Flow of the current along metallic shunts in ohmic contacts to wide-gap III–V semiconductors

Abstract

It is established experimentally that the contact metal—wide-gap semiconductor (GaAs, GaP, GaN) with the Schottky barrier transforms into the ohmic contact either in the process of continuous heating or in the process of holding at an elevated temperature before the formation of any recrystallized layers. In this case, resistance of the contact reduced to the unit area increases as the temperature increases for semiconductors with a high dislocation density (GaP, GaN). It is assumed that in such contacts, the current flows along the metallic shunts, which shorten the layer of space charge and are formed by metal atoms diffused along the dislocation lines or other imperfections of the semiconductor. In semiconductors with a low dislocation density (GaAs), resistance of the ohmic contact per unit area decreases with increasing the temperature as it was expected for the thermionic mechanism of current flowing.