Gate-Tunable Graphene-Enhanced Multi-Quantum Well Photodetector for Room-Temperature Mid-Infrared Detection

Abstract

Arash Vaghef-Koodehi

We propose and theoretically analyze a novel graphene-integrated multi-quantum well (MQW) photodetector for mid-infrared (MIR) detection operating at room temperature. The device architecture leverages tunable plasmonic properties of graphene operating near its epsilon-near-zero (ENZ) condition to significantly enhance the intersubband absorption in carefully engineered InGaAs/InAlAs quantum wells. Through electrostatic gating, the graphene Fermi level can be precisely controlled to maximize field enhancement at specific wavelengths across the 3-10 μm MIR range. Our simulations demonstrate a peak responsivity of 2.85 A/W at 4.5 μm when the graphene is tuned to its ENZ condition (corresponding to a chemical potential of 0.46 eV), significantly exceeding the theoretical quantum limit. The device achieves a specific detectivity exceeding 5×1013 Jones at room temperature without requiring cryogenic cooling, and a 3-dB bandwidth of 18 GHz for a device length of 3 μm. The combination of high sensitivity, room-temperature operation, and wavelength tunability makes this photodetector architecture particularly suitable for applications in gas sensing, biomedical diagnostics, and thermal imaging. Compared to conventional MIR photodetectors, our proposed structure demonstrates superior performance metrics while enabling electrical selection of the detection wavelength, establishing a promising platform for next-generation infrared sensing technologies.

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