Epitaxial ZnO/Pt layered structures and ZnO-Pt nanodot composites on sapphire (0001)

We report the epitaxial growth and properties of ZnO-Pt layered structures and ZnO-Pt nanodot composites on sapphire (0001) substrates fabricated by using the pulsed laser deposition (PLD) technique. Heteroepitaxial growth of these structures was accomplished by using domain-matching epitaxy. The heterostructures were characterized using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), optical transmittance, photoluminescence, and electrical resistivity measurements. XRD and HRTEM experiments revealed the epitaxial nature of these structures, with orientation relationship between ZnO and Pt, as [0001](ZnO)parallel to[111](Pt) and [(2) over bar 110](ZnO)parallel to[011](Pt), which is equivalent to no rotation between ZnO and Pt. For Pt epitaxy on (0001) sapphire, the epitaxial relationship was determined to be [001](Pt)parallel to[0001](Sap) and [110](Pt)parallel to[01 (1) over bar0](Sap) which is equivalent to a 30 degrees rotation in the basal plane. Electrical and optical measurements showed that these heterostructures exhibit very high electrical conductivity and at the same time possess interesting optical transmittance spectra and exhibit room temperature photoluminescence characteristics.