Versatile recognition of graphene layers from optical images under controlled illumination through green channel correlation method.

In this study, a simple yet versatile method is proposed for identifying the number of exfoliated graphene layers transferred on an oxide substrate from optical images, utilizing a limited number of input images for training, paired with a more traditional number of a few thousand well-published Github images for testing and predicting. Two thresholding approaches, namely the standard deviation-based approach and the linear regression-based approach, were employed in this study. The method specifically leverages the red, green, and blue color channels of image pixels and creates a correlation between the green channel of the background and the green channel of the various layers of graphene.

CVD Synthesis of MoS Using a Direct MoO Precursor: A Study on the Effects of Growth Temperature on Precursor Diffusion and Morphology Evolutions.

In this study, the influence of growth temperature variation on the synthesis of MoS using a direct MoO precursor was investigated. The research showed that the growth temperature had a strong impact on the resulting morphologies. Below 650 °C, no nucleation or growth of MoS occurred.

Signatures of hot carriers and hot phonons in the re-entrant metallic and semiconducting states of Moiré-gapped graphene.

Stacking of graphene with hexagonal boron nitride (h-BN) can dramatically modify its bands from their usual linear form, opening a series of narrow minigaps that are separated by wider minibands. While the resulting spectrum offers strong potential for use in functional (opto)electronic devices, a proper understanding of the dynamics of hot carriers in these bands is a prerequisite for such applications. In this work, we therefore apply a strategy of rapid electrical pulsing to drive carriers in graphene/h-BN heterostructures deep into the dissipative limit of strong electron-phonon coupling.

CVD Synthesis of Intermediate State-Free, Large-Area and Continuous MoS via Single-Step Vapor-Phase Sulfurization of MoO Precursor.

The low evaporation temperature and carcinogen classification of commonly used molybdenum trioxide (MoO) precursor render it unsuitable for the safe and practical synthesis of molybdenum disulfide (MoS). Furthermore, as evidenced by several experimental findings, the associated reaction constitutes a multistep process prone to the formation of uncontrolled amounts of intermediate MoSO phase mixed with the MoS crystals. Here, molybdenum dioxide (MoO), a chemically more stable and safer oxide than MoO, was utilized to successfully grow cm-scale continuous films of monolayer MoS.

Versatile, Low-Cost, and Portable 2D Material Transfer Setup with a Facile and Highly Efficient DIY Inert-Atmosphere Glove Compartment Option.

Research in van der Waals heterostructures has been rapidly progressing in the past decade, thanks to the art of sequential and deterministic placement of one two-dimensional (2D) material over another. The successful creation of heterostructures however has relied largely on expensive transfer systems that are not easily accessible to researchers. Although a few reports on low-cost systems have recently surfaced, the full functionality, portability features, and overall effectiveness of such systems are still being explored.

Transient Response of h-BN-Encapsulated Graphene Transistors: Signatures of Self-Heating and Hot-Carrier Trapping.

We use transient electrical measurements to investigate the details of self-heating and charge trapping in graphene transistors encapsulated in hexagonal boron nitride (h-BN) and operated under strongly nonequilibrium conditions. Relative to more standard devices fabricated on SiO substrates, encapsulation is shown to lead to an enhanced immunity to charge trapping, the influence of which is only apparent under the combined influence of strong gate and drain electric fields. Although the precise source of the trapping remains to be determined, one possibility is that the strong gate field may lower the barriers associated with native defects in the h-BN, allowing them to mediate the capture of energetic carriers from the graphene channel.

Conductance fluctuations in graphene in the presence of long-range disorder.

The fluctuations in the conductance of graphene that arise from a long-range disorder potential induced by random impurities are investigated with an atomic tight-binding lattice. The screened impurities lead to a slow variation of the background potential and this varies the overall potential landscape as the Fermi energy or an applied magnetic field is varied. As a result, the phase interference varies randomly and leads to fluctuations in the conductance.