Ultrahigh and anisotropic thermal transport in the hybridized monolayer (BC2N) of boron nitride and graphene: a first-principles study

2D Embedded Ultrawide Bandgap Devices for Extreme Environment Applications

Ultrawide bandgap semiconductors such as AlGaN, AlN, diamond, and β-Ga2O3 have significantly enhanced the functionality of electronic and optoelectronic devices, particularly in harsh environment conditions. However, some of these materials face challenges such as low thermal conductivity, limited P-type conductivity, and scalability issues, which can hinder device performance under extreme conditions like high temperature and irradiation. In this review paper, we explore the integration of various two-dimensional materials (2DMs) to address these challenges. These materials offer excellent properties such as high thermal conductivity, mechanical strength, and electrical properties. Notably, graphene, hexagonal boron nitride, transition metal dichalcogenides, 2D and quasi-2D Ga2O3, TeO2, and others are investigated for their potential in improving ultrawide bandgap semiconductor-based devices. We highlight the significant improvement observed in the device performance after the incorporation of 2D materials. By leveraging the properties of these materials, ultrawide bandgap semiconductor devices demonstrate enhanced functionality and resilience in harsh environmental conditions. This review provides valuable insights into the role of 2D materials in advancing the field of ultrawide bandgap semiconductors and highlights opportunities for further research and development in this area.

Investigation of phase transition, mechanical behavior and lattice thermal conductivity of halogen perovskites using machine learning interatomic potentials

Using a machine learning (ML) approach to fit DFT data, interatomic potentials have been successfully extracted. In this study, the phase transition, mechanical behavior and lattice thermal conductivity are investigated for halogen perovskites using NEP-based MD simulations in a large supercell including 16 000 atoms, which breaks through the size and temperature effects in DFT. A clear phase transition from orthorhombic (γ) → tetragonal (β) → cubic (α) is observed during the heating process. During the cooling process, CsPbCl3 and CsPbBr3 exhibit perfect reversible behavior, while CsPbI3 only undergoes a phase transition from α to β. Then, the key mechanical parameters, including Poisson's ratio, tensile strength, critical strain and bulk modulus, are predicted. The thermal conductivity is also investigated using the NEP-based MD simulations. At room temperature, they exhibit extremely low thermal conductivity. The predicted results are compared with the experimental results, and the rationality of ML potentials has been confirmed.

The effect of non-analytical corrections on the phononic thermal transport in InX (X = S, Se, Te) monolayers

We investigate the effect of non-analytical corrections on the phonon thermal transport properties in two-dimensional indium chalcogenide compounds. The longitudinal optical (LO) and transverse optical (TO) branches in the phonon dispersion are split near the Γ-point. The lattice thermal conductivity of monolayer InS is increased by 30.2% under non-analytical corrections because of the large LO-TO splitting at Γ-point. The predicted lattice thermal conductivities with non-analytical corrections at room temperature are 57.1 W/mK, 44.4 W/mK and 33.1 W/mK for the monolayer InS, InSe and InTe, respectively. The lattice thermal conductivity can be effectively reduced by nanostructures because the representative mean free paths are found very large in these monolayers. By quantifying the relative contribution of the phonon modes to the lattice thermal conductivity, we predict that the longitudinal acoustic branch is the main contributor to the lattice thermal conductivity. Due to the low lattice thermalconductivities of these monolayers, they can be useful in the nanoscale thermoelectric devices.

Thermal conductivity of hexagonal BC2P – a first-principles study

In this work, we report a high thermal conductivity (k) of 162 W m⁻¹ K⁻¹ and 52 W m⁻¹ K⁻¹ at room temperature, along the directions perpendicular and parallel to the c-axis, respectively, of bulk hexagonal BC₂P (h-BC₂P), using first-principles calculations.