Modulation Mechanism of Absorption Layer Doping Concentration and Electrode Configuration on Optoelectronic Properties of Sub-Pixel Lattice-Matched InGaAs SWIR Photodetectors

Large dark currents currently limit the performance of InGaAs short-wave infrared (SWIR) detectors in aerospace remote sensing and night vision applications. To address this issue, SWIR detectors featuring various absorption layer doping concentrations and bilateral electrode configurations were fabricated on lattice-matched NIN InP/InGaAs/InP double heterojunctions via metal-organic chemical vapor deposition (MOCVD). Experimental and TCAD two-dimensional simulations demonstrate that increasing the absorption layer doping is the dominant factor, significantly reducing the total dark current density by ~96%. Mechanistic analysis indicates that increased doping in the absorption layer narrows the depletion region and prolongs the minority carrier lifetime, effectively suppressing both generation-recombination and trap-assisted tunneling currents. Concurrently, the bilateral electrode design distributes the electric field more uniformly, providing a further reduction in overall leakage. Furthermore, spectral analysis reveals that doping-modulated built-in electric fields lead to differentiated carrier collection mechanisms across varying wavelength bands. Ultimately, the optimized device achieves a peak detectivity of 2.28 × 1012 cm·Hz1/2W-1, representing an 82% improvement over low-doped counterparts and providing a crucial theoretical basis for the design of high-performance InGaAs detectors.