Operational and environmental conditions regulate the frictional behavior of two-dimensional materials.

The friction characteristics of single-layer h-BN, MoS, and graphene were systematically investigated via friction force microscopy measurements at various operational (e.g., normal force and sliding speed) and environmental (e.

Layer-by-layer thinning of MoS via laser irradiation.

Layer-by-layer thinning of molybdenum disulfide (MoS) via laser irradiation was examined using Raman spectroscopy and atomic force microscopy. In particular, the effects of number of layers, laser conditions, and substrate were systematically identified. The results demonstrated the presence of nanoparticles on the MoS at sufficient laser treatment conditions prior to layer-by-layer thinning.

Surface Properties of Laser-Treated Molybdenum Disulfide Nanosheets for Optoelectronic Applications.

Transition metal dichalcogenide two-dimensional materials have attracted significant attention due to their unique optical, mechanical, and electronic properties. For example, molybdenum disulfide (MoS) exhibits a tunable band gap that strongly depends on the numbers of layers, which makes it an attractive material for optoelectronic applications. In addition, recent reports have shown that laser thinning can be used to engineer an MoS monolayer with specific shapes and dimensions.

Interfacial Strength and Surface Damage Characteristics of Atomically Thin h-BN, MoS, and Graphene.

Surface damage characteristics of single- and multilayer hexagonal boron nitride (h-BN), molybdenum disulfide (MoS), and graphene films were systematically investigated via atomic force microscopy (AFM)-based progressive-force and constant-force scratch tests and Raman spectroscopy. The film-to-substrate interfacial strengths of these atomically thin films were assessed based on their critical forces (i.e.

Growth and Simultaneous Valleys Manipulation of Two-Dimensional MoSe-WSe Lateral Heterostructure.

The covalently bonded in-plane heterostructure (HS) of monolayer transition-metal dichalcogenides (TMDCs) possesses huge potential for high-speed electronic devices in terms of valleytronics. In this study, high-quality monolayer MoSe-WSe lateral HSs are grown by pulsed-laser-deposition-assisted selenization method. The sharp interface of the lateral HS is verified by morphological and optical characterizations.

Quantitative Assessment of Friction Characteristics of Single-Layer MoS2 and Graphene Using Atomic Force Microscopy.

Atomically thin layered materials such as MoS2 and graphene have attracted a lot of interest as protective coating layers for micro- and nano-electromechanical devices based on their superior mechanical properties and chemical inertness. In this work, the frictional characteristics of single layer MoS2 and graphene prepared by the mechanical exfoliation method were quantitatively investigated using atomic force microscopy. The results showed that both MoS2 and graphene exhibited relatively low friction forces of 1-3 nN under normal forces ranging from 1 to 30 nN.

Laser-Induced Particle Adsorption on Atomically Thin MoS2.

Atomically thin molybdenum disulfide (MoS2) shows great potential for use in nanodevices because of its remarkable electronic, optoelectronic, and mechanical properties. These material properties are often dependent on the thickness or the number of layers, and hence Raman spectroscopy is widely used to characterize the thickness of atomically thin MoS2 due to the sensitivity of the vibrational spectrum to thickness. However, the lasers used in Raman spectroscopy can increase the local surface temperature and eventually damage the upper layers of the MoS2, thereby changing the aforementioned material properties.

Quantitative assessment of contact and non-contact lateral force calibration methods for atomic force microscopy.

Atomic Force Microscopy (AFM) has been widely used for measuring friction force at the nano-scale. However, one of the key challenges faced by AFM researchers is to calibrate an AFM system to interpret a lateral force signal as a quantifiable force. In this study, five rectangular cantilevers were used to quantitatively compare three different lateral force calibration methods to demonstrate the legitimacy and to establish confidence in the quantitative integrity of the proposed methods.