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 .

Molybdenum disulfide is a layered transition-metal dichalcogenide semiconductor that is attracting renewed attention for its potential use in future nanoscale electronics, optoelectronics, catalysis, tribology, and other fields. In all of these cases, the interaction between MoS 2 and various transition metals is very important. In this work we survey the thermodynamics of the metal-Mo-S systems and the anticipated reaction products from transition metals and MoS 2 . We examined over 200 references on the reactions between transitions metals (M) and MoS 2 , compiled thermodynamic data, and used the thermodynamic data to predict M-Mo-S ternary phase diagrams for systems without experimentally determined diagrams. Where possible, experimental literature on the interactions between metals and MoS 2 was used to corroborate our predicted diagrams and stable reaction products. Both the previously reported and newly predicted M-Mo-S phase diagrams fall into three categories. In the first category, the metal is in thermodynamic equilibrium with MoS 2 . In another, there is a driving force for the metal to reduce MoS 2 , with tie lines to sulfides of the contact metal dominating the phase diagram. In a final category, there is a very stable solid solution or ternary phase that dominates the phase diagram. Better understanding of the phase equilibria in the M-Mo-S systems will aid research on the use of MoS 2 in a variety of fields.

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Motivated by interest in contacts to the layered semiconductor WS 2 , this study investigates condensed phase equilibria in M-W-S systems (M = transition or post-transition metal) and relates the findings to earlier work on M-Mo-W systems. Thermodynamic data were collected or estimated for the binary phases bearing M, W, and/or S; and a literature search for existing ternary phases was performed.Condensed phase M-W-S isothermal phase diagrams were calculated where sufficient data was available.These phase diagrams reflected three general forms. The early transition metals and group 13 posttransition metals were mostly reactive with WS 2 , with the resulting diagrams being either metal sulfide dominant or ternary/solid solution dominant. The late transition metals were all WS 2 dominant, where the metal is in equilibrium with WS 2 . These findings are similar to those from our earlier study on the M-Mo-S phase diagrams and can be used to guide studies on contacts to WS 2 .