with Hf film was less than that from the Mo grid without Hf. During the course of the testing, active electron-emission substances from the cathode were deposited continuously onto the surface of the grid. Due to BaHfO3 compounds and Ba-Hf diffusion, the Mo grid coated with Hf effectively reduced the electron-emission substances on the grid from the cathode, which reduced grid electron emission.

Control of the YSZ biaxial alignment on polycrystalline NiCr substrates by ion beam selective resputtering

(001)-oriented and in-plane aligned yttria-stabilized zirconia (YSZ) films were synthesized on polycrystalline NiCr substrates by ion beam assisted deposition (IBAD). The YSZ biaxial alignment were found to be controlled by the assisted argon ion beam bombardment. The incident angle and energy of the assisted bombarding ion beam strongly influence the alignment. The optimal alignment was obtained with the assisted ion beam bombarding at 55° incident angle and 250–500 energy. The Monte Carlo method was used to simulate the alignment formation with argon ions bombarding the zirconia crystals. Results indicated that when the energy of the bombarding ions is less than 50 eV, there is no obvious difference in the sputtering yields and the radiation damage of zirconia between different incident angles. However with the ion energy increasing, the variation increases rapidly. When the ion energy reaches 250 eV, the sputtering yields and the radiation damage of zirconia induced by Ar+ bombarding along [111] direction (54.7° from the [001]) of the zirconia are much lower than those produced by Ar+ bombarding along other directions. It can be concluded that the (001)-oriented grains are resputtered less than other grains when the assisted ions bombarding at 55° incident angle, which causes YSZ grains with (001) orientation to prevail over initial random oriented grains and form the biaxial alignment.

Growth of Biaxially Textured Yttria-Stabilized Zirconia Thin Films on Si(111) Substrate by Ion Beam Assisted Deposition

The (001) oriented yttria-stabilized zirconia (YSZ) films with in-plane biaxial texture have been deposited on Si(111) substrates by ion beam assisted deposition at ambient temperature. The effects of ion/atom arrival rate ratio (R=(Ar++O2+)/ZrO2) and incident angle of bombarding ion beam on the film texture development were investigated. It was found that the in-plane biaxial texture of the films was improved gradually with increasing ion/atom arrival rate ratio R up to a critical value 1.9, but it was degraded with the further increase of R. The optimal in-plane biaxial texture, whose full width at half maximum of the (111) -scan spectrum is 14°, can be obtained at R=1.9 and incident angle of 55°. For a fixed R, the optimal crystallinity and in-plane biaxial alignment of the YSZ films did not appear at the same incident angle and showed an opposite variation with the change of the incident angle from 51° to 55°. C-axis alignment (perpendicular to substrate surface) does not show any substantial variation with the change of incident angle within the range of 47° - 56°.

Ion beam modification of intermetallic compounds Ni3Al(0.1B) and TiAl

Abstract The corrosion and oxidation behaviour of intermetallic compounds Ni 3 Al(0.1B) and TiAl treated with different ion beam techniques was systematically investigated. The results revealed that ion implantation, ion beam mixing and ion beam enhanced deposition are very effective for improving the corrosion resistance in aqueous solution and the protective properties against high temperature oxidation of intermetallic compounds.