Size and Stoichiometric Dependence of Thermal Conductivities of InxGa1-xN: A Molecular Dynamics Study

TL;DR

This study uses molecular dynamics simulations to analyze how size, temperature, and composition affect the thermal conductivity of InxGa1-xN alloys, revealing a minimum at equal In and Ga content and insights into phonon behavior.

Contribution

It provides a detailed molecular dynamics analysis of the size, temperature, and stoichiometry effects on InxGa1-xN thermal conductivity, including phonon dispersion and mean free path relationships.

Findings

Thermal conductivity decreases with increasing temperature.

Minimum thermal conductivity occurs at x ≈ 0.5 in InxGa1-xN.

Calculated k values agree with Boltzmann transport equation results.

Abstract

The thermal conductivities k of wurtzite InxGa1-xN are investigated using equilibrium molecular dynamics (MD) method. The k of InxGa1-xN rapidly declines from InN (k_InN = 141 W/mK) or GaN (k_GaN = 500 W/mK) to InxGa1-xN, and reaches a minimum (k_min = 19 W/mK) when x is around 0.5 at 300 K. The mean free path (MFP) of InxGa1-xN, ranging from 2 to 5 nm and following the same trend with the k, is extrapolated in our simulation and a parabolic relationship between x and MFP is established. We find that the k of InxGa1-xN decreases with increasing temperatures. The evolution of k of InxGa1-xN is also examined by projecting the momentum-energy relationship of phonons from MD trajectories. The phonon dispersion and phonon density of states for InxGa1-xN reflect a slightly more flattened dispersive phononic curve of the alloying system. Despite an overestimated k than experimental values, our calculated k at 300 K agrees well with the results obtained by solving Boltzmann transport equation and also has the same stoichiometric trend with the experimental data. Our study provides the coherent analysis of the effect of thickness, temperature and stoichiometric content on the thermal transport of InxGa1-xN which is helpful for the thermal management of InxGa1-xN based devices.