Formation of ultra-shallow Ohmic contacts on n-Ge by Sb delta-doping

ABSTRACTWe demonstrate low-resistivity Ohmic contacts for n-Ge with ultra-shallow junction. Using the impurity δ-doping techniques with Ge homoepitaxy on Ge(111) below 400 ºC, we can achieve a very abrupt doping profile within a nanometer-scale width. By introducing the δ-doping to atomically controlled metal/Ge contacts, the current-voltage characteristics clearly show Ohmic conductions owing to the effective tunneling through the Schottky barrier. This approach is promising for a formation technology of ultra-shallow source/drain contacts for scaled Ge devices.