Abstract
This paper describes the structural properties, electrical and dielectric characteristics for the first time of the high-k Dy2O3 oxide film deposited on the porous Si substrate by electron beam deposition under ultra vacuum. Structural and morphological characterizations are investigated by a scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction measurements (XRD). The electrical and dielectric characteristics of the Al/Dy2O3/porous Si heterostructure are studied through current-voltage I (V), capacitance voltage C (V), conductance-and capacitance-frequency dependencies (G (f) and C (1)). Therefore, the dominant conduction mechanisms for the Al/Dy2O3/porous Si heterostructure are extracted from the determining of Schottky coefficient (beta(sc)) and Poole-Frenkel coefficient (beta(pF)). The experimental values of fisc and)beta(pF) coefficients are calculated from I (V) characteristics and compared with theoretical values, thus, the appropriate model has been proposed. The C (V) characteristics at different frequencies revealed a large frequency-dispersion, indicative of a significant density of interface states. Furthermore, the G (f) characteristics were well fitted by the modified law G(AC) (f) = A(1)f(s1) + A2f(s2) and the results showed frequency dependent and evidence of two different behaviors in ac conductance i.e. the low-frequency conductivity is due to long-range ordering (frequency-independent) and high frequency conduction due to the localized orientation hopping mechanism. The Nyquist diagrams are used to identify the equivalent circuit, so, the Al/Dy2O3/porous Si heterostructure is accurately modeled at frequency ranges from 10 Hz to 1000 kHz, as a two parallel elements (RC) network placed in series. (C) 2014 Elsevier Ltd. All rights reserved.