Wang Ke-Ming

Chemical characterization of plasma-polymerized hexamethyldisilazane by nuclear elastic recoil detection

Abstract Chemical composition profiles of plasma-polymerized hexamethyldisilazane thin films, deposited in microwave discharges, were measured by elastic recoil detection (ERD). The main fabrication variable during film deposition was the substrate temperature, which was varied from 25 to 650°C. Hydrogen, carbon and silicon concentrations and profiles to a depth of roughly 1 μm were measured by ERD. These concentrations were compared with results obtained by conventional chemical microanalysis, and agreement was found to be excellent. As in earlier work using other techniques, ERD confirmed the presence of a thin (approximately 50 nm) “oligomeric” layer at the free surface of the films. Erosive radiation damage caused by the probing ion beam on the carbon and hydrogen profiles was observed and investigated.

The range profile of Hg+ in Li0.16Na0.84NbO3

The range profile of Hg+ implanted in Li0.16Na0.84NbO3 at energies from 50 to 350 keV is measured by MeV 4He+ Rutherford back-scattering. A computer program based on the Biersack model has been written to facilitate comparison with the experimental results. It is found that the measured projected range is in good agreement with the calculated value and a marked improvement in the range straggling is obtained when the second-order energy loss is taken into consideration.

Ion beam mixing of AG on glass

Abstract A series of Ag-glass samples have been studied. They were irradiated as a function of bombarding ion species, dose, temperature, and energy. The results by RBS indicate that ion beam mixing of Ag-glass takes place not only at higher energy irradiation (I. OMeV Xe+), but also at lower energy irradiation (120KeV Ar+ and Kr+). The effective diffusion lengths squared, Dt, were introduced for comparison. It is found that Dt is dependent on the nuclear stopping power, dose and irradiation temperature.

Distribution of implanted Hg ions in LiNbO3

Abstract Implanted Hg ions distributions in LiNbO 3 at energies from 50 to 400 keV are studied by 2.1 MeV 4 He 2+ Rutherford backscattering. The values obtained for the mean projected range and range straggling are compared with calculated results based on Biersacks angular diffusion model and TRIM simulation. Good agreement was found within experimental error.

Range distributions of 50–400 keV Hg+in amorphous silicon and Si-Ar binary targets

Abstract Range distributions of 50–400 keV Hg + in amorphous Si and Si-Ar binary targets have been investigated by Rutherford backscattering spectrometry. The Si(100) wafers were amorphized by means of 150 keV Ar + irradiation to a dose of 2 × 10 15 ions/cm 2 . To produce Si-Ar binary targets, the Si(100) wafers were implanted with 150 keV Ar + to a dose of 3 × 10 17 ions/cm 2 . 50–400 keV Hg + were introduced into amorphous Si and Si-Ar binary targets in increments of 50 keV. Parallel scanning of the Hg + beams was used. The measured ranges and range stragglings have been compared to the Biersack theory. The results show that good agreements are found between the experimental and theoretical projected ranges for both Si and Si-Ar, but the predicted range straggling for both Si and Si-Ar are systematically lower than the experimental results in the case of a first order treatment. After correcting for second order energy loss terms, a better agreement for the range straggling is obtained.

Ion-Implanted Waveguides in a Nd3+-Doped Silicate Glass

Monomode enhanced-index Nd3+-doped silicate glass waveguides fabricated by ion implantation are reported. The Nd3+-doped silicate glass was implanted by 3.0 MeV B+ ions, 3.0 MeV O+ ions and 4.5 MeV Ni2+ ions, respectively. A prism-coupling method was carried out to measure dark modes in the Nd3+-doped silicate glass using a model 2010 prism coupler. The moving fibre method was applied to measure the waveguide propagation loss. After a moderate annealing, the 3.0-MeV B+-ion implanted waveguide loss is about 3.54 dB/cm; the 3.0-MeV O+-ion implanted waveguide loss is about 5.36 dB/cm; and the 4.5-MeV the Ni2+-implanted waveguide loss is about 7.55 dB/cm. The results show that with the increasing ion mass, the loss in implanted waveguide is increased.

Positron annihilation, X-ray and ESR studies of iron ion implanted crystals of potassium bromide and quartz

Abstract The association of electron spin resonance. X-ray diffraction and positron annihilation techniques has been applied to the study of radiation-induced defects in iron implanted single crystals of KBr and quartz with the implant dose of 5 × 10 15 ions/cm 2 . Two kinds of defect creation processes due to the ion bombardment are found in these crystals. In the ionic crystal KBr, the F-centers that already existed in the sample before implantation aggregate in the halogen sublattice by electronic processes during ion implantation, and a new crystal structure is formed either due to lattice dilatation caused by F-center aggregation and metallic ion precipitates, or due to the formation of an Fe +3 compound. In quartz, only F-type centers (i.e., E 1 1 centers) are created in the oxygen sublattice through nuclear collision cascades by ion implantation.

Analysis of bromine ion range distributions in glass

MeV 4 He + backscattering has been performed on Br implanted into glass. Analysis of backscattering measurement gives the mean projected range and range straggling of implanted ions. The distributions were obtained by implanting 5 × 10 15 Br + /cm 2 at room temperature at energies from 50 to 400 keV into glass chosen as a typical multielemental insulator. We have used the Biersack theory to calculate mean projected range and range straggling. The measured range and range straggling have been compared to the Biersack model. The results show good agreement between the experimental and theoretical values within the experimental error.

Cs+-K+ Exchange in Z-Cut KTiOPO4 Crystal Covered with Chromium Masking Layer

Cs+-K+ ion exchanges are performed on z-cut KTiOPO4 crystals with chromium coating covered. The temperature of ion exchange is 430°C, and the time range from 15min to 30 min. The dark mode spectra of the samples are measured by the prism coupling method. The channel structures on the samples are observed by a microscope and the near field pattern of the channel waveguides are measured by the end-fire coupling method. The refractive index of the samples increases and the increments at surface are modulated due to the existence of Cr film. In the region covered by Cr film, the refractive index of the samples at the surface increases dramatically in a shallow layer. The results of energy dispersive x-ray spectra indicate that in the region covered with Cr film, Cr ions participate in the ion exchange process, and enhance the refractive index. The results may provide a possibility that achieves index enhancement and Cr doping synchronically.

Tilted Angle Implantation of Xe Ions in potassium Titanyl Phosphate

200 ke V Xe ions were implanted in potassium titanyl phosphate (KTP) at deferent angles: 0°, 45° and 60°. The lateral spread of Xe ions in KTP was studied by Rutherford backscattering of 2.1 Me V He ions. The result is compared with the theoretical prediction. The lateral spread is found in good agreement with calculated value within 17%.