SPM electrical characterization of Ti/Al — Based ohmic contacts for sub-micron devices

The electrical properties of Ti/Al-based ohmic contacts with two types of barrier films, Ti and Mo, are investigated in dependence on the Ti/Al ratio and the type of the barrier layer. They are explored by I-V, resistivity and surface potential measurements. It is found out that the Ti/Al/Ti/Au contact composition with Ti/Al ratio of 0.43 exhibits the lowest contact resistivity and smallest variations of the surface potential amplitude. The contacts with the same Ti/Al ratio and a Mo barrier layer show better surface morphology but poorer electrical properties.