title: Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure.
abstract: A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO(2) matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.
authors.affiliation: Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan.
authors.forename: Mohd Fairuz
authors.initials: MF
authors.lastname: Budiman
authors.forename: Weiguo
authors.initials: W
authors.lastname: Hu
authors.forename: Makoto
authors.initials: M
authors.lastname: Igarashi
authors.forename: Rikako
authors.initials: R
authors.lastname: Tsukamoto
authors.forename: Taiga
authors.initials: T
authors.lastname: Isoda
authors.forename: Kohei M
authors.initials: KM
authors.lastname: Itoh
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yamashita
authors.forename: Akihiro
authors.initials: A
authors.lastname: Murayama
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Okada
authors.forename: Seiji
authors.initials: S
authors.lastname: Samukawa