Electrical Characterization of Interface States at Schottky Contacts and MIS Tunnel Diodes

Abstract

Schottky1 ascribed the barrier ∑ = φm-x at rectifying metal/semiconductor contacts to the difference between the work function φmof the metal and the electron affinity xof the semiconductor. Bardeen explained deviations from this model by charged states within the band gap of the semiconductor.2 Since that time, the characterization and description of interface states has become a major task for the understanding of Schottky barrier formation. These states are thought to originate either from intrinsic semiconductor surface states,1 metal-induced gap states,3–5 defects induced by metal deposition,6 interface dislocations,7 or a combination of these effects. Deviations from the Schottky model2 are then understandable on the basis of trapped interface charge which maintains a dipole at the interface between the metal and the semiconductor.8