Physical and electrical characteristics of metal/Dy2O3/p-GaAs structure

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.