Fabrication of Low-Resistance Ni Ohmic Contacts on n+-Ge1−xSnx

A highly doped n-type GeSn layer with a doping concentration of approximately 5×10²⁰ cm^-3 was grown successfully by the sputtering epitaxy method. The current- voltage behavior of Ni/n-GeSn under various annealing temperatures was investigated. Both the high doping concentration and the formation of Ni stanogermanide led to the formation of an ohmic contact. The contact resistance was approximately 1.30 × 10^-6 Ω·cm^-2, which is much lower than that reported for Ni/n-GeSn structures. These results suggest that heavy doping is an effective method for obtaining a low contact resistance in n-GeSn technology.