Monolithic photon-trapping Si detector for high-efficiency ultra-broadband infrared detection.

The difficulty of growing high-quality infrared-sensitive materials and their heterogeneous integration with silicon circuits has long been a key factor hindering the development of infrared detectors. In this work, we report a broadband infrared detector fabricated directly on an SOI substrate through arsenic doping. The optical absorption efficiency in the absorption region (AR) is greatly enhanced through a sophisticated photo-trapping structure design, leading to a significant improvement in quantum efficiency over the entire response range. The fabricated photo-trapping SOI:As detectors exhibit average enhancement of 346% for external quantum efficiency (EQE) and 696% for internal quantum efficiency (IQE) across the 7-22 μm range. The EQE and the IQE at the peak wavelength reach 20% and 40% with an extremely thin AR ( 100 nm). This CMOS-compatible hybrid architecture provides a promising pathway toward high-performance and large-scale monolithic infrared detector arrays.