Light Improvement of Near Ultraviolet Light-Emitting Diodes by Utilizing Lattice-Matched InAlGaN as Barrier Layers in Active Region

• Published in: Japanese Journal of Applied Physics Vol. 52; no. 8; pp. 08JL17 - 08JL17-3
• Main Authors: Lu, Yu-Hsuan, Fu, Yi-Keng, Huang, Shyh-Jer, Su, Yan-Kuin, Xuan, Rong, Pilkuhn, Manfred H, Chen, Ying-Chih
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.08.2013
• Subjects: Barriers; Carriers; Confinement; Gallium nitrides; Light-emitting diodes; Mathematical analysis; Optimization; Simulation; Ultraviolet
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.52.08JL17

The effects of lattice-matched InAlGaN used as barriers in the active region were investigated in near ultraviolet light-emitting diodes (LEDs). By changing the thickness of InAlGaN barriers, it is observed that there exists an optimal thickness. Besides the better carrier confinement in the case of using thick barriers, the simulation results showed that hole distribution in the case of using wide barriers should also play a role in the improvement of optical performance. Hence, an excessive increment in the width of barriers will degrade the optical performance contrarily, owing to the accumulated stress and the difficulty in hole transport in the active region from thick barriers. In addition, the calculated energy bandgap of InAlGaN is higher than that of GaN, which is beneficial for increasing the capability of carrier confinement and simultaneously enhancing the radiative recombination. Under 100 mA, the light output power of the LED with 7.3-nm-thick In 0.018 Al 0.09 Ga 0.892 N barriers can be increased by 36% as compared with the LED with GaN barrier.