Numerical Modeling of InGaAs/AlGaAs Heterostructure for Short-Wave Infrared nBn Photodetectors

nBn infrared photodetectors have emerged as a strong alternative to conventional pn and pin-based structures due to their low dark current, fast response, and suppression of Shockley–Read–Hall (SRH) generation pathways. In this study, an InP-based InGaAs/AlGaAs/InGaAs nBn heterostructure was designed and numerically analyzed using SILVACO TCAD at 300 K to investigate its electro-optical behavior under various bias conditions. The effects of barrier thickness and band alignment engineering were systematically evaluated with a particular focus on minimizing the effective valence band offset and blocking majority-carrier leakage without hindering photocarrier transport. The simulated band diagrams confirm that the AlGaAs barrier layer enables efficient majority-carrier suppression while maintaining low-resistance conduction paths for photogenerated carriers. As a result, the proposed device exhibits low dark current and high responsivity performance comparable to planar InGaAs structures even under low bias operation. These results highlight the significance of optimized barrier design in achieving high detectivity without relying on complex fabrication routes. Overall, the presented findings demonstrate the potential of tailored nBn architectures for next-generation short-wave infrared imaging, low-photon-flux sensing, and high-dynamic-range optoelectronic systems.