Modification in structural, electrical and defect luminescence properties of ZnO nanorod films with Cu, Al and double-doping

Abstract

Zinc oxide nanorods have broad application prospects in the field of photoelectric devices. However, the application as photodetectors in the visible light band is limited by their narrow luminescent spectrum and poor electrical conductivity. In this work, three different zinc oxide nanorod films respectively with Cu, Al and double-doping have been prepared for investigating the modifying effect of their defect luminescence and electric performance. In this paper, Cu doped zinc oxide with rod structure and Al doped zinc oxide with flaky structure are fabricated by hydrothermal method and sol-gel method, respectively. As for the double-doping, Al doped zinc oxide films are grown on the surface of Si by sol-gel method, and Cu doped zinc oxide nanorods are grown on the surface of Al doped zinc oxide films by hydrothermal method. The results show that the Cu doping can improve the number of defects, leading to the electrons transport from VZn to Zni and then releasing the photons. Alternatively, the trivalent aluminum ions exist in zinc oxide nanorods in the form of replacement or gap, increasing the carrier concentration, turn-on voltage and rectification ratio of zinc oxides. As for the Cu–Al double-doping, Al doped zinc oxide films are located between Cu doped zinc oxide nanorods and Si substrate and work as an intermediate layer of current. Trivalent aluminum ions can change the semiconductor properties of zinc oxide and make it have the performance of p-type semiconductor which can improve the electrical properties of zinc oxide semiconductor. Besides, the carrier concentration of Cu–Al double-doping zinc oxide is nearly 3 times higher than that of pure one. Increasing the carrier concentration can increase the current of ZnO–Si heterojunction in the dark, thus improving the photoelectric properties of ZnO nanorods.