Si-Ze Yang

Materials science communication formation of aln films by al evaporation with nitrogen ion beam bombardment

Abstract Aluminum nitride films were synthesized by electron gun evaporation of aluminum on to Si (111) wafer with simultaneous bombardment by nitrogen ions. Under special conditions, polycrystalline AlN films of fine crystallinity were obtained.

A new method for inner surface modification by plasma source ion implantation (PSII)

Abstract A new method for inner surface modification, named grid-enhanced inner surface modification by plasma source ion implantation (PSII), was proposed and demonstrated in this paper. By introducing an RF plasma core, which is produced between a central cathode and a coaxial grid electrode, and sputtering the cathode, uniform ion implantation and film deposition on the inner surface of a tubular sample can be realized based upon the PSII technique.

Pulsed high energy density plasma processing silicon surface

Pulsed high energy density plasma (PHEDP) is a new material modification technique, which has the features of: high energy density (1–10 J/cm2), high plasma density (1014–1016 cm−3), high electron temperature (10–100 eV), high directed plasma velocity (10–100 km/s) and short pulse duration (10–100 μs). PHEDP interacting with material will result in rapid melting and re-solidification of surface layer with a quenching rate up to 108 K/s; thus the material surface properties are modified. At the same time, PHEDP contains condensable ions or/and atoms, so a thin film layer can be formed on the modified surface and the deposited layer can be mixed with the substrate (or previous deposited layer) during following pulses. Therefore, this technique actually combines film deposition and mixing into one step. In this paper, we have reported the research results on the metallization of Si by PHEDP. The Tiue5f8Si reactions under PHEDP are also discussed.

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.

Investigation of the interface reactions of Ti thin films with AlN substrate

Pure bulk AIN substrates were prepared by hot-pressing to eliminate the influence of an aid-sintering substance on the interface reactions, AlN thin films were deposited on Si(lll) substrates to decrease the influence of charging on the analysis of metal/AlN interfaces with x-ray photoelectron spectroscopy (XPS), Thin films of titanium were deposited on bulk ALN substrates by e-gun evaporation and ion beam assisted deposition (IBAD) and deposited on AlN films in situ by e-gun evaporation. Solid-state reaction products and reaction mechanism of the Ti/AlN system annealed at various temperatures and under LEAD were investigated by XPS, transmission electron microscopy (TEM), x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RES). Ti reacted with AlN to form a laminated structure in the temperature range of 600 degrees C to 800 degrees C, The TiAl3 phase was formed adjacent to the AlN substrate, TiN, and Ti4N3-x as well as Ti2N were formed above the TiAl3 layer at the interface, Argon ion bombardment during Ti evaporation promoted the interface reactions. No reaction products were detected for the sample as-deposited by evaporation. However, XPS depth profile of the Ti/AlN/Si sample showed that Ti-N binding existed at the interface between the AIN thin films and the Ti thin films.

Effect of substrate temperature on the deposition of C-N films by pulsed high-temperature C-H-N Plasma CVD

Rather than using conventional low-temperature plasma, the pulsed high-temperature plasma was used to synthesize C-N films. CH4 + N-2 mixture was used as the gas source. The effect of substrate temperature on the deposition was studied. It was found that with the increase of substrate temperature, the deposition rate dropped drastically, the content of H in the films decreased and the hardness of the films was improved; The N/C ratio, however, changed only by a small degree, suggesting that the C and N has been well combined by using high-temperature plasma

New plasma source ion-implantation technique for inner surface modification of materials

Plasma source ion-implantation (PSII) is a non-line-of-sight ion implantation technique for surface modification of materials, but the present technique is only suitable for outer surface modification of targets, not for inner surface modification of targets. In this paper we present a new technique which applies to inner surface implantation. Preliminary experiment results show that this new technique: (1) increases plasma density and uniformity obviously inside the target inner surface; (2) generates a plasma sheath between the inner surface of the target and plasma so as to implant the inner surface of the target effectively; (3) achieves a dose uniformity acceptable for industrial application.

Influence of grid and target radius and ion–neutral collisions on grid-enhanced plasma source ion-implantation process

Grid-enhanced plasma source ion implantation (GEPSII) is a newly proposed technique for inner surface modification of materials with cylindrical geometry. In this paper, a collisional fluid model is used to investigate the ion sheath dynamics between the grid electrode and the inner surface of a cylindrical bore during the GEPSII process. Assuming the initial ion density along the radial direction is not uniform but determined by diffusion mechanisms, the effects of grid electrode radius, target radius and ion-neutral collisions on the ion dose and impact energy are investigated by solving fluid equations for ions coupled with Boltzmann assumption for electrons and Poissons equation. The results show that small gap distance between grid electrode and target is favourable to increase the ion dose and impact energy on the target. In addition, ion-neutral collisions can reduce both the ion dose and impact energy.

Investigation of diffusion across the interface between metal films and AlN or A12O3 substrates

Abstract Vacuum annealing of W films/AlN samples, followed by Rutherford backscattering spectrometry (RBS) measurements, showed that medium energy ion beam assisted deposition (IBAD) techniques could remarkably hinder the interdiffusion of interfacial atoms at elevated temperatures in comparison with evaporated W films/AlN samples. Similar results were observed in Mo thin films/AlN and Mo (or W) thin films/Al 2 O 3 (0001) systems. An IBAD Mo films/Al 2 O 3 (0001) sample was selected so as to investigate the mechanism of medium energy IBAD resulting in a stable interface by high-resolution electron microscopy (HREM). An amorphous layer of 10–12 nm thickness between IBAD Mo films and A1 2 O 3 (0001) substrate was observed.

Inner surface reaction and modification of titanium alloy by a new plasma source ion implantation method

The inner surface of a cylindrical titanium alloy target was successfully implanted with nitrogen ion using a new plasma source ion implantation method. By means of x-ray photoelectron spectroscopy and x-ray diffraction, the reactive phases and their chemical state in the implanted layer were investigated. In order to characterize the modification effect and its uniformity, the retained dose and the microhardness at seven different positions along the axis on the inner surface of the cylindrical target were measured, respectively. The experimental results show that a TiN reactive phase was formed in the implanted layer, which contributed to the improvement of inner surface microhardness. The root-mean-square deviations of retained dose and microhardness measured along the axis of the target are less than 9% and 4%, respectively, which are well within an acceptable tolerance range for metallic applications of ion implantation.