Mohammad Noroozi

Characterization of Ni(Si,Ge) films on epitaxial SiGe(100) formed by microwave annealing

Microwave annealing (MWA) is investigated as an alternative technique to rapid thermal processing with halogen lamp heating (RTP) for low-temperature silicide formation on epitaxially grown Si0.81Ge0.19 layers. Phase formation, resistivity mapping, morphology analysis, and composition evaluation indicate that the formation of low-resistivity NiSi1−xGex by means of MWA occurs at temperatures about 100u2009°C lower than by RTP. Under similar annealing conditions, more severe strain relaxation and defect generation are therefore found in the remaining Si0.81Ge0.19 layers treated by MWA. Although silicidation by microwave heating is in essence also due to thermal effects, details in heating mechanisms differ from RTP.

1,3-Dibromo-5,5-dimethylhydantoin (DBH) as a Mild and Efficient Catalyst for Chemoselective Thioacetalization of Carbonyl Compounds and Dethioacetalization Under Mild Conditions

Hydantoin bromide is an effective catalyst for chemoselective thioacetalization of aldehydes in the presence of ketones under neutral conditions. In addition, a simple and efficient procedure for the deprotection of 1,3-dithianes and 1,3-dithiolanes of aromatic, aliphatic, and α,β-unsaturated aldehydes and ketones in solvent-free conditions to the corresponding parent carbonyl compounds was successfully carried out with hydantoin bromide in excellent yields. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Electrochemical oxidation and adsorption of hematoxylin at glassy carbon electrode in various pH values

Electrochemical oxidation of hematoxylin has been studied using cyclic voltammetry, differential pulse voltammetry, chronocoulometry and controlled potential coulometry. It indicates that not only electrochemical behavior of hematoxylin depends on the pH, but also its behavior depends on the concentration. The adsorption activity of hematoxylin and its oxidation products on the surface of the glassy carbon electrode was found to vary in the order hematoxxa0>xa0hemateinxa0>xa0hematoxylin. In addition, it is found that adsorption of hematoxylin depends on the pH and increases with decreasing pH. It is also found that at pHs lower than pKa1, the adsorption of hematoxylin on the surface of the glassy carbon electrode is high. Furthermore, the orientation of adsorbed hematoxylin on the surface of glassy carbon electrode was estimated. The results show that the orientation of adsorbed hematoxylin molecules at glassy carbon surface is endwise.

Electrical properties of sub-100 nm SiGe nanowires

In this study, the electrical properties of SiGe nanowires in terms of process and fabrication integrity, measurement reliability, width scaling, and doping levels were investigated. Nanowires were fabricated on SiGe-on oxide (SGOI) wafers with thickness of 52 nm and Ge content of 47%. The first group of SiGe wires was initially formed by using conventional I-line lithography and then their size was longitudinally reduced by cutting with a focused ion beam (FIB) to any desired nanometer range down to 60 nm. The other nanowire group was manufactured directly to a chosen nanometer level by using sidewall transfer lithography (STL). It has been shown that the FIB fabrication process allows manipulation of the line width and doping level of nanowires using Ga atoms. The resistance of wires thinned by FIB was 10 times lower than STL wires which shows the possible dependency of electrical behavior on fabrication method.

Fabrication and thermoelectric characterization of GeSn nanowires

In this study, GeSn nanowires (NWs) were fabricated and the thermoelectric performance in terms of power factor and contact resistance have been investigated and compared to Ge and Si. The ohmic contact to the NWs was made by Pt/Ti whereas low contact resistance was obtained by Ni-GeSn (or Ni-Ge) layers. A detailed investigation was performed to process towards low resistance Ni-GeSn phase for GeSn NWs. The phase formation of Ni-GeSn layers was examined by x-ray diffraction (XRD) and the residual strain in GeSn beneath the Ni-GeSn was also measured by high resolution reciprocal lattice mapping (HRRLM). It was demonstrated that Ni reaction with GeSn layer resulted in strain reduction in the remained GeSn material due to Ni outdiffusion to the GeSn NWs demonstrated higher Seebeck coefficient compared to Ge and Si NWs, which suggest promising thermoelectric properties in GeSn.

One-pot tandem reactions for direct conversion of thiols and disulfides to sulfonic esters, and Paal–Knorr synthesis of pyrrole derivatives catalyzed by TCCA

A convenient synthesis of sulfonic esters from thiols and disulfides is described. In situ preparation of sulfonyl chlorides from thiols is accomplished by oxidation with trichloroisocyanuric acid (TCCA), tetra-butylammonium chloride (t-Bu4NCl), and water. The sulfonyl chlorides are then further allowed to react with phenol derivatives in the same reaction vessel. Also, a facile synthesis of N-substituted pyrroles by the reaction of hexane-2,5-dione with primary amines has been accomplished using TCCA as a catalyst under mild condition with excellent yields.

Schiff base Mn(III) and Co(II) complexes coated on Co nanoparticles: an efficient and recyclable magnetic nanocatalyst for H2O2 oxidation of sulfides to sulfoxides

In this paper, an effective and selective heterogeneous catalyst was produced by immobilization of manganese and cobalt Schiff base-complexes on Co magnetite nanoparticles (MNP). The catalysts Co@SiO2[(EtO)3Si–L3]/M (M = Mn(III) and Co(II)) were synthesized using Co@SiO2 core–shell nanoparticles and amino-functionalized Co@SiO2. The Schiff base ligand Co@SiO2[(EtO)3Si–L3] was synthesized by reacting Co@SiO2 core–shell nanoparticles with 2-hydroxy 1-naphthaldehyde for the synthesis of Co@SiO2[(EtO)3Si–L3]/M. The catalysts were characterized by several techniques, such as FT-IR, TEM, XRD, TGA and VSM. The catalytic activities of the prepared catalysts were studied by oxidation of sulfides to the sulfoxides under different conditions. These catalysts can be easily recovered and reused in at least seven sequential cycles without considerable leaching and loss of reactivity.

Laboratory Frontiers in Determining the Packing Style Effect in Carbon Dioxide Hydrates Formation

Methane production in sequestration process and reducing atmospheric carbon dioxide, a main source of greenhouse gas, has been accentuated recently. An orderly packing style for hydrate will play a fundamental role in hydrate formation rate and efficiency of free water. Surfactant has been reported to help orient hydrocarbon hydrate packing along a metal wall. In this work, it was shown that hydrate packing styles played an important role in carbon dioxide hydrate formation rate. Packing facilitates a high hydrate formation rate and high percentage conversion. Furthermore, in this research, a camera with borescope was used to observe and record the image of carbon dioxide hydrate when it formed with addition of Surfactin, Emulsan, Rhamnolipid, SDS micellar, FS-62/SDS and FSP/SDS into the water solution. We have shown that a full development of the hydrate in the test cell could be obtained with use of FS-62/SDS or FSP/SDS.