Closed-Space Flux Sublimation Growth and Properties of (Cu-Mn)-Doped ZnO Films in Nanoneedle-Like Morphologies

Abstract

The Cu and Mn co-doped ZnO dilute magnetic semiconductor Zn x O films with unique nanoneedle like structure were deposited at ≤300 • C by a two step closed space flux sublimation and periodic oxidation method. Morphology studies establish complex growth process involving a eutectic metal condensate on the substrate and spontaneous emergence of nanoneedle structure by oxidative process controlled by the vapor-liquid-solid mechanism. X-ray diffraction studies show that Zn 1-x (Cu-Mn) x O films retain the typical wurtzite hcp structure of the un-doped ZnO. The absence of extraneous reflections indicates that neither the Mn and Cu dopant metal clusters nor their oxide phases are included in the nanostructure Zn 1-x (Cu-Mn) x O films. The Raman peaks of Zn 1-x (Cu-Mn) x O nanocrystalline films are consistent with the Raman active phonon modes for ZnO. The red shifted E 2 (Low) and E 2 (high) peaks confirm that Mn and Cu substitute at Zn site in the nanostructure Zn 1-x (Cu-Mn) x O films. Optical transition at direct band gap energy occurs at 3.11 eV and an upward energy shift in the direct band to 3.58 eV is assigned to the quantum size effects of the nanoneedle structure of Zn 1-x (Cu-Mn) x O films.

Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

“…The vertical polypyrrole nanotube and sheath structure are likely to decrease the charge transfer reaction time and thus enhance the charge storage capabilities [38]. Zinc oxide used prominently in various devices such as biosensors [39], light emitting diodes [40], organic solar cells [41], and spintronics [42,43] is a biocompatible, highly stable, and less expensive material as compared to ruthenium oxide and therefore has a good potential for the electrochemical energy storage devices. Zinc oxide characterized as a wide band gap semiconductor with excellent chemical and physical properties can be easily transformed in various nanostructure forms like nanowire, nanoplatelets, and nanoneedles mostly as flat two-dimensional structures [44].…”