Influence of ZnO/graphene nanolaminate periodicity on their structural and mechanical properties

Abstract

Structural, electronic and mechanical properties of ZnO/Graphene (ZnO/G) nanolaminates fabricated by low temperature atomic layer deposition (ALD) and chemical vapor deposition (CVD) were investigated. We performed scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS) and nanoindentation to characterize the ZnO/G nanolaminates. The main structural and mechanical parameters of ZnO/G nanolaminates were calculated. The obtained results were analyzed and interpreted taking into account mechanical interaction and charge effects occurring at the G-ZnO interface. The influence of graphene sublayers number on the mechanical behavior of the ZnO/G nanolaminates was studied. By reducing the bilayer thickness, the mechanical parameters of the films can be tuned 2 (Young's modulus 100-200 GPa, hardness 3-9 GPa). The softer response of the multilayers as compared to the single layers of ZnO and graphene was attributed to the structural changes in the ZnO layer and the interfaces. This study shows the mechanical behavior of ZnO/G nanolaminates and their influence on the development of novel electro-optical devices based on these structures.

Calcination-Free Synthesis of Porous Metal Oxides/Carbon from Calcium Carbide by Ball Milling

“…For Fe 3 O 4 /C in Figure a, the peaks at 30.1, 37.1, 53.4, 57.0, 62.5, and 73.9° corresponded to the (220), (222), (422), (511), (440), and (533) crystal planes of Fe 3 O 4 (PDF #19-0629) . The carbon support with crystallinity was observed in ZnO/C (Figure a) at the peak of 29.2°, which was attributed to the activation behavior of ZnCl 2 for the polymerization of the carbon radical C 2 2– . , Further, ZnO/C displayed the typical pattern of hexagonal P63mc ZnO (PDF #36-1451), , owning peaks at 31.8, 34.4, 36.3, 47.5, 56.6, 62.9, and 68.0°, which related to the (100), (002), (101), (102), (110), (103), and (201) crystal planes. The diffraction peaks of Cu 2 O/C at 29.6, 36.4, 42.3, 61.3, and 73.5° indicated the (110), (111), (200), (220), and (311) crystal faces of cubic Pn-3m Cu 2 O (PDF #05-0667).…”

Improved Crystalline Structure and Enhanced Photoluminescence of ZnO Nanolayers in Bi2Se3/ZnO Heterostructures

“…14 Improvement of ZnO crystalline structure in the layers with thicknesses below 50 nm was demonstrated in Al 2 O 3 /ZnO and graphene/ZnO nanolaminates, where ZnO layers were deposited on Al 2 O 3 and graphene layers, respectively. [15][16][17][18] In addition to improvement of the crystalline structure, the optical properties of ZnO in the nanolaminate structures were found to be dependent also on charge transfer on the interface between ZnO and Al 2 O 3 , and between ZnO and graphene. [15][16][17][18] Modelling of Al 2 O 3 /ZnO heterostructures confirmed that the combination of ZnO (band gap ~3.3 eV) with a material with larger band gap as Al 2 O 3 (band gap ~ 6eV) results in increase of the photoluminescence (PL) of ZnO in Al 2 O 3 /ZnO heterostructure due to the charge transfer at the interfaces and decrease of the surface potential in ZnO upper layers.…”

“…[15][16][17][18] In addition to improvement of the crystalline structure, the optical properties of ZnO in the nanolaminate structures were found to be dependent also on charge transfer on the interface between ZnO and Al 2 O 3 , and between ZnO and graphene. [15][16][17][18] Modelling of Al 2 O 3 /ZnO heterostructures confirmed that the combination of ZnO (band gap ~3.3 eV) with a material with larger band gap as Al 2 O 3 (band gap ~ 6eV) results in increase of the photoluminescence (PL) of ZnO in Al 2 O 3 /ZnO heterostructure due to the charge transfer at the interfaces and decrease of the surface potential in ZnO upper layers. 16 On the other hand, forming of heterostructures of ZnO and 5 nanomaterials with the lower in comparison with ZnO band gap is advantageous for optoelectronic applications related to photoactive charge separation in visible and NIR range.…”

“…Among different methods of fabrication, atomic layer deposition (ALD) provides homogeneous and conformal coating of ZnO on substrates with different shapes and surface roughnesses. − Structure and optical properties of ZnO depend on type of substrate, temperature of deposition, and thickness of the deposited layers. − It was shown that the transition from an amorphous to a crystalline structure in ZnO layers was observed with an increase of the layer thickness beyond 50 nm . Improvement of the ZnO crystalline structure in the layers with thicknesses below 50 nm was demonstrated in Al 2 O 3 /ZnO and graphene/ZnO nanolaminates, where ZnO layers were deposited on Al 2 O 3 and graphene layers, respectively. − In addition to improvement of the crystalline structure, the optical properties of ZnO in the nanolaminate structures were found to be dependent also on charge transfer at the interface between ZnO and Al 2 O 3 , and between ZnO and graphene. − Modeling of Al 2 O 3 /ZnO heterostructures confirmed that the combination of ZnO (band gap ∼3.3 eV) with a material with a larger band gap such as Al 2 O 3 (band gap ∼6 eV) results in an increase of the photoluminescence (PL) of ZnO in the Al 2 O 3 /ZnO heterostructure due to the charge transfer at the interfaces and a decrease of the surface potential in the ZnO upper layers . On the other hand, forming the heterostructures of ZnO and nanomaterials with the lower band gap in comparison with that of ZnO is advantageous for optoelectronic applications related to photoactive charge separation in the visible and NIR ranges.…”

Porous Silicon-Zinc Oxide Nanocomposites Prepared by Atomic Layer Deposition for Biophotonic Applications

“…One of the most well developed and facile techniques for the deposition of thin metal oxide films on porous materials is atomic layer deposition (ALD) [16,37,38]. This technique allows for the fabrication of highly conformal films of ZnO and other metal oxides over the PSi surface and the production of high-quality nanocomposites in comparison to other methods [4,5,39].…”