Department of Physics and Astronomy College of Science, King Saud University, Riyadh, Saudi Arabia.
Nanotechnology. 2017 Jun 16;28(24):245203. doi: 10.1088/1361-6528/aa6f7b.
The size of ZnO nanorods (NRs) plays an important role in tuning the external quantum efficiency (EQE) and quality of light generated by white light emitting diodes (LEDs). In this work, we report on the enhancement of EQE and the quality of ZnO NR-based hetrojunction white LEDs fabricated on a p-GaN substrate using a low temperature solution method. Cathodoluminescence spectra demonstrate that ultraviolet (UV) emission decreases and visible deep band emission increases with an increase in the length of the ZnO NRs. The UV emission could be internally reabsorbed by the ZnO NR excitation, thus enhancing the emission intensity of the visible deep band. Photocurrent measurements validated the fact that the EQE depends on the size of ZnO NRs, increasing by 87% with an increase in the length of the ZnO NRs. Furthermore, the quality of white light was measured and clearly indicated an increase in the color rendering indices of the LEDs with an increase in the length of the ZnO NRs, confirming that the quality of light generated by LEDs can be tuned by varying the length of the ZnO NRs. These results suggest that the EQE and visible deep band emission from n-ZnONRs/p-GaN heterojunction LEDs can be effectively controlled by adjusting the length of the ZnO NRs, which can be useful for realizing tunable white LEDs.
氧化锌纳米棒（NRs）的尺寸在调节白光发光二极管（LED）的外量子效率（EQE）和光质量方面起着重要作用。在这项工作中，我们报告了使用低温溶液法在 p-GaN 衬底上制造的基于 ZnO NR 的异质结白色 LED 的 EQE 和光质量的增强。阴极发光光谱表明，随着 ZnO NR 长度的增加，紫外（UV）发射减少，可见深带发射增加。UV 发射可以被 ZnO NR 激发内部再吸收，从而增强可见深带的发射强度。光电流测量验证了 EQE 取决于 ZnO NRs 尺寸的事实，随着 ZnO NRs 长度的增加，EQE 增加了 87%。此外，还测量了白光的质量，清楚地表明随着 ZnO NRs 长度的增加，LED 的显色指数增加，证实了通过改变 ZnO NRs 的长度可以调节 LED 产生的光的质量。这些结果表明，通过调整 ZnO NRs 的长度，可以有效控制 n-ZnONRs/p-GaN 异质结 LED 的 EQE 和可见深带发射，这对于实现可调白光 LED 可能是有用的。
