Influence of interface coupling on the electronic properties of theAu/MoS2junction

Abstract

Thin films of Au ranging from 7-24 nm were grown on MoS 2 at room temperature using thermal evaporation and studied using scanning tunneling microscopy and ballistic electron emission spectroscopy.Topographic images show the surface morphology of Au transitions from terraced triangles to a mix of terraced hexagonal and irregular-shaped structures as film thickness exceeded 16 nm. Raman spectra reveal the presence of tensile strain in the MoS 2 with thicker Au films and is likely the driving force behind this transition. All samples exhibit a Schottky barrier significantly lower than that predicted by the Schottky-Mott model due to Fermi level pinning at the interface. The pinning mechanism is thought to be caused, in part, by the presence of gap states induced by a weakening of the interlayer Mo-S bonding in the presence of the Au film. Although relatively consistent in thinner films, the Schottky barrier increases concurrently with structural changes on the surface. At the same time, transmission through the interface begins to drop at an increased exponential rate with film thickness. These observations are consistent with a widening separation between the Au and MoS 2 that would reduce the number of gap states and cause transmission through the interface to be more characteristic of quantum tunneling. An increased separation such as this could result from changes in equilibrium conditions at the interface with increasing strain.

Out-of-plane electron transport in finite layer MoS2

“…1 Because transmission occurs over large areas, values extracted from standard IV curves are dominated by sites with lower barrier heights. BEEM spectra from Au on bulk MoS 2 yield higher Schottky barriers (0.48-0.62 eV), 31 most likely at locations without the subsurface defects.…”

“…29 Localized pinning has been observed experimentally in the vicinity of subsurface metal-like defects. 30 The relatively low density of these defects accounts for the conflicting reports of barrier heights found in literature, which range from 0.06 to 0.62 eV 9,28,31,32 and, in some cases, are found to be ohmic. 1 Because transmission occurs over large areas, values extracted from standard IV curves are dominated by sites with lower barrier heights.…”

“…The alignment of the numerical results to the data was made using a least squares fit to the four prominent peaks in the data after assuming the CBM of 8 ML MoS 2 to be similar to the bulk value. 31 The alignment to the 2 ML data was determined in a similar fashion. However, the CBM of the 2 ML data was assumed to be shifted toward higher energies to account for a 0.18 eV increase relative to the bulk.…”

Tunable phase stability and contact resistance of monolayer transition metal dichalcogenides contacts with metal

“…11,13 As a result, reducing the contact resistance between MX 2 s and the metal substrate has become one of the critical problems to be solved. [14][15][16][17][18][19] As can be inferred from several previous studies, interfacial orbital overlapping will facilitate electron tunneling through the interface. 11,13,20,21 However, systematic investigation on the influence of interfacial charge transfer on MX 2 /metal design is still absent.…”

Kitaev magnetism and fractionalized excitations in double perovskite Sm2ZnIrO6

“…The hunt is on to find an experimental evidence of a true Kitaev spin liquid especially in 3D systems. Recently, it has been suggested theoretically that strong SO coupled Mott insulators controlled by Jeff = 1/2 physics such as found in Iridium-based double perovskites (DP) A2BIrO6 (A = La, B = Zn, Mg) support symmetry allowed nearest neighbour interactions such as Heisenberg, Kitaev and symmetric off-diagonal exchange [16][17]. It is advocated that these 3D geometrically frustrated DP systems support [22][23].…”