Reducing contact resistivity in Ge-rich SiGe modulators for optical interconnects

This thesis discusses reducing contact resistivity in Ge-like SiGe modulators through two methods: Dopant segregation and Metal-Insulator-Semiconductor (MIS) approach. We first discuss the challenges associated with implementing the dopant segregation technique because of the requirement of a high temperature anneal step.
We then discuss the techniques that were used to fabricate the MIS based SiGe modulators that used TiO2 as the insulator layer. Using this technique, we managed to almost completely depin the Fermi level and reduce the contact resistivity by 25x and two orders of magnitude.