Surface plasmon enhanced GeSn photodetectors operating at 2 µm

• Published in: Optics express 2021-03, Vol.29 (6), p.8498-8509
• Main Authors: Zhou, Hao, Zhang, Lin, Tong, Jinchao, Wu, Shaoteng, Son, Bongkwon, Chen, Qimiao, Zhang, Dao Hua, Tan, Chuan Seng
• Format: Article
• Language: English
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.420543

Au-hole array and Au-GeSn grating structures were designed and incorporated in GeSn metal-semiconductor-metal (MSM) photodetectors for enhanced photo detection at 2 µm. Both plasmonic structures are beneficial for effective optical confinement near the surface due to surface plasmon resonance (SPR), contributing to an enhanced responsivity. The responsivity enhancement for Au hole-array structure is insensitive to the polarization direction, while the enhancement for Au-GeSn grating structure depends on the polarization direction. The responsivity for GeSn photodetector with Au hole-array structure has ∼50% reinforcement compared with reference photodetector. On the other hand, Au-GeSn grating structure benefits a 3× enhanced responsivity of 0.455 A/W at 1.5V under TM-polarized illumination. The achieved responsivity is among the highest values for GeSn photodetectors operating at 2 µm. The plasmonic GeSn photodetectors in this work offer an alternative solution for high-efficiency photo detection, manifesting their great potentials as candidates for 2 µm optical communication and other emerging applications.