Synthesis and characterization of ZnO columns grown on MgO-coated silicon substrates by carbon-thermal evaporation

Zinc oxide columns have been grown on an MgO-coated silicon (111) substrate by the carbon-thermal evaporation method at 1050 °C. The MgO layer obtained from the substrate pre-dripped in Mg(NO3)2 solution by the use of a dropper can solve the troublesome lattice mismatch problem in the heteroepitaxy and promote the growth of ZnO columns effectively. The as-prepared ZnO structures were characterized by using X-ray diffraction (XRD), field-emission transmission electron microscope (FETEM), selection area electron diffraction (SAED), and photoluminescence (PL) spectrum. The results show that the columns are highly crystalline with the wurtzite hexagonal structure, and grow along the [0001] in the c-axis direction. Photoluminescence (PL) spectra of the as-synthesized microstructures exhibit broad green emission peaks at ∼514 nm. In addition, the growth mechanism of the two ZnO structures is discussed based on the analysis briefly based on the time-dependent experiment.

Research highlights
► The column shaped ZnO microstructures are every rare in the past articles.
► The prepared MgO layer on the substrate can solve the troublesome lattice mismatch problem and promote the growth of ZnO columns effectively.
► The grown ZnO columns with a stronger green light emission at ∼514 nm have good application in white light emitting diodes.
► The carbon-thermal evaporation method is a simple and cost-effective approach for growing columns on a relatively large scale.