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Open Access Nano Express

Ultraviolet/blue light-emitting diodes based on single horizontal ZnO microrod/GaN heterojunction

Chia-Fong Du1, Chen-Hui Lee1, Chao-Tsung Cheng1, Kai-Hsiang Lin1, Jin-Kong Sheu12 and Hsu-Cheng Hsu12*

Author Affiliations

1 Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan

2 Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan

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Nanoscale Research Letters 2014, 9:446  doi:10.1186/1556-276X-9-446

Published: 28 August 2014

Abstract

We report electroluminescence (EL) from single horizontal ZnO microrod (MR) and p-GaN heterojunction light-emitting diodes under forward and reverse bias. EL spectra were composed of two blue emissions centered at 431 and 490 nm under forward biases, but were dominated by a ultraviolet (UV) emission located at 380 nm from n-ZnO MR under high reverse biases. Light-output-current characteristic of the UV emission reveals that the rate of radiative recombination is faster than that of the nonradiative recombination. Highly efficient ZnO excitonic recombination at reverse bias is caused by electrons tunneling from deep-level states near the n-ZnO/p-GaN interface to the conduction band in n-ZnO.

Keywords:
ZnO; Microrod; Electroluminescence