Energy and Charge Transport in 2D Atomic Layer Materials: Raman-Based Characterization

Abstract

As they hold extraordinary mechanical and physical properties, two-dimensional (2D) atomic layer materials, including graphene, transition metal dichalcogenides, and MXenes, have attracted a great deal of attention. The characterization of energy and charge transport in these materials is particularly crucial for their applications. As noncontact methods, Raman-based techniques are widely used in exploring the energy and charge transport in 2D materials. In this review, we explain the principle of Raman-based thermometry in detail. We critically review different Raman-based techniques, which include steady state Raman, time-domain differential Raman, frequency-resolved Raman, and energy transport state-resolved Raman techniques constructed in the frequency domain, space domain, and time domain. Detailed outlooks are provided about Raman-based energy and charge transport in 2D materials and issues that need special attention.

Review on Techniques for Thermal Characterization of Graphene and Related 2D Materials

“…This leads to the different stress effects in the graphene during the calibration process and experiment. Thus, the temperature probed by Raman spectroscopy is not precise, which further introduces uncertainty into κ determination [28]. Apart from this, the Raman spectroscopy actually detects the temperature of the optical phonons, which is easily affected by the thermomechanical stress.…”

“…In most research about the energy transport in 2D materials by Raman spectroscopy, the hot carrier diffusion effect is not considered, which is more prominent as the laser spot size is smaller than 0.5 µm [28]. Here, we look at a MoS 2 /c-Si structure and discuss what will happen after the laser illumination on the sample.…”

Interaction energy and isosteric heat of adsorption between hydrogen and magnesium diboride

“…The integrated effect of van der Waals and electrostatic attraction present in layered materials' intra-and inter-layer interactions have been significantly studied recently, demonstrating that the calculation of surface charge cannot be omitted. 58,59 The intercalation process, which is enabled in layered materials, can potentially weaken the intralayer interaction by disturbing the electron sharing between Mg and B atoms, thereby easing delamination. 60 Analytical study: isosteric heat of adsorption Calculation of the Henry's law constant enabled fitting to a linear function: 19) can be written as:…”

Robust and high-sensitivity thermal probing at the nanoscale based on resonance Raman ratio (R3)

“…This normalization process eliminates the effects of laser absorption coefficient and Raman shift temperature coefficient measurements. Then, the theoretical Raman intensity weighted average temperature rise under each state is calculated using a three-dimensional (3D) numerical method to determine the theoretical Θ, compare it against the experimental result, and determine a specific property, such as k or hot carrier diffusion coefficient (D) [18,19].…”