Hani Khallaf

Investigation of chemical bath deposition of ZnO thin films using six different complexing agents

Chemical bath deposition of ZnO thin films using six different complexing agents, namely ammonia, hydrazine, ethanolamine, methylamine, triethanolamine and dimethylamine, is investigated. As-grown films were mainly ZnO2 with a band gap around 4.3?eV. Films annealed at 400??C were identified as ZnO with a band gap around 3.3?eV. X-ray diffraction and micro-Raman spectroscopy revealed that as-grown films consist mainly of cubic zinc peroxide that was transformed into hexagonal ZnO after annealing. Rutherford backscattering spectroscopy (RBS) detected excess oxygen content in ZnO films after annealing. Fourier transform infrared spectroscopy of as-grown films showed a broad absorption band around 3300?cm?1 suggesting that the as-grown films may consist of a mixture of zinc peroxide and zinc hydroxide. X-ray photoelectron spectroscopy multiplex spectra of the O 1s peak were found to be consistent with film stoichiometry revealed by RBS. High-resolution transmission electron micrographs showed small variations of the order of 10?nm in film thickness which corresponds to the average grain size. A carrier density as high as 2.24?1019?cm?3 and a resistivity as low as 6.48 ? 10?1???cm were obtained for films annealed at 500??C in argon ambient.

Investigation of aluminium and indium in situ doping of chemical bath deposited CdS thin films

Aluminum and indium in situ doping of CdS using chemical bath deposition (CBD) is investigated. The effects of Al and In-doping on optical properties as well as on electrical properties, crystal structure, chemistry and morphology of CdS films are studied. Al doping of CdS using CBD is shown to be successful where a resistivity as low as 4.6 × 10−2 Ω cm and a carrier density as high as 1.1 × 1019 cm−3 were achieved. The bandgap of Al-doped films decreases to a minimum of 2.26 eV, then slightly increases and finally saturates at 2.30 eV as the [Al]/[Cd] ratio in solution increases from 0.018 to 0.18. X-ray diffraction studies showed Al3+ ions entering the lattice substitutionally at low concentration and interstitially at high concentration. Phase transition, due to annealing, and induced lattice damage, due to doping, were detected by micro-Raman spectroscopy. Film stoichiometry was found to be sensitive to Al concentration, while film morphology was unaffected by Al doping. Indium doping using CBD, however, was found to be highly unlikely due to the low solubility of indium sulfide. Instead, the formation of InS/In2S3 dominated the deposition process over CdS.

Microstructures and Magnetism of Silicon co-implanted with Manganese and Carbon ions

Dilute magnetic semiconductors based on transition metal doped silicon have attracted intense interest in recent years due to their compatibility with current silicon technology. Here we present transmission electron microscopy, secondary ion mass spectrometry and ferromagnetic resonance studies of silicon implanted with 1×1016 ions/cm2 of Mn ions and silicon co-implanted with both 1×1016 ions/cm2 of Mn ions and 2×1016 ions/cm2 of carbon ions at a substrate temperature of 350 °C. Afterward, the samples were annealed at temperatures between 800 and 1000°C. The SIMS results show a marked difference between the two specimens while the TEM results show similar features in terms of Mn precipitation and particle evolution. The carbon implanted specimens show additional features that appear to be amorphous silicon pockets within the crystalline implant region. Only one specimen (Mn only implant, unannealed) showed any ferromagnetic properties.

A Study of the Effect of Different Cadmium Sources on Chemical Bath Deposited CdS Thin Films

A comprehensive study of the effect of the cadmium source on chemical bath deposited cadmium sulfide thin films is reported. Four different cadmium sources, namely cadmium sulfate, cadmium chloride, cadmium iodide, and cadmium acetate have been used. Single-dip, for 15 minutes, as well as multi-dip depositions (four successive depositions for 8-12 minutes each) were carried out at 70oC on quartz substrates. The effect of changing the cadmium source on the film optical/electrical properties as well as the film thickness was studied. Hall Effect measurements were carried out for all films as well as Rutherford Back Scattering (RBS), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM).