Microstructure of vanadium-based contacts on n-type GaN

Atomic force microscopy, wavelength-dispersive x-ray spectroscopy and photoemission electron microscopy were used to study the contact formation of Au/V/Al/V-based contacts on n-type GaN. After a rapid thermal annealing contact formation step, we find that the surface is composed of dendritic structures. The dendrites are Au-rich, while the voids between the branches of the dendrites are V-rich, and cracks in the voids are Ga-rich. A detailed model of the chemical structure and morphology of V-based contacts on n-GaN is given and discussed in view of the ohmic-like behaviour of such contacts.