The European Physical Journal D ( IF 1.5 ) Pub Date : 2021-07-15 , DOI: 10.1140/epjd/s10053-021-00215-3 Lorenzo Stella 1, 2 , Jonathan Smyth 1 , Jorge Kohanoff 1, 3 , Brendan Dromey 4
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Abstract
The relaxation of free electron–hole pairs generated after proton irradiation is modelled by means of a simplified set of hydrodynamic equations. The model describes the coupled evolution of the electron–hole pair and self-trapped exciton (STE) densities, along with the electronic and lattice temperatures. The equilibration of the electronic and lattice excitations is based on the two-temperature model, while two mechanisms for the relaxation of free electron–hole pairs are considered: STE formation and Auger recombination. Coulomb screening and band gap renormalisation are also taken into account. Our numerical results show an ultrafast (\({\ll }\,{\mathrm {1}}\) ps) free electron–hole pair relaxation time in amorphous \({{\mathrm {SiO}}_{\mathrm {2}}}\) for initial carrier densities either below or above the exciton Mott transition. Coulomb screening alone is not found to yield the long relaxation time (\({\mathrm {\gg }}{\mathrm {10}}\) ps) experimentally observed in amorphous \({{\mathrm {SiO}}_{\mathrm {2}}}\) and borosilicate crown glass BK7 irradiated with high-intensity laser pulses or BK7 irradiated by short proton pulses. Another mechanism, e.g. thermal detrapping of STEs, is required to correctly model the long free electron–hole pair relaxation time observed experimentally.
Graphical Abstract
中文翻译：
质子辐照绝缘体中电子-空穴等离子体弛豫的激子模型
摘要
质子辐照后产生的自由电子-空穴对的弛豫通过一组简化的流体动力学方程进行建模。该模型描述了电子-空穴对和自陷激子 (STE) 密度的耦合演化，以及电子和晶格温度。电子和晶格激发的平衡基于双温度模型，同时考虑了两种自由电子 - 空穴对弛豫的机制：STE形成和俄歇复合。库仑筛选和带隙重整化也被考虑在内。我们的数值结果显示了在非晶态\({{\mathrm {SiO}}_{\mathrm {} 中的超快 ( \({\ll }\,{\mathrm {1}}\) ps) 自由电子 - 空穴对弛豫时间2}}}\)对于低于或高于激子莫特跃迁的初始载流子密度。没有发现单独的库仑筛选会产生长弛豫时间（\({\mathrm {\gg }}{\mathrm {10}}\) ps）在无定形\({{\mathrm {SiO}}_{ \mathrm {2}}}\)和高强度激光脉冲照射的硼硅酸盐冠玻璃 BK7 或短质子脉冲照射的 BK7。另一种机制，例如STE 的热解陷，需要正确模拟实验观察到的长自由电子 - 空穴对弛豫时间。
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