Influence of Quantum-Well Width on the Electroluminescence Properties of AlGaN Deep Ultraviolet Light-Emitting Diodes at Different Temperatures

• Published in: Nanoscale research letters Vol. 13; no. 1; pp. 334 - 5
• Main Authors: Tan, Shuxin, Zhang, Jicai, Egawa, Takashi, Chen, Gang, Luo, Xiangdong, Sun, Ling, Zhu, Youhua
• Format: Journal Article
• Language: English
• Published: New York Springer US 23.10.2018; Springer Nature B.V; SpringerOpen
• Subjects: AlGaN; Chemistry and Materials Science; Deep ultraviolet light-emitting diodes; Electroluminescence; Electrons; External quantum efficiency; Light emitting diodes; Low temperature; Materials Science; Molecular Medicine; Nano Express; Nanochemistry; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Organic light emitting diodes; Overflow; Quantum efficiency; Quantum wells; Radiative recombination; Recombination; Temperature; Temperature effects; Theoretical analysis; Ultraviolet radiation; Electroluminescence; Deep ultraviolet light-emitting diodes; External quantum efficiency; AlGaN; Low temperature
• ISSN: 1931-7573; 1556-276X
• DOI: 10.1186/s11671-018-2756-2

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.