Effect of annealing temperature on surface morphology and work function of ZnO nanorod arrays

• The 600°C and 450°C isothermal sections of the Zn-Fe-B system are determined.
• The solubility of Zn in Fe2B and FeB at 600°C is 1.8 at.% and 2.5 at.%, respectively.
• The solubility of Zn in Fe2B and FeB at 450°C is 1.7 at.% and 2.1 at.%, respectively.
• All Fe-Zn compounds can be in equilibrium with Fe2B at 450°C.
• Both FeB and Fe2B are in equilibrium with the liquid phase at 600°C.

A simple and effective method of fabricating nanomaterials and the understanding of their electronic structures are significant for designing novel nanodevices. In this study, ZnO nanorod arrays on ITO substrate were synthesized by electrochemical deposition, and the effect of annealing temperature on surface morphology and especially work function was investigated using various techniques. The results indicated that the formation of hexagonal ZnO nanorod arrays with (0 0 0 1) orientation was strongly associated with the annealing temperature. The work function of well-aligned ZnO nanorod arrays is 4.84 eV, which shows an obvious dependence on the arrangement of ZnO nanorod arrays. These changes in work function of ZnO nanorod arrays (e.g., used as the photoanode of dye-sensitized solar cells) are important to understand the electron transport of related nanodevices.