Physical and electrical characteristics of metal/Dy2O 3/p-GaAs structure

Abstract

This paper describes the effect of post-deposition annealing on the physical and electrical characteristics of high-k Dy2O3 dielectric films deposited at 250 °C on p-GaAs substrate by electron beam deposition under ultra vacuum. The morphological and structural features of Dy2O3 layer before and after postdeposition annealing were studied by atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface topography analysis reveals that the Dy2O3 film is granular, and contains numerous contacts between columnar grains. While investigating the electrical properties Dy2O3 oxide, the current-voltage characteristics I(V) suggest a Poole-Frenkel (PF) type mechanism of carrier transport for as-deposited and annealed layers. A deviation from the PF leakage current course was found and attributed to the current carrier trapping. The ac impedance properties of the structures have been studied in a wide frequency range at different bias voltage. The Dy2O3 annealed exhibited excellent electrical properties such as small density of interface state and low leakage current. This phenomenon is attributed to a rather crystallized Dy2O3 structure and the reduction of the defects at the oxide/GaAs interface. © 2014 Elsevier B.V.