Abstract
The influence of quantum-well (QW) width on electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes (DUV LEDs) was studied at different temperatures. The maximum external quantum efficiency (EQE) ratios of LED with 3.5 nm QW to that with 2 nm increased from 6.8 at room temperature (RT) to 8.2 at 5 K. However, the ratios for LED with 3.5 nm QW to that with 5 nm QW decreased from 4.8 at RT to 1.6 at 5 K. The different changes of EQE ratios were attributed to the decrease of non-radiative recombination and the increase of volume of the active region. From theoretical analysis, the LED with 2-nm wells had a shallowest barrier for electron overflow due to the quantum-confined effect, whereas the LED with 5-nm wells showed the least overlap of electron and hole due to the large internal field. Therefore, the LED with 3.5 nm QW had the highest maximum EQE at the same temperature. As temperature decreased, the current for maximum EQE decreased for all the LEDs, which was believed to be due to the increase of electron which overflowed out of QWs and the decrease of hole concentration. The results were helpful for understanding the combination of polarization effect and electron overflow in DUV LEDs.
Highlights
AlGaN-based deep ultraviolet light-emitting diodes (DUV Deep ultraviolet light-emitting diodes (LEDs)) can be widely used in the fields of solid-state lighting, medicine, biochemistry, and so on
We found the LEDs with QW width of 3.5 nm exhibited the highest maximum external quantum efficiency (EQE)
We studied the influence of QW width on EL properties of AlGaN DUV LEDs at different temperatures
Summary
AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) can be widely used in the fields of solid-state lighting, medicine, biochemistry, and so on. More and more efforts have been devoted to improve the crystal quality of the materials [1–4], the p-type doping techniques, and the optimization of the device structures [5–9]. Miyake et al demonstrated that the AlN crystal quality can be improved significantly by high-temperature annealing [3]. By increasing the growth temperature, Sun et al obtained high-quality AlN thick films on sapphire [2]. We fabricated DUV LEDs with different quantum-well (QW) width and studied the influence of the QW width and temperature on the electroluminescence (EL) properties. We found the LEDs with QW width of 3.5 nm exhibited the highest maximum external quantum efficiency (EQE). The current for the maximum EQE decreased for all the LEDs, which was believed to be due to the decrease of hole concentration and the increase of overflowed electron current
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
