Yazar "Mobtakeri, Soheil" seçeneğine göre listele

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    Characterization of gallium oxide/glass thin films grown by RF magnetron sputtering
    (2020) Mobtakeri, Soheil; Tüzemen, Ebru Şenadım; Özer, Ali; Gür, Emre
    In the present work, Gallium Oxide (Ga2O3) were deposited as thin films by radio frequency(RF) magnetron sputtering at 300 °C substrate temperature on glass substrate using Ga2O3target with 99.99% purity. The crystalline structure, morphology, optical properties of theGallium Oxide films were determined using X-ray diffraction (XRD), scanning electronmicroscopy (SEM) and UV–Visible Spectrometry, respectively. Experimental results showthat annealing has an important role in the changes observed in the characterization of theGallium Oxide thin films. All thin films produced were amorphous, except for the annealedP4-500. SEM pictures reveal the morphology of prepared Gallium Oxide thin films. Therefractive index and real part of complex dielectric constant increased as the film depositionpressure increased
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    The effects of two-stage HT-GaN growth with different V/III ratios during 3D-2D transition
    (IOP PUBLISHING LTD, 2018) Altuntas, Ismail; Demir, Ilkay; Kasapoglu, Ahmet Emre; Mobtakeri, Soheil; Gur, Emre; Elagoz, Sezai
    The aim of the study is to understand the effects of two stages of HT-GaN growth with different V/III ratios on optical, chemical and structural characteristics of the HT-GaN layer. In addition, the effects of two-stage growth on the transport properties has been presented through fabricated Schottky diodes. As the V/III ratio in the 1st stage growth of HT-GaN layer is varied, it has been observed that recovery of reflectance is faster with higher V/III ratios, while no significant effect has been observed by changing the V/III ratios in the 2nd stage of HT-GaN growth. The 2nd stage growth is caused to decrease in screw dislocation densities obtained from the high-resolution x-ray diffraction measurements. The lowest edge type dislocation densities have been obtained for samples with lower V/III ratios in both the 1st and 2nd stages of HT-GaN growth. Well-defined terraces and a few GaN atomic layer surface roughness have been realized through the atomic force microscopy measurements on all the samples. Ga atom bound oxygen states has been investigated through the x-ray photoelectron spectroscopy to find out the V/III ratio effect on the impurity incorporation. An increase in the V/III ratio has given rise to a higher percentage of oxygen incorporation during the 2nd stage of growth. The lowest internal quantum efficiency has been obtained for the samples grown at the highest V/III ratio for both the 1st and 2nd growth stages. Fine excitonic transitions have been indicated by the low temperature high-resolution photoluminescence measurements. Current-voltage measurements performed on the Schottky diodes have shown the effects on the diode parameters.