ZnO/GaN heterostructure for LED applications

Author： Titkov I. E. Delimova L. A. Zubrilov A. S. Seredova N. V. Liniichuk I. A. Grekhov I. V.

ISSN： 1362-3044

Source： Journal of Modern Optics, Vol.56, Iss.5, 2009-03, pp. : 653-660

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Abstract

White electroluminescence (EL) from ZnO/GaN structures fabricated by pulsed laser deposition of Zn:In onto GaN:Mg/GaN structures MOCVD-grown on Al2O3 substrates has been observed. The white light is produced by superposition of two strongest emission lines, narrow blue and broad yellow, peaked at 440 and 550 nm, respectively. The intensity ratio of different EL lines from ZnO/GaN/Al2O3 structures depends on the ZnO film quality and drive current. The white EL is due to the high density of structural defects at the n-ZnO/p-GaN interface. A band diagram of the n-ZnO/p-GaN/n-GaN is constructed and a qualitative explanation of the EL is given. Conditions of ZnO deposition strongly affects the properties of the recombination emission and predetermines the EL spectrum of the LED structure if it does not have high quantum efficiency (more than 1%) such as in commercial LEDs.