Single photon emitters (SPEs) are fundamental building blocks for quantum technologies. Ideal SPEs exhibit characteristics such as brightness, stability across diverse environments, linear polarization, and the ability to emit indistinguishable single-photon wave packets. GaN, a technically mature wide bandgap semiconductor extensively employed in various photonic and electronic devices, holds particular promise for on-chip photonic integration. This dissertation explores a series of experiments and theoretical investigations into the distinctive properties of GaN defect-based SPEs. Initially reported in 2017, GaN defect SPEs have a relatively short history. In the first part of this dissertation, we review this brief history along with the established properties of GaN SPEs. Subsequently, we formulate pertinent questions, the answers to which guide us into the main chapters of this study. The dissertation primarily discusses the dephasing mechanism of these SPEs at different temperatures, delves into the optical dipole structure and orientation, and investigates the ultrafast spectral diffusion properties of these emitters. Along this journey, sample nano-fabrication, various optical metrology techniques, optical simulations, and theoretical condensed matter physics come together to form a comprehensive understanding. In the final chapter, we summarize our research on GaN defect quantum emitters and discuss the future outlook for these SPEs in both fundamental research and device applications.