Browsing by Subject "Photoresponses"
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Item Open Access Controlling the photoconductivity: graphene oxide and polyaniline self assembled intercalation(American Institute of Physics Inc., 2015) Vempati S.; Ozcan, S.; Uyar, TamerWe report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with -OH and -COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(RDark - RUV-Vis)/RDark and R corresponds to the resistance of the device in dark or UV-Vis illumination. To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, -111%, -51%, and +58%, respectively.Item Open Access High-speed solar-blind AlGaN-based metal-semiconductor-metal photodetectors(Wiley, 2003) Bıyıklı, Necmi; Kimukin, İbrahim; Kartaloğlu, Tolga; Aytür, Orhan; Özbay, EkmelSolar-blind AlGaN metal-semiconductor-metal (MSM) photodetectors with fast pulse response have been demonstrated. The devices were fabricated on MOCVD-grown epitaxial Al0.38Ga0.62N layers, using a microwave compatible fabrication process. The photodiode samples exhibited low leakage with dark current densities below 1 × 10-6 A/cm 2 at 40 V reverse bias. Photoconductive gain-assisted photoresponse was observed with a peak responsivity of 1.26 A/W at 264 nm. A visible rejection of ∼3 orders of magnitude at 350 nm was demonstrated. Temporal high-speed measurements at 267 nm resulted in fast pulse responses with 3-dB bandwidths as high as 5.4 GHz. This corresponds to a record high-speed performance for solar-blind detectors. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA.Item Open Access Thin film MoS2 nanocrystal based ultraviolet photodetector(Optical Society of American (OSA), 2012) Alkis, S.; Öztaş, T.; Aygün L.E.; Bozkurt F.; Okyay, Ali Kemal; Ortaç, B.We report on the development of UV range photodetector based on molybdenum disulfide nanocrystals (MoS2-NCs). The inorganic MoS2- NCs are produced by pulsed laser ablation technique in deionized water and the colloidal MoS2-NCs are characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction and UV/VIS absorption measurements. The photoresponse studies indicate that the fabricated MoS 2- NCs photodetector (MoS2-NCs PD) operates well within 300-400 nm UV range, with diminishing response at visible wavelengths, due to the MoS2- NCs absorption characteristics. The structural and the optical properties of laser generated MoS2-NCs suggest promising applications in the field of photonics and optoelectronics. © 2012 Optical Society of America.