Preparation and Characterization of AgO-As:03 Thin films رسالة ماجستير

Abstract

In this thesis, stack layers of oxidized silver and arsenic oxide are fabricated by the thermal evaporation technique under a vacuum pressure of 10 mbar. Two classes of the films were grown. One is thin (100 nm each sample( and other is thick )1.0 m( of Ag)O(As)O). The films are characterized by X-ray diffraction , optical spectrophotometer and impedance spectroscopy techniques, respectively. It was observed that Ag based films are of cubic structure comprising monoclinic AgO as minor phases. The weight of AgO in the films is less than 30%. While the AsO films displayed amorphous nature of structure. The cubic nature of structure is reserved in the Ag(O(/As)O) films. Optically, arsenic oxide films display semiconductor characteristics with energy band gap of 2.41 eV. Coating As oxide onto oxidized Ag films enhanced the light absorbability of As oxide, blue shifts the energy band gap and alters the width of the energy band tails. In addition, the dielectric dispersion in the As oxide films is strongly influenced and decreased in the IR range of light. Modeling of the imaginary part of the dielectric constant using Drude-Lorentz theory allowed determining the optical conductivity parameters. The optical conductivity parameters presented by the drift mobility and Plasmon frequency are suitable for communication technology. The Plasmon frequency reaches 20 GHz which is target in 5G technologies. Electrically, the capacitance-voltage characteristics which were recorded after contacting the films with carbon point contact, revealed metal oxide field effect transistor characteristics. the built in voltage of the device is high enough for the thin film technology. On the other hand, the impedance spectroscopy studies in the frequency domain of 0.01-1.0 GHz

have shown that the device could exhibit negative capacitance effect associated with resonance- antiresonance phenomena in the radio wave and microwave ranges of spectra. These features of

the device make it appropriate for communication technologies.