Nanorod Arrays Enhanced UV Light Response of Mg-Doped ZnO Films

Abstract

Zn1−xMgxO (x = 0, 0.03, 0.05, and 0.07) nanocrystalline films were grown on silicon substrates using the sol–gel method. Furthermore, Zn1−xMgxO vertically aligned hexagonal symmetrical nanorods with six reflection symmetries were fabricated on pure ZnO-seeded layer n-type silicon substrates via a low-temperature hydrothermal method to enhance the ultraviolet (UV) light response. The crystal microstructures and surface morphologies of nanocrystalline films and nanorod arrays were determined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Transmission spectra showed that the increasing Mg content will increase the band gap energy from 3.28 to 3.46 eV. However, the current–voltage curves in the dark and under UV illumination showed that the UV response did not improve by the incorporation of magnesium. We changed the flat surface of films into symmetrical nanorod arrays and demonstrated they can significantly enhance the normalized photo-to-dark-current ratio up to ten times.

Keywords

• ZnO
• sol–gel
• hydrothermal growth
• nanorod arrays
• light response