Manifestation of “slow” light in the photocurrent spectra of Ge/Si quantum dot layers combined with a photonic crystal

The spectral characteristics of the photocurrent in the near-infrared range in vertical Ge/Si $p-i-n$ photodiodes with Ge quantum dots embedded in a two-dimensional photonic crystal are investigated. The interaction of the quantum dots with photonic Bloch modes leads to the resonant enhancement of the sensitivity of photodiodes. The dependences of the photocurrent on the angle of incidence of light are used to determine the dispersion relations of the Bloch modes. Regions in the dispersion characteristics where the group velocity of photons is close to zero are revealed. It is established that the maximum enhancement of the photocurrent relative to a photodiode without photonic crystal, which can be up to a factor of $\sim$ 60, results from the interaction of quantum dots with “slow” Bloch modes.