Preparation of one dimensional Bi2O3-core/ZnO-shell structures by thermal evaporation and atomic layer deposition

One dimensional(1D) Bi2O3-core/ZnO-shell structures with uniform layer thicknesses were prepared by using a two step process consisting of thermal evaporation of Bi2O3 and ALD of ZnO. Highly straight 1D Bi2O3 structures were synthesized by thermal evaporation of Bi powders on c-plane Al2O3 substrates and then ZnO layers were coated on them by ALD.SEM analysis shows that the oxygen partial pressure must be precisely controlled to obtain straight Bi2O3 nanowires. According to the TEM analysis results the Bi2O3-core is a pure tetragonal ββ- Bi2O3 phase single crystal, while the ZnO-shell is amorphous. Photoluminescence (PL) measurement of the ID core/shell nanostructures under excitation at 325 nm indicates that the critical number of ALD cycle for which a transition from a violet emission characteristic of Bi2O3 to UV and green–yellow emissions characteristic of ZnO occurs is less than 10, suggesting that the wavelength of the emission changes abruptly with an increase in the number of ALD cycle.