Current transport in Ni Schottky barrier on GaN epilayer grown on free standing substrates

In this paper, the Ni Schottky barrier on GaN epilayer grown free standing substrates has been characterized. First, transmission electrical microscopy (TEM) images and nanoscale analysis by conductive atomic force (C-AFM) of bare material allowed visualizing structural defects in crystal, as well local inhomogeneities current conduction. The forward current-voltage (I-V) characteristics Ni/GaN vertical diodes fabricated gave average values height 0.79 eV ideality factor 1.14. A statistical over a set diodes, combined with temperature dependence measurements, confirmed formation an inhomogeneous material. From plot ΦB versus n, ideal homogeneous close to 0.9 was estimated, similar that extrapolated capacitance-voltage (CV) analysis. Local I-V curves, acquired means C-AFM, displayed distribution onset conduction, which turn resembles one observed macroscopic diodes. Finally, reverse characteristic defects-free region have at different its behaviour described thermionic field emission (TFE) model.