Strain‐Engineered Monolithic Multi‐Band LEDs for Simultaneous Short‐Wavelength and Mid‐Wavelength Infrared Emission

Multiple quantum well (MQW) light-emitting diodes (LEDs) provide precise wavelength control, making them ideal light sources. However, achieving simultaneous short-wavelength infrared (SWIR, 1-3 µm) and mid-wavelength infrared (MWIR, 3-5 µm) emission from a single LED presents significant technical challenges due to lattice mismatch and reduced quantum efficiency when MQW structures with distinct bandgap energies are integrated onto a single substrate. As a result, most LEDs typically operate in only one IR band. In this study, monolithic multi-band MQW LEDs capable of simultaneous SWIR and MWIR emission are demonstrated. Strain engineering via Sb doping in the QWs induces well-distributed local lattice distortions, such as modulations of atomic bond angles and lengths, leading to balanced strain compensation and coherent epitaxy with atomically sharp interfaces within the MQWs. Reducing the QW thickness of InAsSb enhances quantum confinement, enabling simultaneous SWIR and MWIR emission at 2.87 and 3.18 µm. To further extend the emission range, a simulation-based fabrication feasibility map is developed, and an additional monolithic LED that emits simultaneously at 2.63 and 3.34 µm is fabricated. The monolithic integration of multi-band emission into a single device not only reduces size and complexity but also facilitates multispectral analysis for future optoelectronic devices.