Abstract
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 k⸱p 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 (λ) 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 (ηRAD). In addition, due to the dominant transverse-electric (TE)-polarized emission from the AlGaN-delta-GaN QW structure, the light extraction efficiency (ηEXT) is greatly enhanced when compared to a conventional AlGaN QW. Combined with the large ηRAD, this leads to the significant enhancement of external quantum efficiency (ηEQE), indicating that AlGaN-delta-GaN structures could be a promising solution for high-efficiency DUV LEDs.
Highlights
Ultraviolet (UV) light sources with emission wavelengths (λ) from 200 to 280 nm (UVC range) have been demonstrated to be the most efficient solution for surface/air/water sterilization [1,2,3,4]
Combined with the large ηRAD, this leads to the significant enhancement of external quantum efficiency, indicating that AlGaN-delta-GaN structures could be a promising solution for high-efficiency DUV light-emitting diodes (LEDs)
We examined the physics and optical properties of AlGaN-delta-GaN active regions with differing delta-GaN thickness, barrier Al content, and quantum well (QW) Al content using a self-consistent six-band k·p model
Summary
Ultraviolet (UV) light sources with emission wavelengths (λ) from 200 to 280 nm (UVC range) have been demonstrated to be the most efficient solution for surface/air/water sterilization [1,2,3,4]. Cost and quantum efficiency issues currently impede DUV LEDs from completely replacing conventional DUV light sources such as mercury arc lamps. Several challenges continue to limit the external quantum efficiency (ηEQE ) of DUV LEDs to less than 10% [1,2,5], namely the lack of a native growth substrate, difficult p-type doping, and a large refractive index mismatch between the III–V semiconductor and air. There is much room for the further improvement of overall device efficiency, especially in the active region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
