Mid-infrared plasmonic silicon quantum dot/HgCdTe photodetector with ultrahigh specific detectivity

Highly sensitive photodetectors operating at mid-infrared (MIR) wavelengths are urgently required for the applications of astronomy, optical communication, security monitoring, and so forth. However, further promoting the sensitivity in conventional MIR devices for a higher detectivity is challenging. Among the potential strategies, integrating localized surface plasmon resonance with MIR semiconductors is a promising approach to developing high-performance optoelectronics. Here we demonstrate a high-sensitivity boron (B)-doped silicon quantum dot (Si-QD)/HgCdTe (MCT) MIR photodetector. Because of plasmon-induced hot-hole tunneling and enhanced light absorption, the hybrid photodetector exhibits a high specific detectivity of ∼1.6 × 109 cm·Hz1/2·W−1 (Jones) and a high-speed response (∼224 ns for the rise time and ∼580 ns for the fall time) at room temperature. Furthermore, the device achieves high-performance spectral blackbody detection with a peak detectivity of up to 1.6×1011 Jones at ∼5.8 µm under a cryogenic environment of 77 K, higher than that of bare MCT. This prominent enhancement can be attributed to the further suppression of hot-hole cooling due to a reduced phonon population at low temperatures, which facilitates more efficient hot-carrier extraction and contributes to ultrahigh sensitivity. The plasmonic material-integrated MCT architecture can pave the way for developing high-performance MIR photodetection.