Gallium arsenide is the second most used semiconductor material with applications in light-emitting diodes, field-effect transistors, and integrated circuits. Thus, understanding and controlling the thermal conductivity of gallium arsenide is crucial to design devices for such applications. The goal of this study is to predict the thermal conductivity of gallium arsenide as a function of temperature and vacancy concentration. Thermal conductivities are predicted using an equilibrium molecular dynamics method based on the Green-Kubo formalism with temperatures between 300 K and 900 K and vacancy concentrations up to 0.5%. Our results show that the thermal conductivities of the vacancy-free system predicted by our model are in good agreement with experimental values around the Debye temperature. In addition, our model predicts that conductivities significantly decrease with increasing vacancy concentration. At 300 K conductivities drop by 39.5% with a 0.1% defect content and 74.4% with 0.5% respect to that of the pure system. The power spectra of thermal conductivities and heat current autocorrelation functions indicate that phonon scattering produced near the vacancies reduces the contribution of the acoustic frequencies. The density of states quantifies the decrease of acoustic and optic frequencies by increasing the vacancy concentration.

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