Cubic III-Nitrides for Photonics: Physics, Materials, and Devices
HMNTL Student Colloquium
March 25, 2025
Jaekwon Lee
University of Illinois Urbana-Champaign, PI Can Bayram
Light-emitting diodes (LEDs), especially InGaN-based LED devices, have achieved remarkable success in solid-state lighting (SSL), contributing to 25 % of energy savings already. However, expected population growth and increasing demand for lighting necessitate a more efficient approach, which can only be realized by solving the issue of the green gap (i.e., the inefficiency of the state-of-the-art green LEDs). Cubic nitride LEDs are proposed as a promising solution to the green gap due to well-documented advantages in the literature. However, there are theoretical and experimental issues in the current approach that need to be innovated in order to translate these material advantages into functional devices and address the green gap with the cubic nitride approach. In this talk, steps toward the realization of cubic nitride LEDs will be tackled in both theoretical and experimental ways. First, three crucial design rules specific to cubic nitride LEDs are suggested, enabling highly efficient theoretical stack design. Second, high-quality, phase-pure cubic GaN is demonstrated and characterized as a template for further material growth. Finally, purely cubic active layers are synthesized and characterized, showing high enough internal quantum efficiency with green emission to make a functional device. Overall, the challenges in cubic nitride-based green LEDs are addressed in the context of energy efficiency, and future challenges are discussed.