Effect of temperature on hydrothermally grown high-quality single-crystals Mg-doped ZnO nanorods for light-emitting diode application

Abstract

Single crystal Mg-doped ZnO nanorods (NRs) are successfully deposited onto ZnO-seeded Si substrate through a facile hydrothermal method using Zn and Mg nitrates as precursor and dopant, respectively. Field-emission scanning electron microscopy observations reveal that both surface morphology and topography depend significantly on growth temperature. At deposition temperature of 150°C; unidirectional tapering pyramidal-shaped Mg-doped ZnO NRs with high density was obtained, which is favorable for light-emitting diode (LED) application. X-ray diffraction analysis confirms the formation of pure single phase hexagonal (Wurtzite) structure while photoluminescence study shows a strong UV emission at 378nm. The optimized tapering pyramidal-shaped Mg-doped ZnO NRs have also been grown onto p-GaN and the (ZnO:Mg NWs)/(p-GaN) heterojunction has been used to fabricate an LED device. The electroluminescence (EL) spectra under forward bias show that the diode emits a unique UV-light centered at 382nm. The as-obtained results highlight the effectiveness of deposition temperature on Mg-doped ZnO NRs as an active layer during the fabrication of UV-LED device.