The Quenching Mechanism and Suppressing Method of Single-Photon Emitters from Point Defects in GaN.

The defect-based single-photon emitters (SPEs) in gallium nitride (GaN) have attracted considerable research interest due to their high emission rate, narrow line width, and room-temperature operation. However, the quenching effect greatly restricts the applications of these SPEs, and the origin of the quenching mechanism is still unclear. Here, based on systematic ab initio calculations, we reveal a possible quenching mechanism originating from the transformation between two different structures of the defect-pair NV in wurtzite GaN. Our results indicate that the defect-pair NV possesses two stable detect-structures A and B, where the structure B has a small zero phonon line (ZPL) and long lifetime. The transformation barrier from structures A to B is only 0.097 eV. Thus, structure A can easily transform to structure B under laser illumination due to thermal fluctuations, causing a quenching phenomenon. Our work also predicts that the barrier energy between defect structures A and B could be effectively adjusted through tuning the triaxial compressive strain of the crystal structure. This provides an effective method to suppress the quenching effect of defect-pair NV in GaN, paving the way for practical applications of SPEs.