Surface plasmons on PtSi for visible and infrared Schottky-barrier-enhanced detection

Excitation of surface plasmons by attenuated total reflection is used to optically characterize platinum silicide films and to produce enhanced photosignals from PtSi-Si Schottky barrier devices. In this work the Otto configuration (prism-air gap-sample) for attenuated total reflection is used to excite the mode at the air-PtSi interface on PtSi-Si structures; surface plasmon excitation is evidenced as a prominent dip in measurement of reflectance as a function of internal angle of incidence in the prism. Coupling efficiencies of 90 - 95% between incoming p-polarized radiation and surface plasmons on PtSi have been achieved at wavelengths ranging from the visible to the infrared (0.633 μm to 3.39 μm). The surface plasmon energy is dissipated by absorption through the creation of electron-hole pairs in the lossy silicide layer. Subsequent hot carrier emission over the Schottky barrier can thus yield an enhanced photosignal associated with the enhanced absorption due to surface plasmon excitation - initial results demonstrating this phenomenon are reported. here. Finally, reflectivity calculations show also the possibility of infrared surface plasmon excitation in PtSi grating structures with periodicity of the same order as the wavelength.