Cardoux C., Casiez L., Kroemer E., Frauenrath M., Chretien J., Pauc N., Calvo V., Hartmann J.-M., Lartigue O., Constancias C., Barritault P., Coudurier N., Rodriguez P., Vandeneynde A., Grosse P., Gravrand O., Chelnokov A., Reboud V., Direct Bandgap Ge0.846Sn0.154 Photodiodes for Gas Sensing in the Mid-Wave Infrared, (2025) IEEE Journal of Selected Topics in Quantum Electronics, 31 (1), art. no. 3801108, DOI: 10.1109/JSTQE.2024.3520704
High-performance GeSn photodiodes with 15.4% Sn were fabricated on 200 mm Si wafers, achieving a cutoff wavelength of 3.5 µm, making them ideal for methane detection near 3.3 µm.
These photodetectors demonstrated a specific detectivity (D) of 3.76 × 10⁷ cm·Hz¹ᐟ²·W⁻¹* at room temperature — 60× better than previous devices with similar Sn content.
Integrated in a gas cell with a 3.3 µm LED, the system achieves a methane detection limit of 1600 ppm with low noise (0.78%·Hz⁻¹ᐟ²), showing strong potential for practical IR sensing applications.
