Method of manufacturing low resistivity contacts on n-type germanium

An electrical contact comprising:

• a germanium region consisting of germanium doped with n-type dopants at a first doping level;
• an epitaxially grown interfacial silicon layer on the germanium region, wherein the epitaxially grown interfacial silicon layer is doped with n-type dopants at a second doping level that remain confined within the epitaxially grown interfacial silicon layer, wherein the second doping level is at least 1×1019 cm−3, thereby overcoming Fermi-level pinning and dopant activation limitation in the germanium region, and wherein the epitaxially grown interfacial silicon layer has a thickness between five monolayers and 50 nm and is at least partially relaxed;
• and
• a layer of material overlying the epitaxially grown interfacial silicon layer and having an electrical resistivity smaller than 1×10−2 Ωcm,
• wherein the electrical contact is formed between the germanium region and the layer of material, and wherein the electrical contact has a specific contact resistivity below 10−4 Ωcm2.

An electrical contact comprising:

• a germanium region consisting of germanium doped with n-type dopants at a first doping level;
• an epitaxially grown interfacial silicon layer on the germanium region, wherein the epitaxially grown interfacial silicon layer is doped with n-type dopants at a second doping level that is at least 1×1019 cm−3, thereby overcoming Fermi-level pinning and dopant activation limitation in the germanium region, and wherein the epitaxially grown interfacial silicon layer has a thickness between five monolayers and 50 nm and is at least partially relaxed;
• and
• a layer of material overlying the epitaxially grown interfacial silicon layer and having an electrical resistivity smaller than 1×10−2 Ωcm,
• wherein the electrical contact is formed between the germanium region and the layer of material, and wherein the electrical contact has a specific contact resistivity below 10−4 Ωcm2.