Gallium nitride (GaN) is a key component in optoelectronics, such as light-emitting diodes (LED). The investigation and identification of point defects in GaN is very important and has immediate technology relevance to longer life time LEDs. The goal of the proposed research is to bring the physics of defects in GaN to a new level of understanding, to uncover the microscopic nature of defects, and to solve longstanding problems in the field of semiconductor physics. The research integrates experiment and theory by combining advanced experimental techniques with high performance computing. Collaboration with the semiconductor industry is expected to have a direct impact on practical applications. The project also builds a strong foundation for research and education in a relatively small Physics Department at Virginia Commonwealth University. Students from underrepresented groups have the opportunity to gain hands-on experience with state-of-the-art experiment and calculations.
goal of this research is to gain an in-depth and comprehensive understanding of point defects in GaN. The study investigates a large number of point defects and various defect complexes. The experimental work, using advanced tools such as photoluminescence under uniaxial stress, is conducted in parallel with first-principles calculations using the hybrid functional theory. Incorporation of lattice deformations due to uniaxial pressure into the theory enables direct comparison between the theory-predicted changes in defect-related optical properties and experimental results. The symmetry and electronic structure of point defects can be revealed from the analysis of the effect of external stress based on the luminescence spectrum and its polarization. The integrated experiment/theory approach allows the direct identification of defects and the determination of their microscopic structure.
