中子嬗变掺杂前后Ge纳米晶的结构和性质

采用第一性原理计算模拟Ge纳米晶在中子嬗变掺杂(NTD)后受空位、O和As杂质的影响.结果表明,退火方法引入的O并不能消除纳米晶中的辐照致空位缺陷的影响,而NTD 产生的As掺杂能补偿这些空位缺陷并消除禁带中产生的杂质能级,从而改善半导体掺杂性能.计算还发现,由于较高的电负性,纳米晶中O对Ge原子较强的吸附作用阻止了空位的形成,导致与缺陷相关的非辐射发光中心的浓度减小,发光效率提高,因此中子辐照掺杂前的高温退火处理是非常有必要的.计算较好地解释了已报道的实验结果. 关键词： Ge纳米晶 中子嬗变掺杂 第一性原理 空位缺陷

The structures and properties of Ge nanocrystals before and after Neutron transmutation doping

The effects of vacant, O defects and As doping on the structures and properties of Ge nanocrystals (Ge-ncs) are investigated by using first-principles calculation based on the density functional theory (DFT). The calculation results indicate that the O defects induced by thermal annealing cannot compensate for the defects caused by neutron irradiation in Ge nanocrystals, while the introduction of As produced by neutron transmutation doping (NTD) will do the jop. We also show that the strong attraction between O and Ge atoms inhibits the formation of vacant defects in Ge nanocrystals, and further improve the luminescent property of Ge-SiO₂ system. This suggests that it is necessary to perform thermal annealing for Ge-ncs structures before NTD. Our calculations well support our previous experimental results.