We have designed two CMOS compatible plasmonic electro-absorption modulators (EAMs) based on vanadium dioxide (VO2) and indium tin oxide (ITO). Their performance matrices have been improved in terms of insertion loss (IL), extinction ratio (ER), and figure of merit (FOM). Rigorous Finite Element Method (FEM) has been used to optimize output parameters based on the input device parameters. The IL, ER, and FOM for both the modulators were 0.651 dB/µm, 5.85 dB/µm, 8.98, respectively, for VO2 based EAM and 0.025 dB/µm, 3.07 dB/µm, 122, respectively, for ITO based EAM. This article can be useful to design a CMOS compatible optical modulator on Silicon-on-Insulator (SOI) technology.