Electrical resistivity mapping of potassium-doped few-layer CVD graphene by EBAC measurements

Abstract

The electron beam absorbed current (EBAC) method identifies the open and/or short points in various semiconductor devices, which can be applied to characterize the current path and local resistance in graphene. In this study, potassium (K)-doped few-layer graphene with inhomogeneous K atoms seemed to be one of the appropriate materials to characterize the current path by EBAC. Nonuniform contrast in the EBAC image due to inhomogeneous local resistances is observed, which is explained by the variation of the Fermi level in the graphene channel from the G-band peak shifts from Raman spectroscopy. The changes in the contrast of the EBAC images are obtained by applying a gate voltage. These changes are attributed to the modulation of the local carrier densities by applying the gate voltage. For comparison, uniform contrast in EBAC images and uniform G-band peak positions of undoped few-layer graphene field effect transistors are confirmed. The obtained results suggest that homogeneous Fermi level leads to a uniform current path. EBAC enables us to evaluate the uniformity of local resistance and current through a pass in the graphene channel, which can be applied to other two-dimensional materials, such as transition metal dichalcogenides, graphene oxide, and hexagonal boron nitride.

Rigid-Flexible Coupling Modification Strategy Realized by Combining MXene with C-Coated Microsilicon for Long-Life Li-Ion Battery

“…For example, Li et al coated a carbon (C) layer on the surface of Si nanoparticles to resist their volume expansion, but the rigid C shell is easily damaged by the stress accumulated from the volume expansion during lithiation. To ensure conductivity while improving the flexibility of the buffer layer, research has focused on developing some flexible conductive substrates, such as graphene − and carbon nanotubes. − However, the preparation process of graphene and carbon nanotubes often requires harsh conditions or involves complex synthesis processes that add extra cost to the product. − Comparatively, MXene, as a novel transition metal carbide or nitride, combines the properties of graphene and graphene oxide with good electrical conductivity, surface chemistry, hydrophilicity, and excellent mechanical properties, which can be used as a good conductive substrate material. − Moreover, its preparation method by etching in LiF-dissolved HCl solution is simple and mild, and it is suitable for large-scale production and application. The general structural formula of MXene is M n +1 X n T x ( n = 1, 2 or 3), in which M represents the former transition metal element, X represents the carbon or/and nitrogen, and T x represents the surface functional group associated with the M layer, such as −F, −O, −OH, etc. , Among them, Ti 3 C 2 T x is the most representative of the MXenes family and has been applied as a conductive buffer substrate for silicon-based anodes.…”