Observation of Interlayer Excitons in Mixed-Dimensional MoS₂and InGaN/GaN Quantum Well Heterojunctions

Mixed-dimensional heterojunctions (HJs) between compound semiconductors and transition metal dichalcogenides (TMDCs) provide a versatile platform for modulating interfacial exciton dynamics. While compound semiconductors offer precise compositional control for bandgap tuning across wide spectral ranges, they exhibit weak exciton binding energies that limit exciton stability at room temperature. Mixed-dimensional HJs address this limitation by integrating compound semiconductors with TMDCs, whose strong quantum confinement and reduced dielectric screening enable the formation of stable interlayer excitons with enhanced light-matter coupling. Here, we demonstrate a mixed-dimensional heterojunction comprising trilayer MoS₂ interfaced with an Al₂O₃/InGaN/GaN single quantum well (QW), designed to investigate interlayer exciton behavior. Quantum confinement in the QW localizes carriers near the heterointerface, allowing direct observation of interlayer excitonic states. Low-temperature photoluminescence measurements revealed a distinct emission peak at 2.02 eV, indicating the formation of interlayer excitons at the heterointerface. This strategy offers a unique approach for engineering exciton dynamics in mixed-dimensional systems, with implications for optoelectronic devices that leverage tailored interfacial exciton dynamics.