Optimization of InGaAs/GaAsSb on InP Type-II Superlattice Photodiode for Extended-SWIR: A Comprehensive Study From Simulation to Photodiode Characterization

In recent years, interest in the extended short-wave infrared (eSWIR) band has grown significantly. The current state-of-the-art III–V short-wave infrared detectors are InGaAs photodiodes (PDs) lattice-matched to InP substrates, limited by a cutoff wavelength of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7~\mu $ </tex-math></inline-formula>m. Superlattice-based detectors have the potential to extend detection beyond this limit while offering higher operating temperatures, simplified epitaxial growth, and reduced manufacturing costs compared to II–VI technologies. Such solutions could push the boundaries of short-wave infrared detection and enable new applications in defense, astronomy, and other fields requiring enhanced infrared imaging. In this context, a collaborative effort involving Thales, III–V Lab, and the Marseille Astrophysics Laboratory is exploring a novel approach to extend the SWIR detection range using superlattices. Building on the well-established InGaAs-on-InP technology, a three-layer strain-compensated superlattice structure has been proposed to mitigate limitations such as carrier localization and restricted vertical transport. This article presents recent results demonstrating significant improvements in quantum efficiency (QE) and carrier delocalization, achieving detection performance up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5~\mu $ </tex-math></inline-formula>m. Simulations and experimental characterizations at the PD level were performed to assess the solution’s performance. The study particularly focuses on vertical transport, carrier localization, and minority carrier lifetime, examining their influence on overall imager performance to highlight the benefits and challenges of the proposed eSWIR detector architecture.