title: Enhanced photocarrier generation in large-scale photonic nanostructures fabricated from vertically aligned quantum dots.
abstract: We demonstrate enhanced photocarrier generation using photonic nanostructures fabricated by a wet etching technique with vertically aligned quantum dots (QDs). Using photoluminescence excitation spectroscopy, we found that the photocarrier generation in Ge/Si QDs placed close to the surface is enhanced below the band gap energy of crystalline silicon. The enhancement is explained by light trapping owing to the photonic nanostructures. Electromagnetic wave simulations indicate that the photonic nanostructure with a subwavelength size will be available to light trapping for efficient photocarrier generation by increasing their dip depth.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tayagaki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hoshi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kishimoto
authors.forename: Noritaka
authors.initials: N
authors.lastname: Usami