Browsing by Subject "Pulsed Laser Deposition"
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Item Open Access Low temperature thin films transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels(AIP Publishing LLC, 2014) Bolat, S.; Ozgit Akgun, C.; Tekcan, B.; Bıyıklı, Necmi; Okyay, Ali KemalWe report GaN thin film transistors (TFT) with a thermal budget below 250 °C. GaN thin films are grown at 200 °C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3 nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (ION/I OFF) of 103 and sub-threshold swing of 3.3 V/decade. The entire TFT device fabrication process temperature is below 250 °C, which is the lowest process temperature reported for GaN based transistors, so far. © 2014 AIP Publishing LLC.Item Open Access Synthesization of noble metal nanoparticles by pulsed laser ablation method in liquids and thin film applications(2012) Vural, Hüseyin AvniPulsed Laser Ablation in Liquid (PLAL) is promising, alternative, easy, fast and free of agent method for synthesization of nanoparticles (NPs). Various kinds of NPs can be synthesized easily by PLAL, such as base metals, noble metals, semiconductors, nanoalloys, magnetic and core–shell nanostructures. Additionally, crystallized NPs can be easily obtained in one-step procedure by PLAL without subsequent heat-treatments. Synthesization of gold (Au), silver (Ag) and platinum (Pt) NPs with PLAL using Nd: YLF laser (Q-Switched Laser, 527 nm wavelength, 16 W average power, 110 ns pulse duration, and 16 mJ pulse energy for 1 kHz) in different liquid environments is reported. Firstly, Ag, Au and Pt NPs have been synthesized with pulsed Nd: YLF laser in deionized water. Secondly, these NPs have been synthesized in methanol under similar conditions. Colloidal NP solutions are then characterized with Transmission Electron Microscopy, Scanning Electron Microscopy, X-Ray Photoelectron Spectrophotometer, X-Ray Diffractometer and UV-Vis Photospectrometer analysis techniques.In the second part, applications of noble metal nanoparticles have been investigated. Firstly, Au and Ag NPs have been synthesized in Polyvinylpyrolidone solution in order to prepare nanofibrous composites. The Au and Ag NPs embedded in nanofibrous composites then characterized with UV-Vis Photospectrometer and Transmission Electron Microscopy. In addition, AuNPs have been synthesized with varying energies of laser (9,2 mJ, 12 mJ and 16 mJ for 1kHz) in order to understand the role of laser energy on PLAL. Finally, thin-film applications also presented: Pulsed Laser Deposition by PLAL and simple spin-coating deposition with AuNPs synthesized in methanol.