A First-Principles Study of the Thermodynamic Properties of GaAs under Intense Electronic Excitation

In this paper, we present the phonon dispersion curves of Gallium arsenide (GaAs) at different electronic temperatures. Based on the phonon spectra, we further investigated the thermodynamic properties of GaAs under intense electronic excitation. The phonon entropy, phonon heat capacity and phonon contribution to the Helmholtz free energy and the internal energy as functions of temperature at different electronic temperatures are calculated. A sudden change in the phonon entropy-temperature curve from Te = 1.25 to 1.5 eV provides an indication of GaAs undergoing a phase transition from a solid to a liquid. This can be considered as collateral evidence for the non-thermal melting of GaAs under electronic excitation.