Photocurrent enhancement in silicon photodiodes with Ge quantum dots by hybrid plasmonic and dielectric modes of a planar waveguide

The spectral characteristics of the near-infrared photocurrent in vertical Ge/Si photodiodes with Ge quantum dots embedded in a planar waveguide and coupled with a plasmonic structure on the surface of the photodiode are studied. A two-dimensional regular lattice of circular holes in an aluminum film acted as a plasma metasurface, allowing the conversion of external electromagnetic radiation into surface plasmon modes at the Al–Si boundary. The diameter of the holes is 300 nm, the period is 600 nm. In the wavelength range of $\sim$2 $\mu$m, a series of optical resonances was detected, leading to a multiple amplification of the photocurrent compared with samples without perforated Al film. It is established that the maximum amplification of the photocurrent (up to 8 times) is provided by hybrid waves, which are a superposition of plasmonic and dielectric waveguide modes.