Gourd-shaped hole array germanium (Ge)-on-insulator photodiodes with improved responsivity and specific detectivity at 1,550 nm

• Main Authors: Son, Bongkwon, Zhou, Hao, Lin, Yiding, Lee, Kwang Hong, Tan, Chuan Seng
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Electrical and electronic engineering::Semiconductors; Germanium; Photodetector
• Online Access: https://hdl.handle.net/10356/148841
• Institution: Nanyang Technological University

Gourd-shaped hole array germanium (Ge) vertical p-i-n photodiodes on a germanium-on-insulator (GOI) substrate were designed and demonstrated with excellent responsivity and specific detectivity of 0.74 A/W and 3.1 × 10^10 cm·Hz^1/2/W, respectively, at the wavelength of 1,550 nm. The responsivity is enhanced by ~2.5×, and the specific detectivity is superior to that of commercial bulk Ge photodiodes. It is determined that the gourd-shaped hole array design provides a higher optical absorption compared to a cylinder-shaped hole array design. The external quantum efficiency for the gourd-shaped hole array photodetector was enhanced by ~250% at 1,550 nm wavelength at -1 V, comparing with hole-free array photodetectors. The 3-dB bandwidth for the hole array photodetectors is improved by ~10% due to a lower device capacitance. This work paves the way for low-cost and high-performance CMOS compatible photodetectors for Si-based photonic-integrated circuits.