Apparent Barrier Height in Scanning Tunneling Microscopy Revisited

Abstract

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Quantitative atom-resolved force gradient imaging using noncontact atomic force microscopy

“…16 Note that this occurs when the force interaction becomes strong, and so perturbation of the local atom positions might be occurring as well as electronic barrier quenching. 17 The whole approach and retraction process remains reversible provided the separation is not reduced beyond the point at which the measured stiffness becomes positive ͑i.e., the point of inflection on the binding energy curve͒. The curve shown here is a single approach curve and is not averaged over several different measurements.…”

Field-Induced Deformation as a Mechanism for Scanning Tunneling Microscopy Based Nanofabrication

“…Simultaneously, the jump-to-contact voltage is increased by 7% compared to the value predicted from Eq. (8). The jump-to-contact voltage V C is seen to be rather insensitive to the radius of curvature of the tip ͑V C~R 20.25 ͒, quite sensitive to the reduced Young's modulus ͑V C~p Y r ͒, and very sensitive to the equilibrium tunnel gap ͑V C~h 1.25 0 ͒.…”

“…Direct interaction due to the interatomic potentials between atoms on the tip and the sample can cause significant deformations of both tip and sample [1][2][3][4][5][6]. Such direct interaction has important consequences for measurements of the absolute tip position [7], the tunnel barrier height [8], the atomic corrugation of surfaces [1,9], and the phenomenon of jump to contact, where a mechanical instability causes tip and sample to suddenly join [3,4].…”

New directions in point-contact spectroscopy based on scanning tunneling microscopy techniques (Review Article)

“…When tip and sample are still far from each other the two minima of this potential are well separated; this means that the restoring spring force is stronger thus keeping the tip apex atoms bound to the tip structure. While decreasing the tip-sample distance the metallic adhesive force between tip and sample becomes stronger than the restoring spring force; to minimize their energy the atoms of the tip relax towards a new potential minimum and the tip is thus abruptly brought in contact with the sample [38,39,42]. Transport abruptly changes from tunneling to contact regime.…”

“…1 in which an Ir tip is brought in contact with an Ir surface [32]. Mechanical properties of atomic-sized contacts have been investigated theoretically by molecular dynamics computer simulations and first-principle calculations [36][37][38][39][40][41][42]. The sudden jump-to-contact can be explained by taking into account the balance of forces involved inside the constriction [36,40,42].…”