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

• DOI: 10.1364/oe.422931
• Publication Date: 2021-05-08T08:00:43Z
• Authors: Bongkwon Son; Hao Zhou; Yiding Lin; Kwang Hong Lee; Chuan Seng Tan
• Keywords: Photodiode; Specific detectivity; Quantum Efficiency

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