Conference Papers

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    Synthesis and Optical Characterization of Amaranth Dye Doped Thiourea Barium Chloride (TBC) Single Crystals
    (Elsevier Ltd, 2018) Mahendra, K.; D'Souza, A.; Ifthekarahmed; Udayashankar, N.K.
    Thiourea barium chloride (TBC), Amaranth doped (0.05, 0.1 mM) TBC(ADTBC) crystals were synthesized at room temperature by solvent evaporation process. Structural analysis of TBC and ADTBC were studied using powder XRD, results confirmed that dye got incorporated into the host lattice. Optical analysis of the TBC and ADTBC crystals were carried using UV-Visible and photoluminescence spectrophotometer. Results showed that both pure and dye doped crystals had an absorption peak at around 264 nm. Optical bandgap of the crystal was found to be decreasing as the doping percentage of the crystal increased. Pure and doped crystals exhibit a strong emission peak in the blue region. © 2017 Elsevier Ltd.
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    Structural and optical analysis of silver nanoparticles grown on porous anodic alumina membranes by electro-less deposition
    (Elsevier Ltd, 2019) Ramana Reddy, P.; Ajith, K.M.; Udayashankar, N.K.
    In this paper, we report our studies on silver nanoparticles which were synthesized inside the pores of porous anodic alumina (PAA) membranes by electro-less deposition method. The morphology of silver (Ag) nanoparticles was studied using FE-SEM. The result of FE-SEM showed that the Ag nanoparticles were spherical in shape and spread in uniform manner throughout the membrane. The elemental composition of Ag nanoparticles was investigated by Energy dispersive X-ray (EDX) spectroscopy. Structural characterization using X-ray diffraction pattern showed that PAA was amorphous and silver nanoparticles on PAA were crystalline in nature. Absorbance and luminescent behaviour of PAA and Ag-PAA were studied using UV-Visible and Photoluminescence (PL) spectra. PL spectra results revealed the presence of a strong peak at 392 nm in blue region, confirming the fact that the silver nanoparticles were embedded in the alumina template. © 2019 Elsevier Ltd.
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    Effect of post-deposition annealing ambient on Gallium Oxide (Ga2O3) films
    (SPIE, 2022) Mishra, M.; Saha, R.; Bhowmick, S.; Pandey, S.K.; Chakrabarti, S.
    Gallium Oxide (Ga2O3) is an emerging wideband semiconductor which can be utilize in solar-blind photodetector and high power electronics application. Having a large bandgap and high breakdown field makes Ga2O3 material suitable for these device applications. However, the physical and the optical properties of Ga2O3 can be tailored by changing the annealing ambient and temperature, and understanding how the annealing atmosphere can affect these properties is crucial for designing a next generation optoelectronic devices. Moreover, the presence of defects and impurities can also affect the device parameters. Thus, in this work, we have investigated the influence of post deposition annealing atmosphere on the morphological, structural, and optical properties of Ga2O3 films. The prepared samples were further went through thermal annealing at 800℃ for 30 mins in Nitrogen (N2), and Oxygen (O2) ambient to achieve β-phase of Ga2O3. The structural properties of all the samples were studied by Atomic force microscopy, and X-ray diffraction while the optical properties were studies by UV-Visible, and photoluminescence spectroscopy. We have found monoclinic β-phase in the polycrystalline annealed Ga2O3 samples. The optical band gap of films were increased after annealing and highest band gap is obtained to 5.44eV in N2 annealed sample as compared to as-deposited sample (4.56eV). A broad photoluminescence spectrum ranged from 350 to 480 nm was observed, which further deconvoluted in three peaks at around 378 nm, 399 nm, and 422 nm in as-deposited sample. The same peaks with broad photoluminescence spectrum was found to be blue shifted for annealed samples as compared to the as-deposited. This study will open a new direction in future deep-UV photodetector fabrication. © 2022 SPIE.