HrZZ - UIP-2020-02-8891HrZZ - UIP-2020-02-8891HrZZ - UIP-2020-02-8891MOBDOL-2023-08-2165
The MOBDOL grant focuses on functionalizing TMDs with organic molecules using UHV-STM as the primary characterization tool, complemented by AFM and Raman spectroscopy under ambient conditions.
During the first mid-term period (11 months) of the grant, efforts were dedicated to establishing key experimental protocols essential for achieving the project’s final objectives in the second period. This phase included the growth of graphene-covered metal substrates—Ir(111), Ir(332), and Ni(111)—for future TMD deposition (see Figure 01). These substrates were specifically chosen to tailor the properties of the TMD layers grown on them. Once the growth protocols were established, we investigated their aging effects by storing the samples under ambient conditions for a week and subsequently analyzing them using AFM and Raman spectroscopy.
Subsequently, we have been developing molecular deposition protocols on gr/Ir(111). An example of our results is shown in Figure 02, where we demonstrate the controlled deposition and self-assembly of pentacene molecules on gr/Ir(111). These results provide a solid foundation for the upcoming TMD growth and functionalization phase in the second year.
The second period of the grant will focus on the growth of different transition metal disulfides—MoS₂, VS₂, and WS₂—initially on gr/Ir(111) and subsequently on the other two substrates. Finally, functionalization will be carried out, with molecular evaporation following the protocols that have already been developed.
Figure 01. (a) Large STM image showing different terraces and step edges of the Ir(111) crystal covered with graphene. (b) Large STM image showing the surface of a graphene-covered Ir(332) crystal, where the typical step bunching and parallel terraces are resolved. (c) Large STM image showing terraces and step edges of the Ni(111) crystal; the surface is mostly clean except for some patches of NiC₂. (d) Atomically resolved STM image of the graphene layer, where the large periodicity corresponds to that of the gr/Ir(111) moiré pattern. (e) Close-up STM image of one of the terraces of the Ir(332) crystal, where both the moiré pattern and the atomic periodicity are resolved. (f) STM image showing atomic resolution of clean Ni(111) and NiC₂, used for the Fourier analysis of the periodicities.
Figure 02. (a) STM image of the gr/Ir(111) surface with a pentacene monolayer. Molecular evaporation parameters: T = 87 °C, t = 1 min. (b) and (c) STM images showing the stripe pattern of the molecular islands. In some patches of the molecular islands, the periodicity of the underlying gr/Ir(111) moiré pattern can be observed.
MOBDOK-2023-4185
DOK-NPOO-2023-10-4241