Ohmic contact formation on n-type Ge

Severe Fermi level pinning at the interface between n-Ge and a metal, leads to the formation of a Schottky barrier, almost independent on the metal work function. Therefore it seems impossible to form metal Ohmic contacts on moderately, n-type doped Ge layers. For p-type Ge the Fermi level pinning works opposite: all metal contacts show Ohmic behavior. This fixed behavior can be altered by the introduction of a thin Ge3N4 layer. Ge3N4 seems effective in reducing Fermi level pinning and therefore allows the formation of Ohmic contacts on n-type Ge and a rectifying contact on p-type Ge.