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: 2Citation - Scopus: 3The Effects of Oxide Thickness on the Interface and Oxide Properties of Metal-Tantalum Pentoxide-Si (mos) Capacitors(National Institute of Optoelectronics, 2005) Özdağ, Pınar; Atanassova, Elena; Güneş, MehmetHigh dielectric constant tantalum-pentoxide insulating layers were prepared on p-type (100) crystalline silicon wafers using an RF magnetron sputtering technique. Then, metal-oxide-semiconductor (Al-Ta 2O 5-Si) structures were formed with various oxide thickness from 15 to 25 nm. Devices were characterized using the high frequency capacitance-voltage (C-V) spectroscopy method. From the analysis of the high frequency C-V curves, non-ideal effects such as oxide charges and interface trap densities have been evaluated. The results for Ta 2O 5 layers have been compared with those for conventional SiO 2 layers. Interface trap densities were found to be 1.6 ± 0.4×10 12 eV -1 cm -2 for Ta 2O 5 and about 2×10 11 eV -1 cm -2 for SiO 2 insulating layers. There was no clear thickness dependence of the interface trap densities for the Ta 2O 5 insulating layers.Article Citation - WoS: 37Citation - Scopus: 41Differences in the Densities of Charged Defect States and Kinetics of Staebler-Wronski Effect in Undoped (nonintrinsic) Hydrogenated Amorphous Silicon Thin Films(American Institute of Physics, 1997) Güneş, Mehmet; Wronski, Christopher R.A variety of undoped (nonintrinsic) hydrogenated amorphous silicon (a-Si:H) thin films was studied in greater detail using steady-state photoconductivity, σph, subband-gap absorption, α(hν), steady-state photocarrier grating (SSPG), and electron-spin-resonance (ESR) techniques both in the annealed and stabilized light soaked states. The experimental results were self-consisiently modeled using a detailed numerical analysis. It was found that large differences in the optoelectronic properties of device quality a-Si:H thin films can only be explained using a gap slate distribution which consists of positively charged D+ defect states above the Fermi level, the neutral D0 defect states, and the negatively charged D- defect states below the Fermi level. There are large differences both in the densities of neutral and charged defect states and R ratios in different a-Si:H films in the annealed state. The densities of both neutral and charged defect states increased, however, R ratios decreased in the stabilized light soaked state. Very good agreement was obtained between the densities of neutral defect states measured by ESR and those derived from the numerical analysis in the stabilized light soaked state. The kinetics of the Staebler-Wronski effect was also investigated. There was no direct correlation between the decrease of steady-state photoconductivity and increase of subband-gap absorption. The self-consistent fits to wide range of experimental results obtained with the three Gaussian distributions of charged defect states imply that this model is much better representation of the bulk defect states in undoped hydrogenated amorphous silicon thin films.