The use of GaN as an alternative interlayer for stable passivation of gallium arsenide surface is investigated. To this aim remote N-2-H-2 plasma nitridation of the n-doped gallium arsenide surface has been performed. The exposure time to N-2-H-2 plasmas has been varied in order to form ultrathin GaN layers with different thickness. Gallium nitride layer thickness and composition analysis have been determined by in situ spectroscopic ellipsometry. The changes of the electronic properties of GaAs surface induced by nitridation process have been studied by means of DC and AC electrical characterizations on Schottky barrier diodes tailored on gallium nitride/gallium arsenide structure. The evidence of achievement of GaAs surface electronic passivation under short time plasma treatment will be provided. (C) 2004 Elsevier Ltd. All rights reserved.