Electrically Driven Strain‐Activated Defect Emission from Hexagonal Boron Nitride at Room Temperature

Defect‐related emission in hexagonal boron nitride (hBN) could operate at room temperature with high brightness, enabling potential applications in quantum photonics. However, limited by the large bandgap of hBN, defect emission in hBN has mainly been excited in optical ways. Herein, with an Ag nanowire/hBN/graphene tunnel junction, electrically driven strain‐activated defect emission from hBN is demonstrated. The Ag nanowire serves as both the bottom electrode and the strain source to activate the defect in hBN. Under external biases, quantum tunneling occurs preferably at the defect regions in hBN layers, i.e., local conduction channels, leading to sub‐band transition (or defect emission with the electron–photon coupling efficiency about 10 −6 ) from hBN. The bias‐induced electroluminescence spatially overlaps with the laser excited photoluminescence with bias‐independent spectra, indicating that both are originating from the same defects. The research extends the study of defect emission in hBN from optical excitation to electrical excitation, which paves the way for electrically driven hBN‐based light sources.