Layer Dependence of Thermally Induced Quantum Confinement and Higher Order Phonon Scattering for Thermal Transport in CVD-Grown Triangular MoS₂

Heat dissipation and electron–phonon interaction hindering the charge carrier mobility are serious constraints for the fabrication of various integrated electronic and optoelectronic devices based on two-dimensional (2D) materials. In this paper, we examine the quantum confinement and phonon anharmonicity of different-layered MoS 2, synthesized via the chemical vapor deposition technique. We explore the contribution of spin–orbit and interlayer couplings both theoretically (first-principles density functional theory) and experimentally (Raman and photoluminescence spectroscopies). Further, we demonstrate the thermally driven layer-dependent bandgap tunability in (1L, 3L, and 5L) triangular MoS 2 grown over the SiO 2 /Si substrate. We have also scrutinized their phonon confinement behavior and thermal response in a low-temperature regime (80–300 K) using the optothermal Raman spectroscopy technique. A semiquantitative model comprising the volume and temperature effect provides insights into the nonlinear temperature-dependent phonon anharmonicity, revealing that the contribution of higher order (three) phonon scattering reduces with increasing layer numbers in MoS 2 . We further measure the interfacial thermal conductance ( g ) and thermal conductivity ( k s ) of synthesized MoS 2, and the obtained values of g (and k s ) are observed to increase (and decrease) with increasing layer number. Our study will advance the understanding of anharmonic behavior of phonons in different-layered MoS 2 nanostructures for designing MoS 2 -based next-generation devices for various applications.