Role of an interlayer at a TiN/Ge contact to alleviate the intrinsic Fermi-level pinning position toward the conduction band edge

TiN/Ge contacts, prepared by direct sputter deposition from a TiN target, can alleviate the intrinsic Fermi-level pinning (FLP) position toward the conduction band edge. This work focuses on studying the origin of the FLP alleviation. Investigations on both the electrical properties and interfacial structures of TiN/Ge contacts showed that an amorphous interlayer (IL) containing nitrogen played an important role in the alleviation. For comparison, the properties of Ti/Ge contacts were also studied. Based on these results, the IL structure that induced the FLP alleviation was clearly shown and a model was proposed to explain the FLP alleviation. (C) 2014 AIP Publishing LLC.