Effect of adhesive layers on photocurrent enhancement in near-infrared quantum-dot photodetectors coupled with metal-nanodisk arrays

We fabricated plasmon-enhanced planar Ge/Si quantum dots photodetectors on Silicon-on-insulator substrate coupled with regular array of metallic nanodisks on photodetector surface. It was demonstrated that insertion of supplementary adhesion layers between silicon substrate and noble metal required for stable structure results in suppression of localized surface plasmons resonance. Selection of the Al nanodisks without adhesion layers allows to increase the photodetectors efficiency by about 40 times at wavelength 1.2 $\mu$m and by 15 times at wavelength 1.55 $\mu$m.