Design and characterization of WO3/Li/WOs heterojunction devices رسالة ماجستير

Abstract

In this thesis, we targeted exploring the effects of lithium nano sheet on the structural and electrical properties of WO films. The WoOs films which are coated by the thermal evaporation technique under a vacuum pressure of l10° mbar are highly influenced by the Li nano sheet. Namely, Insertion of Li nano sheets of thicknesses of 50 and 100 nm resulted in metal induced crystallization process. Two structural phases evaluated because of Li nano sheet sandwiching. The induced crystallization process is owed to the large lattice mismatch between films and substrates and films and nano sheets. In addition, the electrical investigation which were carried out by the impedance spectroscopy technique have shown that; stacked layers of tungsten oxide comprising Li nano sheets can perform as microwave resonators. Resonance anti-resonance phenomena is observed in the samples. Moreover, the capacitance spectra which we studied in the frequency domain of 0.01-1.8 GHz have shown the dominants of negative capacitance effect. This effect is beneficial for parasitic capacitance cancellation and noise reduction in electronic circuits. Furthermore, the WO3/Li/WO3 device seems to be used in

application as thin film MOSFET that can be used digital and analog circuits.