Monolithic PbSe/Ge/Si Heteroepitaxial Architecture for Uncooled Dual-Band Infrared Detection

Limitations in heteroepitaxial growth and material property modulation present a formidable challenge for the development of near-infrared-midwave infrared (NIR-MIR) dual-band uncooled detectors capable of operating in both quantum communication and thermal analysis applications. Leveraging our proposed substrate surface selenization technique, we demonstrate a PbSe/Ge/Si heterostructure enabling response at NIR and MIR. The device achieves a room-temperature responsivity of 0.43 A·W^-1 at 2700 nm and 0.7 A·W^-1 at 1550 nm under laser illumination. Blackbody testing reveals peak detectivities (D*) of 4.2 × 10⁹ cm·Hz^1/2·W^-1 at 3.7 μm and 3.5 × 10⁹ cm·Hz^1/2·W^-1 at 1.2 μm. Additionally, the theoretically optimized structure shows that a back-to-back n-i-p-i-n architecture could elevate D* to 2.0 × 10¹⁰ cm·Hz^1/2·W^-1 and 9.8 × 10¹⁰ cm·Hz^1/2·W^-1 at MIR and NIR, respectively. This architecture represents a promising step toward compact multispectral systems with room-temperature dual-band sensitivity, which are of interest for field-deployable quantum communication terminals and portable thermal analytics.