Impact of Yb, In, Ag and Au Thin Film Substrates on the Crystalline Nature, Schottky Barrier Formation and Microwave Trapping Properties of Bi<sub>2</Sub>o<sub>3< Films

Abstract

The effect of the Yb, In, Ag and Au thin film metal substrates on the structural and electrical properties of Bi2O3 thin films are investigated by means of X-ray diffraction, impedance spectroscopy an current-voltage characteristic techniques. The Bi2O3 films are observed to exhibit a crystallization nature depending on the crystal structure of the substrate. Particularly, when the metal substrate is facing centered cubic, the Bi2O3 prefers the gamma-phase of body centered cubic crystallization for the (Yb, Ag and Au)/Bi2O3 interfaces. Whereas when a tetragonal substrate (indium) is used, the tetragonal beta-Bi2O3 single phase is preferred. All structural parameters presented by the lattice constant, degree of orientation, dislocation density, micro-strain and grain size are observed to strongly depend on the crystal type. In addition, the evaluation of the Schottky barrier formation at the (Yb, In, Ag, Au)/Bi2O3/Au interfaces by the current-voltage characteristics, revealed that the (In, Au)/Bi2O3/Au interface exhibit ohmic nature of contact and the (Yb,Ag)/Bi2O3/Au are of Schottky type, the rectification ratio for the Yb/Bi2O3/Au interface reaches a value of 10(5) indicating the applicability of these interfaces in CMOS digital logic devices. Moreover, the impedance spectroscopy analysis revealed that the ohmic interfaces exhibit a negative capacitance effect. The In/beta-Bi2O3/Au and Yb/.-Bi2O3/Au interfaces are performing as microwave traps with wave absorption percentage of 62% and 92% at frequencies of 193 and 1200 MHz, respectively. The features of the devices are promising as they indicate the applicability as microwave resonator and fast electronic switches.