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ACS Appl Mater Interfaces. 2018 Jan 31;10(4):3761-3768. doi: 10.1021/acsami.7b15946. Epub 2018 Jan 22.

Monolithic Inorganic ZnO/GaN Semiconductors Heterojunction White Light-Emitting Diodes.

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School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University , Jeonju 561-756, Korea.
Department of Mechanical Engineering, University of Houston , Houston, Texas 77204-4006, United States.
Materials Science and Engineering Program and Texas Center for Superconductivity at UH (TcSUH), University of Houston , Houston, Texas 77204, United States.
School of Chemical Engineering, Yeungnam University , Gyeongsan 712-749, South Korea.
Korea Advanced Nano Fab Center , Suwon 443-700, Republic of Korea.


Monolithic light-emitting diodes (LEDs) that can generate white color at the one-chip level without the wavelength conversion through packaged phosphors or chip integration for photon recycling are of particular importance to produce compact, cost-competitive, and smart lighting sources. In this study, monolithic white LEDs were developed based on ZnO/GaN semiconductor heterojunctions. The electroluminescence (EL) wavelength of the ZnO/GaN heterojunction could be tuned by a post-thermal annealing process, causing the generation of an interfacial Ga2O3 layer. Ultraviolet, violet-bluish, and greenish-yellow broad bands were observed from n-ZnO/p-GaN without an interfacial layer, whereas a strong greenish-yellow band emission was the only one observed from that with an interfacial layer. By controlled integration of ZnO/GaN heterojunctions with different postannealing conditions, monolithic white LED was demonstrated with color coordinates in the range (0.3534, 0.3710)-(0.4197, 0.4080) and color temperatures of 4778-3349 K in the Commission Internationale de l'Eclairage 1931 chromaticity diagram. Furthermore, the monolithic white LED produced approximately 2.1 times higher optical output power than a conventional ZnO/GaN heterojunction due to the carrier confinement effect at the Ga2O3/n-ZnO interface.


GaN; ZnO; heterojunction; monolithic; white light-emitting diodes


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