SYNTHESIS OF CARBON DOTS (CDS) AND DETERMINATION OF OPTICAL GAP ENERGY WITH TAUC PLOT METHOD

Carbon Dots (CDs) which have been synthesized using the laser ablation method show the presence of UV-Vis absorption in the wavelength range of 303 nm to 333 nm for absorbance and 495 nm to 503 nm for fluorescence. Changes in the time duration 1, 2, 3 hours of CDs resulted in changes in the optical energy gap. The optical energy gap valuesare distinguished by the type of indirect transition (n=2) is 3.40 eV (1 hour), 3.15 eV (2 hour), 2.85 eV (3 hour) and direct transition (n=1/2) is 2.58 eV (1 hour), 2.31 eV (2 hour), 1.70 eV (1 hour).

Study on Fabrication and investigation of the effects of copper salt precursor with different anions SO42-, Cl-, CH3COO- and NO3- on the structure and photocatalytic properties for decomposition of methyl orange dye of octahedral Cu2O nanoparticles

The octahedra single-phase Cu2O nanoparticles were fabricated from copper salts precursors with different anions including SO42-, Cl-, CH3COO- and NO3-. The prepared materials were characterized by: XRD, Raman shift, SEM, solid UV-vis absorption spectra. The photocatalytic activity and decomposition reaction kinetics for methyl orange dye of the prepared Cu2O samples under visible light irradiation were also studied in this experiment. The results showed that the fabricated Cu2O materials all had a nanometer-sized crystal particles arranged in about of 300-1000 nm with the octahedral particle shape. The narrow optical gap energy of Cu2O samples achieved Eg» 1.83-2.01 eV. The fabricated Cu2O samples all had the high photocatalytic efficiency in decomposition of methyl orange dye (MO) under visible light when added with H2O2 assisted catalyst. The photocatalytic efficiency of the Cu2O-(SO42-)/H2O2 sample was the highest, reaching 99.2% with the rate constant k= 0.10132 min-1. The photocatalytic efficiency of the Cu2O-(CH3COO-)/H2O2 sample was the smallest, reaching 97.6% with the rate constant k= 0.09098 min-1

Synthesis and Characterization of Benzodithiophene (BDT) Quinoid Compounds as a Potential Compound for n-Type Organic Thin-Film Transistors (OTFT)

Two potential compounds as an n-Type organic thin-film transistor (OTFT) from benzodithiophene (BDT) derivatives have been synthesized and characterized. BDT was chosen as the core because it has π-conjugated bonds, rigid structures, and planar. Quinoid structure with end-cap (terminal group) in the form of dicyanomethylene is used because it can lower the LUMO value of the compound, and side chains are selected in the form of alkoxy so that two BDT derivatives are obtained namely BDTQ-6 (hexyloxy) and BDTQ-10 (decyloxy). Based on the results of TGA, BDTQ-6 and BDTQ-10 have decomposition points of 183°C and 203°C, which indicate the compound has excellent thermal stability. From the UV-Vis measurement, the λmax value of the two compounds is 599 nm with optical gap energy (Eg°pt) of 1.7 eV. From the DPV measurement, the LUMO value for the two compounds is -4.3 eV, with an energy gap (Eg) of 1.69 eV (BDTQ-6) and 1.70 eV (BDTQ-10). Based on observations of the crystal structure through x-ray diffraction, it was found that the BDTQ-10 crystal has a "brick type" layer arrangement with a distance between layers of 3.55 Å. With excellent thermal stability and suitable LUMO values and energy gaps, it is expected that BDTQ-6 and BDTQ-10 compounds have the potential to be n-Type OTFT materials.

Study of the optical and structural properties of the (ZnO) membrane, which is prepared by the method of thermal steaming by using the closed oven

This study investigated the optical and structural properties of the (ZnO) membrane, which is prepared by the method of thermal steaming in the vacuum by using the closed oven on glass platforms at room temperature. The crystallization of the membranes prepared by X-ray diffraction pattern was diagnosed. The membranes were found to be polymorphic with hexagonal structure and crystal direction (002), the membranes were annealed for (5,15,25) min at (510°C),the results showed the increased height of peaks with their intensity and decreases in the optical gap energy. The study of optical properties also included the recording of both the absorption spectra and the permeability spectrum of the prepared membranes at the wavelength range (250-1100) nm, Also, the rest of the optical constants were calculated as functions of the photon energy, including (absorption coefficient, extinaction cofficient), Where the value of the absorption coefficient for ZnO thin films varies from (1.4 cm-1 to 2.09cm-1), and the value of extinaction coefficient varies from (0.6 to 0.38). Transmission spectra showed highly transparent films with band gap energy varies ranging from 3.47ev to 3.3 eV. http://dx.doi.org/10.25130/tjps.24.2019.032

Mechanical and Optical Properties of Thin Film Titanium Nitride (TiN) Resulting from Deposition DC Sputtering

Titanium nitride (TiN) thin film was successfully grown on the surface of stainless steel 304 (SS 304) and preparate glass using the direct current sputtering method. The fabrication was done at high voltage 2.5 kV, sputtering current 40 mA, and deposition time 1 hour. The characterization was carried out using a Micro Hardness Tester and UV-Vis Spectrophotometer. Based on mechanical properties, the hardness results of deposition on SS 304 obtained vickers hardness value of 153.59 HVN and thin film thickness was preparate glass 172.61 nm. Whereas optical properties, from testing the transmittance of thin films TiN measured at a wavelength range of 300 nm - 800 nm, the thin film TiN optical gap energy is 3.51 eV.

PROPERTIES OF LOW-LEVEL Sn-DOPED In2S3 FILMS DEPOSITED BY SPRAY PYROLYSIS TECHNIQUE

Tin-doped indium sulfide films were grown on glass substrates by spray pyrolysis technique at low different Sn:In atomic ratio in the starting solution and optimum experiment conditions ([Formula: see text]C, S:[Formula: see text]). The tin to indium molar ratio Sn:In was varied from 0 to [Formula: see text] in the solution. The obtained films with 2[Formula: see text][Formula: see text]m of thickness, are perfectly adhered, homogenous and uniform on the substrates. X-ray diffraction study reveals that all the films are formed in [Formula: see text] phase grown preferentially along (400). These films lose the orientation with increasing tin doping level. The crystallite size of undoped film was 48.8[Formula: see text]nm, which increases to 59.2[Formula: see text]nm corresponding to the film grown with Sn:[Formula: see text]. Raman analysis shows different peaks related to In2S3 phase. Optical analysis shows that these films are transparent in the visible and near IR with a transmittance higher than 85%. The optical gap energy is found to be direct and varies from 2.61[Formula: see text]eV to 2.76[Formula: see text]eV with the increase of Sn:In ratio from 0 to [Formula: see text]. The films are [Formula: see text] type and Sn doping improves considerably their conductivity. The photoluminescence behavior of In2S3:Sn films was also studied.

Analytical study of high absorption region of the absorption edge of a-Si:H using nonlinear regression method

This research is concerned with the re-analysis of optical data (the imaginary part of the dielectric function as a function of photon energy E) of a-Si:H films prepared by Jackson et al. and Ferlauto et al. through using nonlinear regression fitting we estimated the optical energy gap and the deviation from the Tauc model by considering the parameter of energy photon-dependence of the momentum matrix element of the p as a free parameter by assuming that density of states distribution to be a square root function. It is observed for films prepared by Jackson et al. that the value of the parameter p for the photon energy range is is close to the value assumed by the Cody model and the optical gap energy is which is also close to the value of the Cody gap of these films. While for the films prepared by Ferlauto et al. the value of the parameter is equal to and .