Current–voltage characteristics of Au/GaN/GaAs structure

Abstract

Au/GaN/n-GaAs structure has been fabricated by the electrochemically anodic nitridation method for providing an evidence of achievement of stable electronic passivation of n-doped GaAs surface. The change of the electronic properties of the GaAs surface induced by the nitridation process has been studied by means of current–voltage ( I–V) characterizations on Schottky barrier diodes (SBDs) shaped on gallium nitride/gallium arsenide structure. Au/GaN/n-GaAs Schottky diode that showed rectifying behavior with an ideality factor value of 2.06 and barrier height value of 0.73 eV obeys a metal–interfacial layer–semiconductor (MIS) configuration rather than an ideal Schottky diode due to the existence of GaN at the Au/GaAs interfacial layer. The formation of the GaN interfacial layer for the stable passivation of gallium arsenide surface is investigated through calculation of the interface state density N ss with and without taking into account the series resistance R s. While the interface state density calculated without taking into account R s has increased exponentially with bias from 2.2×10 12 cm −2 eV −1 in ( E c−0.48) eV to 3.85×10 12 cm −2 eV −1 in ( E c−0.32) eV of n-GaAs, the N ss obtained taking into account the series resistance has remained constant with a value of 2.2×10 12 cm −2 eV −1 in the same interval. This has been attributed to the passivation of the n-doped GaAs surface with the formation of the GaN interfacial layer.