Proof of concept for IR-SOIPIX, a monolithic midinfrared image sensor fabricated using a standard CMOS process

Abstract

IR-SOIPIX is a monolithic mid-infrared (MIR) image sensor developed using a standard CMOS process on a silicon-on-insulator wafer. Unlike conventional hybrid detectors that require indium bump bonding, IR-SOIPIX integrates the detector and readout circuitry in a single chip, reducing manufacturing complexity and cost. Cryogenic tests (∼ 4 K) on a single-element test device confirmed key features: dark current suppression using a blocking layer, identification of impurity-related activation energies, and results consistent with photon detection at wavelengths of up to ∼ 30 μm. The initial prototype demonstrated a quantum efficiency of approximately 0.8%, and further optimization of impurity concentration and layer thickness is expected to improve this by up to an order of magnitude based on scaling of absorption probability with impurity concentration and active-layer thickness. These results establish the feasibility of scalable, low-cost and high-performance MIR sensors for next-generation astronomical missions.