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Electroluminescence of ordered ZnO nanorod array/p-GaN light-emitting diodes with graphene current spreading layer.

Dong JJ, Hao HY, Xing J, Fan ZJ, Zhang ZL - Nanoscale Res Lett (2014)

Bottom Line: Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer).In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further.This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on. 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science, China University of Geosciences (Beijing), 29 Xue Yuan Road, Haidian District, Beijing, 100083, China.

ABSTRACT

Unlabelled: Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer). In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further. This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on.

Pacs: 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn.

No MeSH data available.


PL spectra of the ZnO nanorod arrays and EL spectra of the corresponding LEDs. (a) PL spectra of the ZnO nanorod arrays on the p-GaN substrate with different diameters. (b) EL spectra of the LEDs based on ZnO nanorod arrays with different diameters at the injection current of 6 mA.
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Figure 4: PL spectra of the ZnO nanorod arrays and EL spectra of the corresponding LEDs. (a) PL spectra of the ZnO nanorod arrays on the p-GaN substrate with different diameters. (b) EL spectra of the LEDs based on ZnO nanorod arrays with different diameters at the injection current of 6 mA.

Mentions: As mentioned earlier, one of the advantages of the ordered ZnO nanorod array over the ZnO film is the enhanced light emission by virtue of the waveguiding effect of nanorods. Besides, by choosing an optimal diameter of the ZnO nanorod arrays, EL emission can be enhanced further, because the waveguiding property of ZnO nanorods is closely related to the diameter [5,18]. So, the optical properties of the ZnO nanorod arrays with different diameters have been studied, and the corresponding PL and EL spectra are presented in Figure 4. As can be seen in Figure 4a, the PL spectra of the ZnO nanorod arrays on GaN substrates with the diameters of 170, 220, 300, and 380 nm present a unique UV emission at 380 nm, which is due to the NBE emission of ZnO. The absence of any other peaks from ZnO, for example, the defect-related visible emission within the experimental resolution, indicates the high crystal quality of the ZnO nanorod arrays on p-GaN substrates. Figure 4b presents the EL spectra of the ZnO nanorod array-based LEDs with different diameters (170, 220, 300, and 380 nm) at the injection current of 6 mA, and all the four diodes show a dominant NBE emission at 390 nm. Compared with the PL spectra, there is a 10-nm red shift of the EL NBE emission, which is caused by the junction-heating effect under a constant injection current [14,19] and difference between PL and EL processes (the PL process depends on the recombination of nonequilibrium carriers in the surface layer, whereas the EL process is determined via the carrier recombination within the space charge region of heterojunction [20]).


Electroluminescence of ordered ZnO nanorod array/p-GaN light-emitting diodes with graphene current spreading layer.

Dong JJ, Hao HY, Xing J, Fan ZJ, Zhang ZL - Nanoscale Res Lett (2014)

PL spectra of the ZnO nanorod arrays and EL spectra of the corresponding LEDs. (a) PL spectra of the ZnO nanorod arrays on the p-GaN substrate with different diameters. (b) EL spectra of the LEDs based on ZnO nanorod arrays with different diameters at the injection current of 6 mA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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Figure 4: PL spectra of the ZnO nanorod arrays and EL spectra of the corresponding LEDs. (a) PL spectra of the ZnO nanorod arrays on the p-GaN substrate with different diameters. (b) EL spectra of the LEDs based on ZnO nanorod arrays with different diameters at the injection current of 6 mA.
Mentions: As mentioned earlier, one of the advantages of the ordered ZnO nanorod array over the ZnO film is the enhanced light emission by virtue of the waveguiding effect of nanorods. Besides, by choosing an optimal diameter of the ZnO nanorod arrays, EL emission can be enhanced further, because the waveguiding property of ZnO nanorods is closely related to the diameter [5,18]. So, the optical properties of the ZnO nanorod arrays with different diameters have been studied, and the corresponding PL and EL spectra are presented in Figure 4. As can be seen in Figure 4a, the PL spectra of the ZnO nanorod arrays on GaN substrates with the diameters of 170, 220, 300, and 380 nm present a unique UV emission at 380 nm, which is due to the NBE emission of ZnO. The absence of any other peaks from ZnO, for example, the defect-related visible emission within the experimental resolution, indicates the high crystal quality of the ZnO nanorod arrays on p-GaN substrates. Figure 4b presents the EL spectra of the ZnO nanorod array-based LEDs with different diameters (170, 220, 300, and 380 nm) at the injection current of 6 mA, and all the four diodes show a dominant NBE emission at 390 nm. Compared with the PL spectra, there is a 10-nm red shift of the EL NBE emission, which is caused by the junction-heating effect under a constant injection current [14,19] and difference between PL and EL processes (the PL process depends on the recombination of nonequilibrium carriers in the surface layer, whereas the EL process is determined via the carrier recombination within the space charge region of heterojunction [20]).

Bottom Line: Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer).In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further.This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on. 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science, China University of Geosciences (Beijing), 29 Xue Yuan Road, Haidian District, Beijing, 100083, China.

ABSTRACT

Unlabelled: Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer). In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further. This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on.

Pacs: 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn.

No MeSH data available.