Bias-Tunable Broadband Infrared Heterostructure Quantum Ratchet Photodetector

Abstract

The development of a photon-type very long-wavelength infrared (VLWIR) detector that simultaneously achieves broadband spectral response and elevated operating temperatures remains a formidable challenge. GaAs/AlGaAs quantum ratchet structures have emerged as a promising architecture to circumvent conventional semiconductor bandgap limitations, enabling multispectral detection while effectively suppressing dark current. In this work, metal-organic chemical vapor deposition (MOCVD)-grown GaAs/AlGaAs heterojunction quantum ratchet photodetectors (QRPDs) are demonstrated. Theoretical and experimental studies of the system were conducted to investigate its spectral response and transport properties. The multiperiod quantum ratchet structure exhibits broadband detection covering the near-infrared to very long-wavelength infrared bands. The asymmetric low-dimensional quantum structure also leads to a photovoltaic-like effect with zero bias response and bias-tuned spectral characteristics. A high peak specific detectivity of 2.4 × 10¹¹ cm·Hz^1/2 W^–1 was achieved at zero bias. Thanks to the suppression of dark current by the ratchet barrier, the BLIP temperature of the QRPD reached 40 K. This work not only demonstrates the significant potential of quantum ratchet devices for broadband high-temperature operation but also verifies the feasibility of MOCVD in the mass production of quantum ratchet devices, offering a promising solution for cost-effective product iteration and broader application scenarios in photon-type infrared detection.