title: High-performance infrared light trapping in nano-needle structured p⁺ SnOx (x  ≤  1)/thin film n-Ge photodiodes on Si.
abstract: We report nano-needle structured conductive SnOx (x≤1) as a self-assembled electrode for high-efficiency light trapping in thin-film infrared (IR) photonic devices, benefiting from the high scattering efficiency, high density, and low IR loss of the nano-needles. We demonstrate a 2.2× responsivity enhancement for a 1.5-μm-thick Ge absorber in a nano-needled p(+) SnOx/n-Ge photodiode on Si at λ=1580  nm, in good agreement with theoretical calculation of 2.3× enhancement assuming no IR loss in the nano-needles. Such low-loss light trapping can potentially enable 15-30× absorption enhancement at λ=1600-1650  nm in the Ge layer when integrated with a perfect rear reflector.
authors.forename: Xiaoxin
authors.initials: X
authors.lastname: Wang
authors.forename: Andrew
authors.initials: A
authors.lastname: Wong
authors.forename: Stephanie
authors.initials: S
authors.lastname: Malek
authors.forename: Yan
authors.initials: Y
authors.lastname: Cai
authors.forename: Jifeng
authors.initials: J
authors.lastname: Liu