Tuning of the Schottky barrier height in NiGe/n-Ge using ion-implantation after germanidation technique

In this paper, a method of ion-implantation after germanidation (IAG) has been presented to modulate the Schottky barrier (SB) heights on germanium substrates. Schottky diodes have been fabricated with improved rectifying current curves and larger ${\text{I}}_{\text{on}}/{\text{I}}_{\text{off}}$ ratio up to ${10}^6$ . A relatively high effective electron barrier height for $\text{NiGe}/n\text{-Ge}$ has been achieved by the ${\text{BF}}_2^{+}$ IAG technique, which suggests a record-low effective hole barrier height of nearly 0.06 eV. The tuning of SB height can be mainly contributed to the effects of fluorine. In addition, there is a process temperature window between 350 to $450°\text{C}$ for the drive-in annealing of IAG to obtain optimized SB heights. These results provide the design guidelines for the process integration of germanium based Schottky barrier source/drain metal-oxide-semiconductor field-effect transistors.