Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Conference Object Citation - WoS: 6Citation - Scopus: 101/F Noise in Hydrogenated Amorphous Silicon-Germanium Alloys(Institute of Electrical and Electronics Engineers, 2003) Johanson, Robert E.; Güneş, Mehmet; Kasap, Safa O.Measurements were made of conductance noise of a-Si:H and a-Si 1-xGex:H in two different geometries: one where the current flow is transverse to the surface and the other where it is longitudinal to the surface. Because of the large change in sample resistance between the two geometries, it was not possible to measure both geometries at the same temperature. For both geometries, alloyinzg with up to 40% Ge reduces the noise magnitude by several orders of magnitude over that found in a-Si:H. The decrease is incompatible with several popular noise models. Extrapolating the temperature trends for each geometry shows that it is possible that the noise observed in the transverse samples has the same origin as the higher frequency part of the double power law spectra observed in the longitudinal samples.Conference Object Citation - WoS: 76Citation - Scopus: 80Stability of Microcrystalline Silicon for Thin Film Solar Cell Applications(Institute of Electrical Engineers, 2003) Finger, Friedhelm; Carius, Reinhard; Dylla, Thorsten; Klein, Stefan; Okur, Salih; Güneş, MehmetThe development of microcrystalline silicon (μc-Si:H) for solar cells has made good progress with efficiencies better than those of amorphous silicon (a-Si:H) devices. Of particular interest is the absence of light-induced degradation in highly crystalline μc-Si:H. However, the highest efficiencies are obtained with material which may still include a-Si:H regions and light-induced changes may be expected in such material. On the other hand, material of high crystallinity is susceptible to in-diffusion of atmospheric gases which, through adsorption or oxidation, affect the electronic transport. Investigations are presented of such effects concerning the stability of μc-Si:H films and solar cells prepared by plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition.Article Citation - WoS: 15Citation - Scopus: 141/F-noise Study of Undoped Intrinsic Hydrogenated Amorphous Silicon Thin Films(American Physical Society, 1999) Güneş, Mehmet; Johanson, Robert E.; Kasap, Safa O.Conductance fluctuations in four samples of undoped intrinsic hydrogenated amorphous silicon (a-Si:H) were measured in the temperature range of 450 K to 500 K and for frequencies from 2 Hz to 3 kHz. The noise spectra divide into two regions that each fit a 1/fα power law but with different slope parameters α and different temperature dependences. At low frequencies, α is greater than unity and increases with temperature. At high frequencies, α is near 0.6 and temperature independent, but the noise magnitude decreases rapidly with temperature. We infer from the different dependences on temperature that the noise is generated by two independent mechanisms operating simultaneously in a-Si:H. We also observe that the 1/f noise exhibits a quadratic dependence on bias current and Gaussian statistics.