حيدر جواد مكطوف

Some gallium-doped zinc oxide nanofilms (GZONFs) with diverse morphologies were produced on the p-type Si (100) substrate by the sol–gel united spin coating. The thermally annealed nanofilms were characterized using different techniques to determine the influence of various Ga contents (0–5%) on their structures, morphologies, optical and electrical characteristics. The XRD patterns of the as-prepared nanofilms displayed the existence of the single-phase polycrystalline particles with varying sizes (55–36 nm). The band gap values of these GZONFs were ranged from 3.227–3.269 eV. The nanofilm produced with 1% of Ga exhibited the minimal electrical resistivity ≈ 4.6429 × 10–3 Ω cm, highest carrier density ≈ 1.37648 × 1020 cm−3 and Hall mobility ≈ 9.779 cm2/V s. It was shown that the overall properties of the proposed GZONFs can be customized by adjusting the concentration of Ga doping.

Aluminum (Al) and Gallium (Ga) co-doped ZnO nanostructures (AGZO NSs) were prepared on p-type Si(100) substrate using sol-gel united spin coating method. Ga contents were varied from 1 to 5 at% at fixed Al doping (1 at%). Synthesized samples were annealed at 500 °C for 3 h. The structural, morphological, and electrical property of the optimum sample (containing 3 at% of Ga) were determined. Optimum AGZO NSs enclosing highest density of nanorod (NR) arrays were selected to fabricate a hydrogen gas (H2) sensor. As-grown AGZO NSs revealed hexagonal wurtzite structure with mean grain size ≈ 41.20 nm and resistivity ≈ 0.6475 × 10−2 Ω cm. The gas sensing attributes of the developed sensor was evaluated for two different temperatures (at 100 and 150 °C) under varying gas H2 contents (from 250 to 1750 ppm). Furthermore, the selectivity of the AGZO NSs for three different gases such as H2, CO and CH4 were examined. The sensitivity of the sensor at 100 °C was augmented sharply from 60% to 385% with the increment of H2 gas contents from 250 to 1750 ppm. This enhancement was attributed to the increases of hydrogen gas current (IH) and good stability of the air atmosphere. The synthesized AGZO NSs have high potential for gas sensing, photovoltaic and field emission applications.

The influence of annealing time on the structure, morphology and photoluminescence behavior (Al)/(Ga) co-doped ZnO (AGZO). nanofilms are grown on the p-type Si(100) substrate via combined sol-gel, spin coating annealed in air at 500 °C at 0–3 h. Samples are characterized using XRD, TEM, AFM, FESEM, EDX, (PL) and Raman measurements. XRD pattern confirmed the growth of highly poly-crystalline hexagonal wurtzite structure of ZnO with preferred orientation along (101) direction. At (3 h) is found to cause lattice contraction and strain relaxation. TEM images revealed the nucleation of nanoparticles (NPs) and SAED pattern identified the lattice parameter. Raman spectra of AGZO exhibited optical and acoustic modes. FESEM displayed an increase in the particles size and number of nanoflakes with increasing annealing time. EDX detected right elemental traces. PL revealed an intense emission peak centered at 3.23 eV, which is continuously shifted toward lower frequency with increasing time.