title: Design of multifold Ge/Si/Ge composite quantum-dot heterostructures for visible to near-infrared photodetection.
abstract: We demonstrate an effective approach to grow high-quality thin film (>1  μm) of multifold Ge/Si/Ge composite quantum dots (CQDs) stacked heterostructures for near infrared photodetection and optical interconnect applications. An otherwise random, self-assembly of variable-fold Ge/Si CQDs has been grown on Si through the insertion of Si spacer layers to produce micron-scale-thick, stacked Ge/Si CQD layers with desired QD morphology and composition distribution. The high crystalline quality of these multifold Ge CQD heterostructures is evidenced by low dark current density of 3.68  pA/μm2, superior photoresponsivity of 267 and 220 mA/W under 850 and 980 nm illumination, respectively, and very fast temporal response time of 0.24 ns measured on the Ge/Si CQD photodetectors.
authors.forename: Ming-Hao
authors.initials: MH
authors.lastname: Kuo
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Lai
authors.forename: Sheng-Wei
authors.initials: SW
authors.lastname: Lee
authors.forename: Yen-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Chang
authors.forename: Wen-Hao
authors.initials: WH
authors.lastname: Chang
authors.forename: Tzu-Min
authors.initials: TM
authors.lastname: Hsu
authors.forename: Pei-Wen
authors.initials: PW
authors.lastname: Li