Broadband shortwave infrared GeSn light-emitting diode at room temperature fabricated by exploring the Sn content gradient method

Broadband shortwave-infrared (SWIR) light-emitting diodes (LEDs) are highly sought after for various sensing applications. In this study, we propose a novel, to the best of our knowledge, GeSn bandgap gradient structure to achieve broadband LEDs. We successfully fabricated GeSn LEDs that operate at room temperature and exhibit a broad emission spectrum by employing the Sn composition gradient technique. In the active layer, the Sn content gradually increased from 9% to 10.8%, resulting in electroluminescence (EL) ranging from 1700 to 2400 nm. Detailed spectral analysis revealed that the EL transition originates from the direct bandgap of GeSn. These findings suggest that the Sn composition gradient approach in GeSn structures holds significant promise for the development of wide-spectrum SWIR LEDs suitable for a range of sensing applications.