Atom Probe Tomography for Dynamic Characterization of Materials Surface Phenomena

Atom Probe Tomography (APT) is a microscopy and micro-analysis technique based on field ion evaporation. Its standard application to materials science yields a <i>static</i> <i>picture</i> of a system, providing a set of 3D reconstructed positions of ions chemically identified through their mass/charge ratio. However, field ion evaporation is a complex<i> dynamic process</i>, driven by the system chemistry and by environmental parameters such as temperature, electric field, intensity and wavelength of laser pulses [1]. The correlated evaporation of spatially neighboring atoms, the formation and evaporation of molecular ions either through surface dynamics or through the interaction of residual gas molecules and the surface, the dissociation of molecular ions are examples of processes that occur and carry specific traces in APT datasets. This information is typically neglected in APT analysis, but may give important insight about surface chemistry under high field (with or without laser illumination), which makes of APT a technique for <i>dynamic studies</i> of material surfaces.<br/>In this contribution several examples of a dynamic use of APT will be reported: (i) the formation of molecular ions in silicon carbide, with its consequences on spatial and compositional accuracy of APT reconstructions[2], (ii) the microscopic assessment of single reactions involving molecular hydrogen adsorbed at the surface of III-N materials [3] and (iii) the field-dependent formation of hydride molecules in III-N materials.<br/>The perspective extension of these dynamic APT approaches to other materials and surface chemical reactions will finally be discussed.<br/><br/>[1] M. K. Miller et R. G. Forbes, « Introduction to the Physics of Field Ion Emitters », in <i>Atom-Probe Tomography</i>, Springer, Boston, MA, 2014, p. 51. doi: 10.1007/978-1-4899-7430-3_2.<br/>[2] S. Ndiaye, C. Bacchi, B. Klaes, M. Canino, F. Vurpillot, et L. Rigutti, « Surface Dynamics of Field Evaporation in Silicon Carbide », <i>J. Phys. Chem. C</i>, vol. 127, n^o 11, p. 5467, mars 2023, doi: 10.1021/acs.jpcc.2c08908.<br/>[3] L. Rigutti <i>et al.</i>, « Surface Microscopy of Atomic and Molecular Hydrogen from Field-Evaporating Semiconductors », <i>J. Phys. Chem. C</i>, vol. 125, n^o 31, p. 17078, août 2021, doi: 10.1021/acs.jpcc.1c04778.