School of Physics, University of Electronic Science and Technology of China, Chengdu, 610054, China.
Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang, 621900, China.
Sci Rep. 2018 Jan 31;8(1):2012. doi: 10.1038/s41598-018-20155-0.
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.
在这项研究中，模拟了 AlAs、GaAs 和 GaAs/AlAs 超晶格的低能辐射响应，并研究了辐射对它们电子结构的破坏效应。结果发现，AlAs 的阈位移能通常大于 GaAs 的阈位移能，即在辐射环境下，AlAs 中的原子比 GaAs 中的原子更难被位移。对于 GaAs/AlAs 超晶格，Ga 和 Al 原子比体相 AlAs 和 GaAs 中的原子更容易受到辐射，而 As 原子需要相当或更大的能量才能被位移，这比体相状态中的原子更难被位移。所产生的缺陷通常是弗伦克尔对，在超晶格结构中也会产生一些反位缺陷。研究发现，所产生的缺陷对 GaAs/AlAs 超晶格的电子性质有深远的影响，其中会发生电荷转移、重新分布甚至积累，在某些情况下会导致带隙变窄甚至金属化。本研究表明，需要提高 GaAs/AlAs 超晶格的抗辐射能力，以改善其在辐照下的性能。
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