Toward the Growth of an Aligned Single-Layer MoS₂ Film

Abstract

Molybdenum disulfide (molybdenite) monolayer islands and flakes have been grown on a copper surface at comparatively low temperature and mild conditions through sulfur loading of the substrate using thiophenol (benzenethiol) followed by the evaporation of Mo atoms and annealing. The MoS(2) islands show a regular Moiré pattern in scanning tunneling microscopy, attesting to their atomic ordering and high quality. They are all aligned with the substrate high-symmetry directions providing for rotational-domain-free monolayer growth.

An MoSx Structure with High Affinity for Adsorbate Interaction

“…[6][7][8] We have recently developed a technique for growing MoS 2 -by evaporating molybdenum on a sulfur-preloaded Cu(111) surface-that leads to epitaxial MoS 2 islands of sizes ranging from approximately 1 to 100 nm and for which we have confirmed the presence of the brim state. [9] Herein, we demonstrate that another novel MoS x structure, reproducibly formed in the same fashion as in the growth of MoS 2 we recently performed, is stable in the entire temperature range of our experiments (25 K to 650 K) and reverts to its pristine form after exposure to oxygen-containing adsorbates upon annealing. More importantly, this structure interacts far more strongly with these adsorbates than MoS 2 .…”

“…We note that surrounding the MoS 2 islands we frequently found sulfur depletion of the ffiffi ffi 7 p structure. [9] This is, however, not the case around the Mo 2 S 3 islands, in agreement with their lower sulfur surface density (Figure 1 d). …”

“…All MoS 2 films and islands were found to align with the crystallographic axes of the substrate, and they appear in STM with a characteristic MoirØ pattern caused by the epitaxial growth of (4 4) unit cells of MoS 2 on (5 5) atoms of the Cu(111) substrate (Figure 1 b). [9] These islands also feature the electronic brim state, described in detail by Besenbacher and co-workers for MoS 2 synthesis on gold, [8,13] to which the catalytic activity of MoS 2 has been attributed.…”

Two-dimensional inorganic analogues of graphene: transition metal dichalcogenides

“…However, both single-and few-layer MoS 2 coexist on the substrates due to the challenge of forming a uniform metal thin film. On the other hand, single-layer MoS 2 is obtained if S instead of Mo is preloaded on a Cu surface such that the sulfur source is available only to generate the first MoS 2 monolayer [43]. Wafer-scale uniform MoS 2 thin films with controlled thickness have been grown by layer-by-layer sulfurization of a MoO 3 thin layer.…”

Single layer MoS2on the Cu(111) surface: First-principles electronic structure calculations

“…This result agrees very well with the size of Moiré unit cell observer in a recent STM experiment. 9 The two nearestsized supercells to the preferred one, (5 × 5) MoS 2 on (6 × 6) Cu(111) and (3 × 3) MoS 2 on (4 × 4) Cu(111), have m of 3.2% and −7.2%, respectively. Interestingly, several other close packed metal surfaces offer an even smaller value of m for a MoS 2 layer.…”