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Article Citation - WoS: 6Citation - Scopus: 6Modification of Poly(methyl Methacrylate) Surfaces With Oxygen, Nitrogen and Argon Plasma(Amer Scientific Publishers, 2014) Ozgen, Ozge; Özgen, Özge; Hasirci, Nesrin; Özgen, Özge; Physics Group; Physics GroupPoly(methyl methacrylate) (PMMA) is a strong and lightweight material used in wide range of areas changing from lenses to medical and dental devices. In this study, PMMA samples were modified by oxygen, nitrogen and argon plasma with application of 100 watts 13.56 MHz radio frequency (RF) discharge for different periods (5 min, 15 min and 30 min) and the effects of plasma parameters on surface chemistry, hydrophilicity, surface free energy and topography were examined. XPS analysis showed formation of free carbonyl and carbonate groups by oxygen plasma, carboxylic acid and free carbonyl by argon plasma, and imine, primary amine, amide and nitrozo functional groups by nitrogen plasma treatments. For all cases plasma treatment created more hydrophilic surfaces with lower water contact angles than that of pristine PMMA. Also, plasma caused an increase in the surface free energy and its' polar components determined by Geometric Mean, Harmonic Mean, and Acid-Base approaches. AFM results showed increasing roughness parallel to the duration of plasma. As a result, each plasma treatment caused different functionalities and physical topographies on PMMA surfaces and different functionalities can be used for further developments such as binding specific active molecules to design biosensors or medical devices.Article Citation - WoS: 3Performance of the Yb/n< Tunneling Barriers(Amer Scientific Publishers, 2018) Qasrawi, A. F.In this article, the design and performance of the CdSe which are deposited onto thin films of Yb metal is reported and discussed. The thin films of CdSe which are deposited by the physical vapor deposition technique are observed to exhibit slightly deformed hexagonal polycrystalline nature with excess amount of Cd as confirmed by the X-ray, energy dispersive X-ray spectroscopy and scanning electron microscopy techniques. The n-type CdSe is also found to form a Schottky barrier of tunneling type when sandwiched between Yb and carbon. The quantum mechanical tunneling mechanism in this device which was tested and modeled in the frequency domain of 10-150 MHz is found to exhibit average intersite separations of similar to 5 nm. The tunneling device exhibited a widening in the depletion region associated with significantly large capacitance tunability in the studied frequency domain. On the other hand, as an optoelectronic device, the Yb/n-CdSe/C Schottky diode exhibited a responsivity of similar to 0.10 NW, photosensitivity of 6.5 x 10(4) and external quantum efficiency of 54% when biased with 1.0 V and exposed to laser light of wavelength of 406 nm.
