Physics of Metal/Ge Interfaces; Interface Defects and Fermi-level Depinning

摘要

Defect distribution and Fermi-level depinning at metal/Ge interfaces are studied based on the first-principles calculations. It is shown that metal induced gap states (MIGS) hybridize with defect electronic states and work to increase interface disorders. In addition, we show that Fermi-level pinning (FLP) is caused not only by MIGS but also by disorder induced gap states (DIGS), while the GeO_2 and α-Sn interface layers block the MIGS penetration into Ge layers and break the FLP. The effects of dopant segregation and germanide/silicide metal electrodes on FL depinning are also discussed.