AlGaN-Delta-GaN Quantum Well for DUV LEDs

AlGaN-delta-GaN quantum well (QW) structures have been demonstrated to be good candidates for the realization of high-efficiency deep-ultraviolet (DUV) light-emitting diodes (LEDs). However, such heterostructures are still not fully understood. This study focuses on investigation of the optical properties and efficiency of the AlGaN-delta-GaN QW structures using self-consistent six-band kp modelling and finite difference time domain (FDTD) simulations. Structures with different Al contents in the AlxGa1-xN sub-QW and AlyGa1-yN barrier regions are examined in detail. Results show that the emission wavelength (lambda) can be engineered through manipulation of delta-GaN layer thickness, sub-QW Al content (x), and barrier Al content (y), while maintaining a large spontaneous emission rate corresponding to around 90% radiative recombination efficiency (eta RAD). In addition, due to the dominant transverse-electric (TE)-polarized emission from the AlGaN-delta-GaN QW structure, the light extraction efficiency (eta EXT) is greatly enhanced when compared to a conventional AlGaN QW. Combined with the large eta RAD, this leads to the significant enhancement of external quantum efficiency (eta EQE), indicating that AlGaN-delta-GaN structures could be a promising solution for high-efficiency DUV LEDs.