Temperature dependent electrical and dielectric properties of a metal/Dy2O3/n-GaAs (MOS) structure

Abstract

This paper describes the structural properties, electrical and dielectric characteristics of thin Dy2O3 layer deposited on the n-GaAs substrate by electron beam deposition under ultra vacuum. Structural and morphological characterizations are investigated by atomic force microscopy (AFM) and X-ray diffraction measurements (XRD). The XRD shows that the elaborated Dy2O3 oxide has a cubic structure. The electrical and dielectric properties of Co/Au/Dy2O3/n-GaAs structure were studied in the temperature range of 80–500K. The conductance and capacitance measurements were performed as a function of bias voltage and frequency. The dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tanδ) of the structure are obtained from capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. These parameters are found to be strong functions of temperature and bias voltage. A strong negative capacitance (NC) phenomenon has been observed in C–V; hence ε′–V plots for each temperature value take negative values. The following behavior of the C and ε′ in the forward bias region has been explained with the minority-carrier injection and relaxation theory. From DC conductance study, electronic conduction is found to be dominated by thermally activated hopping at high temperature. Activation energy is deduced from the variation of conductance with temperature. The interface state density (Nss) of the structure is of the order 1.13×1013eV−1cm−2.