New Concepts for Production of Scalable Single Layer Oxidized Regions by Local Anodic Oxidation of Graphene

Abstract

A deep comprehension of the local anodic oxidation process in 2D materials is achieved thanks to an extensive experimental and theoretical study of this phenomenon in graphene. This requires to arrange a novel instrumental device capable to generate separated regions of monolayer graphene oxide (GO) over graphene, with any desired size, from micrometers to unprecedented mm2, in minutes, a milestone in GO monolayer production. GO regions are manufactured by overlapping lots of individual oxide spots of thousands µm2 area. The high reproducibility and circular size of the spots allows not only an exhaustive experimental characterization inside, but also establishing an original model for oxide expansion which, from classical first principles, overcomes the traditional paradigm of the water bridge, and is applicable to any 2D‐material. This tool predicts the oxidation behavior with voltage and exposure time, as well as the expected electrical current along the process. The hitherto unreported transient current is measured during oxidation, gaining insight on its components, electrochemical and transport. Just combining electrical measurements and optical imaging estimating carrier mobility and degree of oxidation is possible. X‐ray photoelectron spectroscopy reveals a graphene oxidation about 30%, somewhat lower to that obtained by Hummers' method.

Selective Growth of MAPbBr3 Rounded Microcrystals on Micro-Patterned Single-Layer Graphene Oxide/Graphene Platforms with Enhanced Photo-Stability

“…This is the reason why sample 10%1L shows such large crystallites at the centre of the GO spots while the rest of the spot has less material compared to the surrounding Gr areas. Graphene usually becomes destroyed at the point of contact between the tip of the anodic oxidation system and the substrate (the centre of the GO spots) due to the initial high currents (spark), creating an area of few microns where no graphene or highly defective graphene is present [ 30 , 31 ]. This point is an excellent nucleation site for the PKV, leading to the rapid formation of big crystallites at the centre of the GO spots.…”

“…Local Anodic Oxidation (LAO) in contact mode performed on large areas of graphene substrates was carried out with a previously reported method [ 30 , 31 , 32 ] using a home-made instrument (see Figure S1 of the Supporting Information for details). CVD single-layer graphene substrates of 1 cm 2 size transferred onto quartz by Graphenea (San Sebastián, Spain) were used without further treatment.…”

“…These conditions allow the formation of GO circles of 80–90 µm in diameter ( Figure 1 ) with an oxidation degree of approximately 30%, as previously obtained from the I D /I G intensity ratio, FWHM of G and D bands’ relationship and X-ray Photoelectron Spectroscopy (XPS) measurements in ref. [ 31 ]. Figure 1 b shows the Raman spectra measured inside (GO) and outside (Gr) of the GO circle showing the D, G and 2D peaks with the characteristics of single-layer graphene and graphene oxide [ 33 ], respectively.…”

“…In this work, we demonstrate, using a solution-processed method, the growth of MAPbBr 3 perovskite on single-layer GO/Gr 2D patterns. Millimetre-sized arrays of GO disks of 80 µm in diameter were formed on graphene single-layers on quartz (Gr/quartz), using a unique in-house-developed system for the local anodic oxidation (LAO) [ 30 , 31 ] of Gr. The growth habits were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) to extract morphological and structural information that allows us to present a simple model for controlling the nucleation rate in terms of the initial concentration, number of layers, and the Gr/GO substrate characteristics.…”

Sub-10 nm patterning of few-layer MoS2 and MoSe2 nanolectronic devices by oxidation scanning probe lithography

“…Scanning probe lithography (SPL) includes a variety of high-resolution patterning methods based on the use of a force microscope (AFM) [21][22][23][24][25][26]. Despite the serial processing nature of SPL, the development of mix-and-match processes [27][28][29] or large-area patterning tools [30][31][32] underline the potential of SPL with improved throughput.…”