Physics of Metal/High-k Interfaces

The conventional theory of work functions (Schottky barriers) does not work at pure-metal/high-k-dielectrics interfaces. This occurs due to the selective interface atom bonding reflecting the large ionicity of high-k materials and the characteristic density of p-metal electronic states. Taking into accounts these features, we have constructed a new theory of work functions based on a concept of generalized charge neutrality levels. This theory systematically explains work functions of various gate materials on high-k dielectrics, in particular the unusual behavior of p-metal work functions, and naturally reproduces band offsets at various semiconductor/semiconductor interfaces.