Xia Yu
The State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China.
Ultramicroscopy. 2019 Jan;196:121-128. doi: 10.1016/j.ultramic.2018.10.004. Epub 2018 Oct 18.
Current issues associated with laser-assisted atom probe tomography of insulators are addressed by investigating laser-induced carrier dynamics and field evaporation kinetics. It is shown that for typical insulators with slow carrier recombination compared to the sub-picosecond laser pulse, hole accumulation at the surface plays a key role. By carrying out density functional theory calculations on a MgO cluster, it is found that the critical evaporation field strength decreases linearly as the surface hole density increases. This phenomenon can be explained by the hole-induced electric field. The evaporation of neutral oxygen is enhanced at low electrostatic field strength and high laser intensity. Theoretical insight is also provided for the non-stoichiometry problem in the mass spectra measured in atom probe tomography of compounds.
通过研究激光诱导的载流子动力学和场蒸发动力学，解决了与绝缘体的激光辅助原子探针层析成像相关的当前问题。结果表明，对于与亚皮秒激光脉冲相比载流子复合较慢的典型绝缘体，表面空穴积累起着关键作用。通过对MgO团簇进行密度泛函理论计算，发现临界蒸发场强随表面空穴密度的增加而线性降低。这种现象可以用空穴诱导电场来解释。在低静电场强和高激光强度下，中性氧的蒸发增强。还为化合物原子探针层析成像中质谱测量的非化学计量问题提供了理论见解。
