Broadband very long wavelength infrared focal plane array based on phosphorus-doped silicon blocked impurity band

Abstract

Very long wavelength infrared (VLWIR, 14–30 μm) detection is crucial for observing low-temperature objects, such as those in infrared astronomy and Earth remote sensing, where focal plane arrays (FPAs) with ultra-low dark current and broadband spectral response are essential. Silicon-based blocked impurity band (BIB) photodetectors are promising candidates due to their intrinsically low dark current and sensitivity in the VLWIR range. However, simultaneously achieving a broad spectral response from 14 to 30 μm and high pixel-to-pixel uniformity remains a significant challenge. In this work, we report a broadband VLWIR FPA based on phosphorus-doped silicon (Si:P) BIB photodetectors. We designed a Si:P BIB architecture and a readout integrated circuit optimized for deep cryogenic operation. As a result, we developed a 16 × 16 prototype FPA with a 50% cutoff wavelength extended to 32.2 μm. Operating at 4 K, the array exhibits a peak detectivity of ∼1 × 1011 cm Hz1/2·W−1 and a dark current below 40 fA. This work provides a solution for future broadband VLWIR detection on both space-based and ground-based platforms.