AI 中文总结
本研究通过第一性原理模拟，揭示受限分子H₂可参与硅缺陷的去钝化与再钝化，其双氢路径在能量和动力学上具竞争力，为相关过程提供原子级解释。
AI 中文摘要
氢对硅悬挂键的钝化是硅基光电子技术（尤其是太阳能电池）的关键需求。近期对硅异质结太阳能电池的强光浸泡实验揭示了氢钝化的有趣动力学特征，这些特征与Si-H键的断裂和再钝化相关，这些过程主要发生在非晶/晶态界面附近的多孔区域，氢在该区域可呈分子形式存在。本研究探讨分子H₂是否直接参与Si-H的去钝化和再钝化过程。我们采用密度泛函理论计算并对比点缺陷、多空位腔及Si(100)表面的形成能，以确定相关的钝化和去钝化状态；此外，我们使用弹性能带 nudged elastic band 计算确定对应路径的活化能垒。研究发现，充足的局部自由体积可通过形成受限分子H₂实现直接双氢去钝化路径，尽管该过程涉及两个Si-H键的断裂，但在能量和动力学上可与单氢路径竞争，且在p型条件下，其反向再钝化能垒低至0.15 eV。这些发现为非晶/晶态硅界面附近多孔区域在光浸泡和光照退火过程中的钝化恢复提供了合理的原子级解释。
英文摘要
The passivation of silicon dangling bonds by hydrogen is a crucial requirement for silicon-based optoelectronic technology, especially for solar cells. Recent experiments on intense light soaking of silicon heterojunction solar cells unveiled interesting dynamical aspects of hydrogen passivation that are linked to Si-H bond breaking and repassivation. These processes take place predominantly in porous regions near the amorphous/crystalline interface, where hydrogen can exist in molecular form. This work addresses the question of whether molecular H$_2$ directly participates in Si-H depassivation and repassivation. Using density functional theory, we calculate and compare formation energies of point defects, multivacancy cavities and the Si(100) surface to identify relevant passivated and depassivated states. Furthermore, we employ nudged elastic band calculations to determine the activation barriers of the corresponding pathways. We find that sufficient local free volume enables a direct double-H pathway for depassivation through the formation of confined molecular H$_2$. Despite involving the breaking of two Si-H bonds, the double-H process can be energetically and kinetically competitive with the single-H process and can exhibit a reverse repassivation barrier as low as $0.15\,$eV under p-type conditions. These findings provide a plausible atomistic explanation for passivation recovery during light soaking and illuminated annealing in porous regions near amorphous/crystalline silicon interfaces.
Comments17 pages, 10 figures
