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Abstract: Segregation of implanted As during steam oxidation of Si wafers is shown to result in a highly enriched, thin layer of As at the interface between the oxide and the underlying Si. Also, the oxidation rate was found to increase by as much as a factor of ∼2 depending on the depth distribution and fluence of the implanted As impurity. The thin As layer collected at the interface can be used in the design of very shallow junctions. This mechanism enables the formation of a narrow, degenerately doped layer of Si, which can be tailored to have a thickness of only few monolayers depending on the fluence of the implantation used. [Copyright &y& Elsevier]

Abstract We report on formation of epi-layer of Si x Ge 1-x by taking standard procedure in CMOS technology. The competitive process of solid solubility of Ge dopant into Si and SiO 2 is the key to engineer atomically sharp, low defect very thin epitaxial layer at the interface of oxide-Si. Oxidation time process was used to control the distribution of the doped Ge ions at the interface of Si with oxide and in the oxide layer. Implanted samples (35 keV and 1 × 1016 Ge+/cm2) were oxidized at 1050 °C for 30–90 min. RBS-Channeling analysis shows two separate peaks of Ge corresponds to different depths after oxidation. Corroborate with high resolution microscopy and elemental analysis, we determined the first peak as enriched layer of Si x Ge 1-x at the interface of SiO 2 Si. Less than 10 nm epitaxially grown interfacial layer is very low in defects, and Ge ions are fully substituted into the host lattice. The second peak originated from diffusion of Ge into SiO 2 resulted in a segregated layer containing Ge in oxide film. Technological demand on forming Si x Ge 1-x layer for CMOS application through standard routes is what we address in this research. Highlights • Ge implantation and dry oxidation were used to form very thin mixed Si x Ge 1-x layer. • A rich Ge layer was formed after dry oxidation at 1050 °C. • Very thin Si x Ge 1-x layer is in epitaxial relation to the silicon substrate. • Some Ge ions are segregated in top oxide layer. [ABSTRACT FROM AUTHOR]

In this study, we propose new approach to study on hydrogen implantation into SiC crystalline structure and its effect on thermal oxidation. This paper has investigated on effects of hydrogen implantation into the surface structure of 6H-SiC crystal before and after thermal oxidation in oxygen ambient. H ions were implanted in SiC with dose of 1×1016 atoms/cm2 and energy of 15 keV. AFM results of implanted and non-implanted areas show that roughness in the implanted area is more than the non-implanted but, we could not observe any evidence of implanting effect in the nano scrapes which were created during polish process. Also, crystal quality, effect of H implantation and depth of maximum concentration were determined by RBS- Channeling. Moreover, it shows that the collision of H ions has affected on the SiC atoms. Distribution and dose of H ions were estimated by ERD technique. Furthermore, bonding between SiC atoms was investigated in implanted and non-implanted areas by FTIR technique. In addition, FTIR results in two areas show a significant difference between both areas before and after oxidation in oxygen ambient. [ABSTRACT FROM PUBLISHER]

Abstract: Porous silicon (PS) is widely utilized in gas sensors. Palladium is a good choice to sensitize the surface of PS to hydrogen. Ideally for highest sensitivity of the sensor, all the pores of PS should be completely covered with palladium. Rutherford backscattering spectroscopy (RBS) technique is routinely used to determine depth profile of elements in thin layers. By using microbeam analysis as a complementary technique, we clearly observed the lateral image of penetrated Pd in depth. In this work, we used electrochemically anodized-silicon wafer doped with Pd by the electroless process. In our analysis, we intentionally characterized both the area of PS where Electric Field is applied during silicon etching (EF area) and the Field Free region (FF area) of the sample. Microbeam analysis show that EF area of the sample is covered with thicker palladium layer, but the pores are rarely filled in this area, while in the FF area of the sample, there is a thin palladium film on the silicon surface, but the pores are partially filled. We used a computational simulation method based on columnar pore structure and linear variation of Pd depth profile in pores and determined the lateral variation of Pd penetration in pores in both parts of the sample. These simulations showed that there are 180±80nm thick Pd layer with 300±200nm penetration in pores in EF region and 80±40nm thin Pd layer with 800±200nm penetrate in pores in FF region. [Copyright &y& Elsevier]

Abstract: A novel vacuum chamber for ion beam analysis of large-size industrial samples – whose analysis are not feasible in conventional ion beam analysis reaction chambers – has been designed, fabricated and successfully tested. Using the newly developed chamber, both PIXE and RBS analyses could be carried out at the same time and on the same point of the samples. Ion beam analysis using this novel chamber lacks the disadvantages of external beam analysis and benefits the advantages of in-vacuum analysis. This has been achieved by designing a tiny open port in the wall of the reaction chamber to be sealed with a small flat area of sample body where its analysis is of interest. As a case study, two samples of gas turbine blades, a corroded one at highly corrosive environment and a refurbished one after application of certain coatings are analysed using the novel chamber. Experimental results confirm the performance and capability of the reaction chamber. [Copyright &y& Elsevier]

Thirty-eight water samples were collected from various areas of Anzali lagoon, Iran. Initial screening of a total of 100 bacterial isolates, resulted in the selection of one isolate with maximum adsorption capacity. It was tentatively identified as Bacillus sp. and named strain GT-83-23. The optimum pH of the medium was found to be 2.0 for Re(VII) adsorption. Uptakes of Re(VII) increased with increasing Re(VII) concentration and decreased sharply by the presence of increasing concentrations of NaCl. The kinetic of Re(VII) sorption by Bacillus sp. GT-83-23 was fast, reaching more than 62% of the total sorption capacity within 5 min. As the cell concentration increased, the amount of Re(VII) adsorbed by each cell (specific uptake) decreased, whereas the total amount of Re(VII) adsorbed enhanced. Cells immobilized in calcium alginate gel took up 77% of the Re(VII). The binding of Re(VII) on the Bacillus sp. GT-83-23 was studied with micro-PIXE.