Midinfrared Plasmon-Enhanced Spectroscopy with Germanium Antennas on Silicon Substrates

Midinfrared plasmonic sensing allows the direct targeting ofunique vibrationalfingerprints of molecules. While gold has been usedalmost exclusively so far, recent research has focused on semiconductorswith the potential to revolutionize plasmonic devices. We fabricate antennasout of heavily doped Gefilms epitaxially grown on Si wafers anddemonstrate up to 2 orders of magnitude signal enhancement for themolecules located in the antenna hot spots compared to those located on abare silicon substrate. Our results set a new path toward integration ofplasmonic sensors with the ubiquitous CMOS platform