Structurally Nanocrystalline-Electrically Single Crystalline ZnO-Reduced Graphene Oxide Composites

Abstract

ZnO, a wide bandgap semiconductor, has attracted much attention due to its multifunctionality, such as transparent conducting oxide, light-emitting diode, photocatalyst, and so on. To improve its performances in the versatile applications, numerous hybrid strategies of ZnO with graphene have been attempted, and various synergistic effects have been achieved in the ZnO-graphene hybrid nanostructures. Here we report extraordinary charge transport behavior in Al-doped ZnO (AZO)-reduced graphene oxide (RGO) nanocomposites. Although the most challenging issue in semiconductor nanocomposites is their low mobilities, the AZO-RGO nanocomposites exhibit single crystal-like Hall mobility despite the large quantity of nanograin boundaries, which hinder the electron transport by the scattering with trapped charges. Because of the significantly weakened grain boundary barrier and the proper band alignment between the AZO and RGO, freely conducting electrons across the nanograin boundaries can be realized in the nanocomposites. This discovery of the structurally nanocrystalline-electrically single crystalline composite demonstrates a new route for enhancing the electrical properties in nanocomposites based on the hybrid strategy.

Enhanced Charge Transport in ZnO Nanocomposite Through Interface Control Using Multiwall Carbon Nanotubes

“…The mobility of the AZO‐MWCNT nanocomposite [46.5 cm 2 ·(V·s) −1 ] was comparable to the calculated single crystalline mobility based on the BHD model. Interestingly, the mobility in the AZO‐RGO nanocomposite also exhibited single crystalline behavior in our previous study . In contrast, the mobility of the AZO nanocomposite was 13 cm 2 ·(V·s) −1 , which is much lower than the mobility of single crystalline ZnO, thus indicating that the mobility in the AZO nanocomposite was limited by the presence of the grain boundary …”

“…Figures , and show a comparison of the temperature‐dependent charge transport properties of the AZO‐MWCNT nanocomposite with those of the AZO and AZO‐RGO nanocomposites from our previous studies . As seen in Fig.…”

“…(a) Temperature‐dependent carrier concentration in the AZO ‐ MWCNT nanocomposite with that of the AZO and AZO ‐ RGO nanocomposites . (b) Mobilities in the nanocomposites as a function of carrier concentration at room temperature.…”

“…Grain‐boundary scattering could be sufficiently suppressed as a result of the Schottky barrier reduction due to the existence of MWCNTs at the grain boundary. This leads to single crystal‐like charge transport behavior in the AZO‐MWCNT nanocomposite below 873 K. We had previously revealed that the Schottky barrier could be also alleviated by interface control using graphene at the grain boundaries in AZO‐reduced graphene oxide (RGO) nanocomposites at temperatures of up to 1023 K . However, the AZO‐MWCNT nanocomposite exhibited a rather different temperature dependence in terms of its mobility, and the origin is discussed in terms of different charge distributions at the grain boundary based on the type of carbon nanomaterials (CNMs) used.…”

The Composites of Graphene Oxide with Metal or Semimetal Nanoparticles and Their Effect on Pathogenic Microorganisms

“…Many recent studies have focused on microstructure investigation of GO and related materials using SEM analysis due to the facile evaluation possibility of the structure and quality of source or synthesized materials, as well as the assessment of material modifications [20,21,22,23,24]. SEM Elemental Mapping and SEM line scan analysis provide important information about metal- and metalloid-based nanoparticles distribution on the surface of GO-based carrier [25,26,27,28]. The nature of prepared composites was verified by Dynamic Light-Scattering (DLS), i.e.…”