Abstract
Defects in the hexagonal boron nitride (h-BN) layer can facilitate the tunneling current through thick h-BN tunneling barriers. We have investigated such current-mediating defects as local probes for materials in two dimensional heterostructure stacks. Besides IV characteristics and negative differential conductance, we have characterized the electrical properties of h-BN defects in vertical graphene-h-BN-Cr/Au tunnel junctions in terms of low frequency current noise. Our results indicate a charge sensitivity of 1.5×10−5 e/Hz at 10 Hz, which is equal to good metallic single electron transistors. The noise spectra at low frequency are governed by a few two-level fluctuators. For variations in the electrochemical potential, we achieve a sensitivity of 0.8 μeV/Hz.
Highlights
Van der Waals (VdW) heterostructures based on graphene and hexagonal boron nitride (h-BN) have attracted immense attention[1,2,3] in recent years both in fundamental physics[4,5,6,7] as well as for technological applications.[8,9]
Various spectroscopic studies have been employed to unravel electronic and phononic properties of h-BN, which are influenced by intrinsic nanometer-scale defect states in exfoliated h-BN crystals.[13,14,15]
The defect states have been observed to enhance the tunneling current across h-BN barriers in VdW
Summary
Van der Waals (VdW) heterostructures based on graphene and hexagonal boron nitride (h-BN) have attracted immense attention[1,2,3] in recent years both in fundamental physics[4,5,6,7] as well as for technological applications.[8,9] Hexagonal BN, structurally isomorphic to graphene with a ∼2% lattice mismatch and with a large bandgap of ∼5.9 eV, has intriguing potential for use as a dielectric layer in functional heterostructures,[10,11] in particular, as atomically smooth tunnel barriers.[8,12] Various spectroscopic studies have been employed to unravel electronic and phononic properties of h-BN, which are influenced by intrinsic nanometer-scale defect states in exfoliated h-BN crystals.[13,14,15]. Defects in h-BN tunnel barrier for local electrostatic probing of two dimensional materials
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