Shrook A. Azzez

A highly sensitive flexible SnS thin film photodetector in the ultraviolet to near infrared prepared by chemical bath deposition

This study involves a novel fabrication of a high performance, low cost and flexible (SnS nanoflake based) photodetector on a polyethylene terephthalate (PET) substrate by using chemical bath deposition. The photoresponse properties of the fabricated SnS nanostructure in the ultraviolet (UV) to near infrared (NIR) region were studied. The photodetector was subjected to illumination from four light emitting diodes (LEDs) characterized by spectra peaks of 380, 530, 750 and 850 nm, respectively. The photodetector exhibited a good photoresponse, fast response and high reproducibility with time. The sensitivity values of the photodetector were determined to be approximately 2990, 1604, 2591, and 446 for wavelengths of 380, 530, 750, and 850 nm at a bias voltage of 3 V. At the bias voltage of 5 V, the sensitivity values of 2575, 1262, 1635 and 295 were recorded for 380, 530, 750 and 850 nm respectively. The photodetector also manifests fast photoresponse for the illumination wavelengths. Based on the abovementioned results, in addition to its low cost, flexibility, and non-toxic nature, the SnS photodetector is a promising photoelectronic device that is effectively applicable over the UV-vis-NIR range.

Broadband optical absorption enhancement of N719 dye in ethanol by gold–silver alloy nanoparticles fabricated under laser ablation technique

Abstract. The formation of gold–silver alloy nanoparticles (Au–Ag alloy NPs) by a two-step process with a pulsed Nd:YAG laser without any additives is presented. Mixtures of Au and Ag colloidal suspensions were separately obtained by 1064-nm laser ablation of metallic targets immersed in ethanol. Subsequently, the as-mixed colloidal suspensions were reirradiated by laser-induced heating at the second-harmonic generation (532 nm) for different irradiation periods of time. The absorption spectra and morphology of the colloidal alloys were studied as a function of exposure time to laser irradiation. Transmission electron microscopy revealed the formation of monodispersed spherical nanoparticles with a homogeneous size distribution in all the synthesized samples. UV–vis and photoluminescence spectroscopy measurements were also employed to characterize the changes in the light absorption and emission of N719 dye solution with different concentrations of Au–Ag colloidal alloys, respectively. The localized surface plasmon resonance (LSPR) of Au–Ag alloy NPs enhanced the absorption and fluorescence peak of the dye solution. The mixture of dye molecules with a higher concentration of alloy NPs exhibited an additional coupling of dipole moments with the LSPR, thereby contributing to the improvement of the optical properties of the mixture.

CuS p- type thin film characterization deposited on Ti, ITO and glass substrates using spray pyrolysis deposition (SPD) for light emitting diode (LED) application

The copper sulphide (CuS) thin films were grown with good adhesion by spray pyrolysis deposition (SPD) on Ti, ITO and glass substrates at 200 °C. The distance between nozzle and substrate is 30 cm. The composition was prepared by mixing copper chloride CuCl2.2H2O as a source of Cu2+ and sodium thiosulfate Na2S2O3.5H2O as a source of and S2−. Two concentrations (0.2 and 0.4 M) were used for each CuCl2 and Na2S2O3 to be prepared and then sprayed (20 ml). The process was started by spraying the solution for 3 seconds and after 10 seconds the cycle was repeated until the solution was sprayed completely on the hot substrates. The structural characteristics were studied using X-ray diffraction; they showed covellite CuS hexagonal crystal structure for 0.2 M concentration, and covellite CuS hexagonal crystal structure with two small peaks of chalcocite Cu2S hexagonal crystal structure for 0.4 M concentration. Also the surface and electrical characteristics were investigated using Field Emission Scanning Electron...

Preparation of CuO nanoparticles by laser ablation in liquid

Colloidal Cu nanoparticles (NPs) were synthesized by pulsed Nd:YAG laser ablation in acetone. Cu NPs were converted into CuO. The size and optical properties of these NPs were characterized using an UV/Vis spectrophotometer, transmission electron microscopy, and X-ray diffraction. Cu NPs were spherical, and their mean diameter in acetone was 8 nm–10 nm. Optical extinction immediately after the ablation showed surface Plasmon resonance peaks at 602 nm. The color of Cu NPs in acetone was green and stable even after a long time.

Hydrothermal synthesis of highly crystalline ZnO nanorod arrays: Dependence of morphology and alignment on growth conditions

Highly oriented zinc oxide nanorod were successfully grown on seeded p-type silicone substrate by hydrothermal methode. The morphology and the crystallinty of ZnO c-axis (002) arrays were systematically studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) methods. The effect of seed layer pre-annealing on nanorods properties was explained according to the nucleation site of ZnO nanoparticles on silicon substrate. In addition, the variation of the equal molarity of zinc nitrate hexahydrate and hexamine concentrations in the reaction vessel play a crucial role related to the ZnO nanorods.

Characterization of ZnO/Cu/ZnO multilayers structure for solar cell devices

A series of ZnO/Cu/ZnO multilayer films has been fabricated from zinc and copper metallic targets by simultaneous RF and DC magnetron sputtering. The influences of the ZnO and Cu layer thicknesses, and Ar flow rate on the optical, electrical and structural properties of the films were investigated. The optical and electrical properties of the multilayers were studied by optical spectrometry and four point probe measurements, respectively. The thickness of the ZnO layers were varied between 20 and 60 nm and the Cu layers were between 5 and 15 nm, the optimum thin film structures were deposited under 12 sccm Ar flow rate. Low sheet resistance and high transmittance were obtained when the film was prepared using thickness of ZnO (60 nm)/Cu (15 nm)/ZnO (60 nm).