Papers by Author: Khaled Zahraman

Abstract: The quantification of active ingredients (AI) in drugs is a crucial and important step in the drug quality control process. This is usually performed by using wet chemical techniques like LC-MS, UV spectrophotometry and other appropriate organic analytical methods. However, if the active ingredient contains specific heteroatoms (F, S, Cl…), elemental IBA like PIXE and PIGE techniques, using small tandem accelerator of 1-2 MV, can be explored for molecular quantification. IBA techniques permit the analysis of the sample under solid form, without any laborious sample preparations. In this work, we demonstrate the ability of the Thick Target PIXE technique for rapid and accurate quantification of both low and high concentrations of active ingredients in different commercial drugs. Fenofibrate, a chlorinated active ingredient, is present in high amounts in two different commercial drugs, its quantification was done using the relative approach to an external standard. On the other hand, Tiemonium methylsulfate which exists in relatively low amount in commercial drugs, its quantification was done using GUPIX simulation code (absolute quantification) The experimental aspects related to the quantification validity (use of external standards, absolute quantification, matrix effect,...) are presented and discussed.

Abstract: In this work the capability of the proton induced X-ray emission (PIXE) technique to monitor a rapid, non-destructive and accurate quantification of Al on or inside SiC is discussed. Optimization of PIXE acquisition parameters was performed using as reference, a thin Al film (2.5 nm) thermally evaporated onto silicon carbide substrate. In order to improve the sensitivity for Al detection and quantitative determination, a systematic study was undertaken using proton ion beam at different energies (from 0.2 to 3 MeV) with a different tilting angle (0°, 60°, and 80°). The limit of detection (LOD) was found to be lower than 0.02 nm. The optimum PIXE conditions (energy, angle) were applied for determining the Al doping concentration in thin (1 µm) 4H-SiC homoepitaxial layer. The Al concentration as determined by PIXE was found to be 3.9x1020 at/cm3 in good agreement with SIMS measurements, and the LOD was estimated to be 6x1018 at/cm3.

Abstract: Vapor-Liquid-Solid was used for growing boron doped homoepitaxial SiC layers on 4HSiC( 0001) 8°off substrates. Si-based melts were fed by propane (5 sccm) in the temperature range 1450-1500°C. Two main approaches were studied to incorporate boron during growth : 1) adding elemental B in the initial melt, with two different compositions : Si90B10 and Si27Ge68B5; the growth was performed at 1500°C; 2) adding B2H6 (1 to 5 sccm) to the gas phase during growth with a melt composition of Si25Ge75; the growth was performed at 1450°C. In most cases, the growth time was limited by liquid loss due to wetting on the crucible walls. The longer growth duration (1h) was obtained when adding B2H6 to the gas phase. In the case of Si90B10 melt, the surface morphology exhibits large and parallel terraces whereas the step front is more undulated when adding Ge. Raman and photoluminescence characterizations performed on these layers confirmed the 4H polytype of the layers in addition to the presence of B which results in a strong B-N donor-acceptor band. Particle induced γ-ray emission was also used to detect B incorporation inside the grown layers.