Influence of nitrogen implantation into the buried oxide on the radiation hardness of silicon-on-insulator wafers

In order to improve the total-dose radiation hardness of the buried oxide of separation by implanted oxygen silicon- on-insulator wafers, nitrogen ions were implanted into the buried oxide with a dose of 1016 cm-2, and subsequent annealing was performed at 1100 ℃. The effect of annealing time on the radiation hardness of the nitrogen implanted wafers has been studied by the high frequency capacitance-voltage technique. The results suggest that the improvement of the radiation hardness of the wafers can be achieved through a shorter time annealing after nitrogen implantation. The nitrogen-implanted sample with the shortest annealing time 0.5 h shows the highest tolerance to total-dose radiation. In particular, for the 1.0 and 1.5 h annealing samples, both total dose responses were unusual. After 300-krad（Si） irradiation, both the shifts of capacitance-voltage curve reached a maximum, respectively, and then decreased with increasing total dose. In addition, the wafers were analysed by the Fourier transform infrared spectroscopy technique, and some useful results have been obtained.

The Effects of Low-Energy Nitrogen Ion Implantation on Pollen Exine Substructure and Pollen Germination of Cedrus deodara

The aim of this study is to investigate the biological effects of ion beams on pollen. Pollen grains of Cedrus deodara were implanted with 30 keV nitrogen ion beams at doses ranging from 1 × 10^15 ions/cm^2 to 15 × 10^15 ions/cm^2. The effects of N^＋ implantation on the pollen exine substructure were examined using an atomic force microscope （AFM）, and the structure and morphology of pollen and pollen tubes were observed using a laser scanning confocal microscope （LSCM）. AFM observations distinctly revealed the erosion of the pollen exine caused by N^＋ implantation in the micrometer to nanometer range. Typical results showed that the erosion degree was linearly proportional to the ion dose. Pollen germination experiments in vitro indicated that N^＋ implantation within a certain dose range increased the rate of pollen germination. The main abnormal phenomena in pollen tubes were also analyzed. Our results suggest that low energy ion implantation with suitable energy and dosage can be used to break the pollen wall to induce a transfer of exogenous DNA into the pollen without any damage to the cytoplasm and nuclei of the pollen. The present study suggests that a combination of the method of ion-beam-induced gene transfer and the pollen-tube pathway method （PTPW） would be a new plant transformation method.

Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

in order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600℃ with a dose of 4x 1018 ions' cm-2. Using the Plasma Source ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

Total dose radiation response of modified commercial silicon-on-insulator materials with nitrogen implanted buried oxide

Nitrogen ions of various doses are implanted into the buried oxide （BOX） of commercial silicon-on-insulator （SOI） materials, and subsequent annealings are carried out at various temperatures. The total dose radiation responses of the nitrogen-implanted SOI wafers are characterized by the high frequency capacitance-voltage （C-V） technique after irradi- ation using a Co-60 source. It is found that there exist relatively complex relationships between the radiation hardness of the nitrogen implanted BOX and the nitrogen implantation dose at different irradiation doses. The experimental results also suggest that a lower dose nitrogen implantation and a higher post-implantation annealing temperature are suitable for improving the radiation hardness of SOI wafer. Based on the measured C V data, secondary ion mass spectrometry （SIMS）, and Fourier transform infrared （FTIR） spectroscopy, the total dose responses of the nitrogen-implanted SOI wafers are discussed.

Optical and magnetic properties of nitrogen ion implanted MgO single crystal

The microstructure, optical property and magnetism of nitrogen ion implanted single MgO crystals are studied. A parallel investigation is also performed in an iron ion implanted single MgO sample as a reference. Large structural, optical and magnetic differences are obtained between the nitrogen and iron implanted samples. Room temperature ferromagnetism with a fairly large coercivity field of 300 Oe （1 Oe=79.5775 A/m）, a remanence of 38% and a slightly changed optical absorption is obtained in the sample implanted using nitrogen with a dose of 1 × 10^18 ions/cm^2. Transition metal contamination and defects induced magnetism can be excluded when compared with those of the iron ion implanted sample, and the nitrogen doping is considered to be the main origin of ferromagnetism.

SURFACE ANALYSES OF NITROGEN ION IMPLANTED Ti6Ai4V ALLOY

The techniques for surface analysis including AES,XPS and SIMS were employed to study the chemical composition and bond valence of nitrogen ion implanted surface of surgical implantation service alloy Ti6Al4V.The depth of implanted nitrogen ions and the sputtering rate of argon beams were determined using a profilometer.It was found that the combination of injected nitrogen ions with titanium resulted in the formation of hard TiN particles and the profile of nitrogen concentration approximately displayed gaussian distribution.The total depth of implanted nitrogen is about 350 nm and its maximum concentration appears in the depth of about 140 nm from the surface,in which the concentration ratio of nitrogen to titanium may be up to 1.1.

Morphological and Anatomical Assessment of KDML 105 (Oryza sativa L.spp.indica) and Its Mutants Induced by Low-Energy Ion Beam

Thai jasmine rice KDML 105 is consumed around the world. BKOS, PKOS and TKOS are new cultivars produced from low-energy ion beam induction in KDML 105. The purpose of this study is to compare the morphology and anatomy between KDML 105 and the three new cultivars. Seeds of the four cultivars were germinated and grown in pots until flowering phase. The plants＇ organs were observed and the lengths of culms, ligules, leaves and panicles were measured. Leaf surface area was calculated and numbers of roots, spikelets and tillers were counted. BKOS and PKOS had significantly shorter culms than KDML 105 and TKOS. The largest leaf area was found in KDML 105 followed by TKOS, BKOS and PKOS, respectively. Numbers of roots and tillers in BKOS and TKOS were significantly fewer than those in KDML 105 and PKOS. The number of spikelets per plant in BKOS was the lowest among all cultivars. For anatomical comparison, cross sections of culms and roots were observed. All plants had a similar arrangement of tissues, but the number and size of cells were different. Furthermore, longitudinal sections of culms showed that the lengths of epidermal and parenchyma cells were directly related with the length of the culm. To compare the leaves, both stomata and epidermal cells were counted and the lengths of the guard cells were measured. The lengths of guard cells of BKOS and PKOS were shorter, but the stomatal density and the stomatal index were significantly greater than those of KDML 105. For TKOS, though the length of guard cells was shorter than that in KDML 105, the difference was not significant. However, the stomatal density and stomatal index were significantly higher than those in KDML 105.

AUGER STUDY OF CARBON LAYER ON ON IMPLANTED STEEL SURFACE

The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.

Influence of nitrogen dose on the charge density of nitrogen-implanted buried oxide in SOI wafers

To harden silicon-on-insulator（SOI） wafers fabricated using separation by implanted oxygen（SIMOX） to total-dose irradiation,the technique of nitrogen implantation into the buried oxide（BOX） layer of SIMOX wafers can be used.However,in this work,it has been found that all the nitrogen-implanted BOX layers reveal greater initial positive charge densities,which increased with increasing nitrogen implantation dose.Also,the results indicate that excessively large nitrogen implantation dose reduced the radiation tolerance of BOX for its high initial positive charge density. The bigger initial positive charge densities can be ascribed to the accumulation of implanted nitrogen near the Si-BOX interface after annealing.On the other hand,in our work,it has also been observed that,unlike nitrogen-implanted BOX,all the fluorine-implanted BOX layers show a negative charge density.To obtain the initial charge densities of the BOX layers,the tested samples were fabricated with a metal-BOX-silicon（MBS） structure based on SIMOX wafers for high-frequency capacitance-voltage（C-V） analysis.