Plasmonic materials for metal–insulator–semiconductor–insulator–metal nanoplasmonic waveguides on silicon-on-insulator platform

• Investigate three metals and two dielectrics in MISIM plasmonic waveguides.
• Shows dramatic effect of fabrication process of materials on waveguide properties.
• Comparison of experimental and theoretical results for waveguide properties.
• Use of Cr adhesion layer is shown to greatly increase losses for Au clad waveguides.
• Propagation length of 7.25 μm found for Au/SiO2 MISIM plasmonic waveguides.

The use of various plasmonic metals and insulators in silicon based metal–insulator–semiconductor–insulator–metal (MISIM) nanoplasmonic waveguides are investigated for use in waveguiding applications at 1.55 μm. Sputtered Au, Ag, and Cu as the metal cladding with thermally grown SiO2 and ALD grown HfO2 insulating dielectric spacer layers are examined to determine how their fabrication affects the crucial metal–dielectric interface. The experimental propagation lengths and coupling efficiencies to silicon-on-insulator waveguides are compared to theoretical values, with the Au/SiO2 MISIM nanoplasmonic waveguide showing a propagation length of 7.25 μm. The effect of including an adhesion layer for Au is shown to significantly increase losses.