UV-Blue and Green Electroluminescence from Cu-Doped ZnO Nanorod Emitters Hydrothermally Synthesized on p-GaN

Abstract

Aqueous solution synthesis of ZnO nanorods on p-GaN(0001) is a low-temperature (< 100 C) and cost-efficient growth technique of high quality emitters for LED applications. We present morphological, optical and structural properties of zinc oxide nanorod arrays grown by a hydrothermal seed layer-free and rapid synthesis (15 min) on p-GaN(0001). We found that the epitaxial layer possesses a close packed hexagonal nanorod morphology and lateral facets are oriented in the same direction for the various nanorods. The effect of Cu-doping on the optical and electroluminescence properties of Cu–ZnO nanorod arrays on GaN substrate is discussed in details. The UV/Blue and green (near-white) emissions were found in both photoluminescence and electroluminescence spectra indicating the possibility to use the synthesized Cu–ZnO/p-GaN hetero-structures in white LED applications. The emissions started at relatively low forward voltage of 4.9 V and the intensity of the emission increased with increasing the biasing voltage. We propose for further exploration an efficient, seed layer-free and low temperature hydrothermal synthesis technique to fabricate Cu-doped ZnO/p-GaN heterojunction light-emitting devices-LEDs.