Ab initio molecular dynamics simulation of the radiation damage effects of GaAs/AlGaAs superlattice

In the past several decades, the radiation tolerance of semiconductor superlattices has been extensively investigated to improve their performance under radiation environment. In the literature, it has been reported that the GaAs/AlGaAs superlattice is more radiation resistant than the GaAs/AlAs superlattice; however, the underlying physical origin still remains unknown. In this study, an ab initio molecular dynamics simulation of low-energy radiation response of the GaAs/AlGaAs superlattice confirms the experimental observation that the radiation resistance of GaAs/AlAs suplerlattice is enhanced by the introduction of Ga to AlAs layer. Also, it turns out that a large number of antisite defects are created during the dynamic process of the displacement events for the GaAs/AlGaAs superlattice. These antisite defects have low formation energies and increase the energy barrier for further defect generation, thus resulting in enhanced radiation tolerance. The presented results unveil the underlying mechanism for the enhanced radiation tolerance induced by introducing Ga to AlAs layer in the GaAs/AlAs superlattice, which will be beneficial to design highly radiation-resistant semiconductor superlattices for their applications as optical and electronic devices.