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

Abstract

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 Ion/Ioff ratio up to 106. A relatively high effective electron barrier height for NiGe/n-Ge has been achieved by the BF2+ 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 °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.