Nitrogenation of microscopic MoS2 surfaces by oxidation scanning probe lithography

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Molybdenum disulfide (MoS2) exhibits unique properties valuable in optoelectronics, energy harvesting, and catalysis.
• Material properties of MoS2 can be modulated through thermal oxidation and plasma treatments.
• Direct functionalization of MoS2 under ambient conditions is desirable for scalable applications.

Purpose of the Study:

• To investigate the capability of oxidation scanning probe lithography (o-SPL) for direct nitrogenation of MoS2.
• To explore the effects of varying input voltages during o-SPL on MoS2 modification.
• To characterize the chemical and topographical changes induced by o-SPL on MoS2.

Main Methods:

• Utilized oxidation scanning probe lithography (o-SPL) under ambient conditions.
• Employed Kelvin probe force microscopy (KPFM) for surface potential analysis.
• Applied Auger electron spectroscopy (AES) for elemental composition analysis.
• Investigated MoS2 samples with and without pre-oxidation treatments.

Main Results:

• High input voltage o-SPL simultaneously oxidized and nitrogenized MoS2, incorporating O and N atoms by replacing S atoms.
• High voltage o-SPL induced significant surface topographical changes, primarily due to sample delamination.
• Low input voltage o-SPL resulted in topographical changes associated with desulfurization, without oxidation or nitrogenation.
• Pre-oxidized MoS2 samples subjected to high voltage o-SPL showed nitrogenation alongside oxidation.

Conclusions:

• o-SPL is a viable technique for direct nitrogenation and oxidation of MoS2 under ambient conditions.
• The extent of MoS2 modification (nitrogenation, oxidation, desulfurization) is controllable via input voltage.
• o-SPL offers a pathway for tuning MoS2 properties for advanced material applications.