Gate-tuned conductance of graphene-ribbon junctions with nanoscale width variations

Abstract

On applying partial gate voltages, we were able to perceive precise and minute conductance variations for the entire graphene electrode, arising mainly from different sub-micrometer scale widths of the graphene ribbons (GRs), which could not be distinguished using conventional global gating methods.

Scanning Gate Microscopic Investigation of Graphene Nanoribbon Underneath Dielectric Layer

“…Since the electric field density between the SGM tip and area A (i.e., narrowest width region) is higher than that for areas B and C, the Fermi level tuning range in area A by V tip is larger than that in areas B and C. Furthermore, the variation in I DS induced by V tip values of −3 to 3 V for position B is smaller than that for positions A and C, indicating that the width of B is the widest in the GNR. The larger Fermi level tuning under the same V tip in positions A and C than in position B of the GNR underneath the HSQ structure can be attributed to a narrower width region on the GNR, leading to a high electric field density between the tip and the sample, as reported previously [20].…”

“…In particular, the current level of the GNR varied with the application of a partial gate via the SGM tip. Based on previous results [20][21][22], we propose that partial width fluctuations in the GNR vary the current in the GNR under the HSQ due to V tip gating. This finding can be applied to analyze the electrical properties of nanoelectronic structures.…”

“…The charge distribution in the channel was characterized based on the conductance image data. In particular, nanoscale channels have been reported to exhibit SGM signal variation owing to charge disorders or dimensional fluctuations of the channel, which change the electric field density with the SGM tip, resulting in current flow variation in the channel [20].…”

“…Herein, we focus on the width fluctuation in the GNR; additional experimental measurements are necessary to confirm the origin of the areas with substantial current variations, which will be investigated more comprehensively in the future. Owing to the indistinguishable topography of the HSQ, we can consider that the permeation of O 2 plasma under HSQ randomly etches the carbon bonds at the edge of graphene, leading to a width fluctuation in the GNR under the HSQ mask [19,20]. This partially induced current difference in the GNR can be manifested by employing the electric field density difference for different widths at positions A, B, and C of the GNR [Fig.…”

Systematic Design and Demonstration of Multi‐Bit Generation in Layered Materials Heterostructures Floating‐Gate Memory

“…The surface potential was obtained by measuring the AC voltage ( V AC ) with a lock‐in amplifier and applying a feedback DC voltage ( V DC ) to cancel the electrostatic force between the Au‐coated tip and sample. [ 44,45 ] Here, while measuring the SKPM data, also V BG = 0 V or ±40 V was applied to observe surface potential with V BG applied.…”