No abstract

Advanced semiconductor superlattices play important roles in critical future high-tech applications such as aerospace, high-energy physics, gravitational wave detection, astronomy, and nuclear related areas. Under such extreme conditions like high irradiative environments, these semiconductor superlattices tend to generate various defects that ultimately may result in the failure of the devices. However, in the superlattice like GaAs/AlAs, the phase stability and impact on the device performance of point defects are still not clear up to date. The present calculations show that in GaAs/AlAs superlattice, the antisite defects are energetically more favorable than vacancy and interstitial defects. The AsX (X = Al or Ga) and XAs defects always induce metallicity of GaAs/AlAs superlattice, and GaAl and AlGa antisite defects have slight effects on the electronic structure. For GaAs/AlAs superlattice with the interstitial or vacancy defects, significant reduction of band gap or induced metallicity is found. Further calculations show that the interstitial and vacancy defects reduce the electron mobility significantly, while the antisite defects have relatively smaller influences. The results advance the understanding of the radiation damage effects of the GaAs/AlAs superlattice, which thus provide guidance for designing highly stable and durable semiconductor superlattice based electronic and optoelectronics for extreme environment applications.

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No abstract

In this study, the low energy radiation responses of AlAs, GaAs and GaAs/AlAs superlattice are simulated and the radiation damage effects on their electronic structures are investigated. It is found that the threshold displacement energies for AlAs are generally larger than those for GaAs, i.e., the atoms in AlAs are more difficult to be displaced than those in GaAs under radiation environment. As for GaAs/AlAs superlattice, the Ga and Al atoms are more susceptible to the radiation than those in the bulk AlAs and GaAs, whereas the As atoms need comparable or much larger energies to be displaced than those in the bulk states. The created defects are generally Frenkel pairs, and a few antisite defects are also created in the superlattice structure. The created defects are found to have profound effects on the electronic properties of GaAs/AlAs superlattice, in which charge transfer, redistribution and even accumulation take place, and band gap narrowing and even metallicity are induced in some cases. This study shows that it is necessary to enhance the radiation tolerance of GaAs/AlAs superlattice to improve their performance under irradiation.