Enhanced performance of AlGaN-based ultraviolet light-emitting diodes with linearly graded AlGaN inserting layer in electron blocking layer |
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Authors: | Guang Li Lin-Yuan Wang Wei-Dong Song Jian Jiang Xing-Jun Luo Jia-Qi Guo Long-Fei He Kang Zhang Qi-Bao Wu Shu-Ti Li |
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Institution: | Guangdong Engineering Research Center of Optoelectronic Functional Materials and Devices;Guangdong Institute of Semiconductor Industrial Technology;School of Intelligent Manufacture and Equipment |
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Abstract: | The conventional stationary Al content Al GaN electron blocking layer(EBL) in ultraviolet light-emitting diode(UV LED) is optimized by employing a linearly graded Al Ga N inserting layer which is 2.0 nm Al_(0.3) Ga_(0.7) N/5.0 nm Alx Ga_(1-x) N/8.0 nm Al_(0.3) Ga_(0.7) N with decreasing value of x. The results indicate that the internal quantum efficiency is significantly improved and the efficiency droop is mitigated by using the proposed structure. These improvements are attributed to the increase of the effective barrier height for electrons and the reduction of the effective barrier height for holes,which result in an increased hole injection efficiency and a decreased electron leakage into the p-type region. In addition,the linearly graded AlGaN inserting layer can generate more holes in EBL due to the polarization-induced hole doping and a tunneling effect probably occurs to enhance the hole transportation to the active regions, which will be beneficial to the radiative recombination. |
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Keywords: | ultraviolet light-emitting diode electron blocking layer internal quantum efficiency |
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