Room Temperature van der Waals Epitaxy of Metal Thin Films on Molybdenum Disulfide

Abstract

Transmission electron microscopy, in particular selected area electron diffraction, was used to investigate the orientational relationship of Al, Ag, Cu, Mn, Mo, Ni, Pd, Ru, Re, and Zn deposited via physical vapor deposition on MoS 2 at room temperature. Past work has shown that a few facecentered cubic (FCC) metals (Ag, Au, Pb, Pd, and Pt) could be deposited epitaxially on MoS 2 . However, we found that additional FCC metals (Al and Cu) could be deposited epitaxially at room temperature on MoS 2 with the orientational relationship M(111)∥MoS 2 (0001) and M[22̅ 0]∥MoS 2 [112̅ 0], while a hexagonally close-packed (HCP) metal Zn was epitaxial on MoS 2 with a M(0001)∥MoS 2 (0001) and M[112̅ 0]∥MoS 2 [112̅ 0] relationship. However, the FCC metal Ni, body-centered cubic metal Mo, and HCP metals Re and Ru were not epitaxial on deposition or even after annealing at 673 K for 4 h. By comparing the results with both physical constants and modeling of the metal/MoS 2 systems, we observed that metals with a close-packed plane with six-fold symmetry, a high homologous temperature, and a low barrier to surface diffusion on MoS 2 are more likely to grow epitaxially at room temperature on MoS 2 .

Low-frequency Raman signature of Ag-intercalated few-layer MoS2

“…At 2 at%, the LF-modes' frequencies reverse their trends and blue-shift compared to their values at a lower silver concentration. The origins of this trend-reversal will be discussed in more detail below, but it should be noted that experimental samples are expected to have Ag-concentrations well below 1 at% [13]. In the red-shift region, linear functions can be fit to the ω(C Ag ) curves (dashed lines in figure 1 the LBM is more sensitive to C Ag than its SM counterpart in a given system with the absolute fitted slopes for LBM being about a factor of two larger than the corresponding ones of SM.…”

“…First, we will address the comparison to the previously reported experimental results on the HF modes by Domask [13]. There, samples with thickness of 6 nm, 9 nm, and 79 nm were characterized using Raman spectroscopy at three main sample preparation steps: 1) on exfoliation of the pure MoS 2 film, 2) on deposition of the Ag-film on top of MoS 2 , and 3) after annealing for 4 hours at 400 • C at which point Ag-intercalation is assumed to have taken place.…”

“…Unfortunately, direct simulation of the experimental sample thickness is not feasible with DFT due to high computational cost, while LCM only applies to the LF interlayer modes, since it does not capture the more complicated intralayer force-constants. Thus, we can only speculate about the mechanisms taking place in the experiments of Domask [13] by examining trends of our HF-modes results in few-layer systems with increasing number of layers. As mentioned in section III, the HF modes red-shift with C Ag similar to the LF modes, but by a significantly smaller amount.…”

Enabling remote quantum emission in 2D semiconductors via porous metallic networks

“…19 Alternatively, 2DC/metal interfaces with crystallographic registry can be formed through van der Waals epitaxy. 20 During physical vapor deposition, thin metal films tend to preferentially align on 2DCs, 21,22 which results in periodic (Moiré) structural and electronic variations at the interface due to the lattice mismatch. We demonstrate a platform that brings together concepts from each of these areas: aligned 2DC/metal interfaces, SPP-exciton coupling, and 2D quantum emitters.…”

In Situ Characterization of Transformations in Nanoscale Layered Metal Chalcogenide Materials: A Review

“…The interlayer crystallographic twist across the vdW interface also allows for tuning of interlayer coupling, electronic band structure, and conductivity. [66] Growth of ultra-thin metal contacts epitaxially on MoS 2 crystals [67] can allow for improved and atomically sharp interfaces required to form transistors, while epitaxial growth of single-crystalline MCs on 2D layered substrates can enhance lateral/surface diffusion and lower the required growth temperature, making them more amenable to conventional Si fabrication techniques. [68][69][70] Multiple in situ studies have explored the growth of vdW heterostructures.…”