Kyungjoon Baek

Fabrication and optical properties of ZnO‐sheathed Ga2O3 nanowires

The Ga2O3/ZnO coaxial nanowires were prepared by a two step process: the thermal evaporation of GaN powders and the sputter‐deposition of ZnO. The cores are single crystal monoclinic Ga2O3 and the fcc ZnO shells. The PL emission of Ga2O3 nanowires is slightly decreased by ZnO coating but slightly increased by subsequent thermal annealing in an oxidative atmosphere. The major emission peak is also red‐shifted to ∼550 nm. The O concentration in the Ga2O3 core regions increases significantly during O2 annealing, leading to the increase in the O interstitial and Ga vacancy concentration, resulting in the enhancement in the green emission. In contrast, the PL emission of the wires is significantly increased and the emission peak is red‐shifted from 540 nm to ∼590 nm by annealing in a reducing atmosphere, which presumably originates from the increase in the O vacancy and Ga interstitial concentrations in the Ga2O3 core as a result of the reaction between Ga2O3 and H2. The results obtained in this work will give...

SYNTHESIS AND PHOTOLUMINESCENCE PROPERTIES OF ZnSe-CORE/SnO2-SHELL NANORODS

ZnSe-core/SnO2-shell nanorods have been prepared by using a two-step process comprising the thermal evaporation of ZnSe powders and the atomic layer deposition of SnO2. ZnSe nanorods have been grown by the thermal evaporation of ZnSe powders on gold-coated Al2O3 (0001) substrates. The ZnSe-core/SnO2-shell nanorods were 0.1–0.2 μm in diameter and up to a few tens of micrometers in length. Transmission electron microscopy and X-ray diffraction analysis results indicate that the cores and shells are single crystal zinc blende-type ZnSe and polycrystalline simple orthorhombic-type SnO2, respectively. Photoluminescence measurements show that the ZnSe-core/SnO2-shell nanorods have a strong orange emission band centered at around 650 nm. The orange emission of the ZnSe nanorods is enhanced in intensity by coating them with SnO2 and further enhanced by annealing them. A reducing atmosphere is more efficient in enhancing the orange emission than an oxidative atmosphere. The highest emission intensity is obtained for the shell layer thickness corresponding to 1500 ALD cycles. The orange emission enhancement by annealing is mainly attributed to the formation of Sn interstitials in the ZnSe cores during the annealing process.