Ab initio study of enhanced thermal conductivity in ordered AlGaO3 alloys

Abstract

We compute the lattice thermal conductivity of monoclinic b-Ga 2 O 3 and the ordered AlGaO 3 alloy from the phonon Boltzmann transport equation, with the harmonic and third-order anharmonic force constants calculated from density functional theory. The calculated thermal conductivity of b-Ga 2 O 3 is consistent with experiment. We demonstrate that the lowest-energy structure of an Al 0:5 Ga 0:5 alloy, which is ordered, has a thermal conductivity that is raised by more than 70% compared to b-Ga 2 O 3 . We attribute the enhancement to (1) increased group velocities and (2) reduced anharmonic scattering rates due to the reduced weighted phase space. The findings offer an avenue toward improved heat dissipation from Ga 2 O 3 devices.

Effect of Titanium Induced Chemical Inhomogeneity on Crystal Structure, Electronic Structure, and Optical Properties of Wide Band Gap Ga2O3

“…To accurately model the electronic and structural properties of Ga 2 O 3 , we use the HSE06 hybrid functional, with a mixing parameter of 32%. Ga d electrons are included in the valence, as this was found to be important to accurately describe the ground state of Ga 2 O 3 and the preferential positions of Al in Ga 2 O 3 . , All atomic positions are fully relaxed so that the remaining forces are smaller than 0.01 eV/Å. Formation energies were obtained using the formalism outlined in ref ,.…”

Anomalous Temperature-Dependent Phonon Anharmonicity and Strain Engineering of Thermal Conductivity in β-Ga2O3

“…β-Ga 2 O 3 with an ultrawide band gap of 4.9 eV has a broad application prospect in gas detection, photoelectric detection, and power electronics. − However, the realization of β-Ga 2 O 3 -based high-performance devices is faced with two obstacles, including the lack of p-type β-Ga 2 O 3 materials and the low lattice thermal conductivity κ of β-Ga 2 O 3 . − For instance, low κ may induce a serious self-heating effect, leading to an increase in channel temperature, a decrease in electron mobility, and a significant decrease in the cutoff frequency as the output power increases, which seriously hinder the application of β-Ga 2 O 3 in power electronics. Therefore, the pulse signal operation in the field-plated β-Ga 2 O 3 metal oxide semiconductor field-effect transistor (MOSFET) and the integration of high-κ materials including diamond and sapphire as substrates or heat transducers are proposed to enhance the heat dissipation rate of the β-Ga 2 O 3 -based devices. − …”

Lattice thermal conductivity of β-, α- and κ- Ga2O3: a first-principles computational study

“…1,2) However, its low thermal conductivity in comparison to commonly used semiconductors such as Si, SiC, and GaN brings great challenges in thermal management and may limit its high-power applications. [3][4][5] Currently, Ga 2 O 3 is known to exist in five different crystalline phases (α-, β-, γ-, δand εor κ-), each with a bandgap value around 5 eV. 6,7) Among these phases, β-Ga 2 O 3 has a monoclinic crystal structure and is the most stable and extensively researched.…”

“…Nevertheless, there have been a few attempts using molecular dynamics simulations and firstprinciples calculations to estimate thermal conductivity values for different Ga 2 O 3 phases. 3,[24][25][26][27][28] For β-Ga 2 O 3 , there exists certain disparities between the lattice thermal conductivity obtained using different experimental and computational methods (see Table II for details). Furthermore, theoretical investigation on the thermal transport properties of α-Ga 2 O 3 and κ-Ga 2 O 3 is scarce.…”