Research Article

Numerical modeling of InGaAs/AlGaAs heterostructure for short-wave infrared nBn photodetectors

¹ Nanotechnology Research Center, Bilkent University, 06800 Ankara, Turkey
² Department of Physics Engineering, Ankara University, 06560 Ankara, Turkey
³ Department of Physics, Bilkent University, 06800 Ankara, Turkey
⁴ Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara, Turkey
⁵ Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara 06560, Turkey

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 29 December 2026
Accepted: 8 April 2026

Abstract

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.