Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 37: Topical Session Modern Atom Probe Tomography I - Fundamentals

MM 37.5: Vortrag

Mittwoch, 28. März 2012, 16:30–16:45, H 0107

Investigation of optical properties of Silicon under high electric field by atom probe tomography — •Laurent Arnoldi¹, Angela Vella¹, Nicolas Sevelin-Radiguet¹, Francois Vurpillot¹, Tatiana Itina², Elena Silaeva², Nikita Shcheblanov², and Bernard Deconihout¹ — ¹Groupe de Physique des Matériaux, France — ²Laboratoire Hubert Curien, France

In laser assisted atom probe, surface atoms are emitted from a tip in the form of ions by the combined action of an electrostatic standing field and a laser pulse that triggers the emission. The absorption of the light by the tip apex generates a pulse heat. Models have been proposed to explain the laser tip interaction and to evaluate the temperature rise and it spatial distribution on the specimen. In this contribution we will focus on the interaction between a silicon tip and an ultra-short laser pulse. New experimental methods to determine optical properties of the field emitter in real analysis conditions (very high electric field, cryogenic temperature) will be presented. Numerical solving of Maxwell equations allow predicting the changes of the tip's absorption when the illumination conditions are modified. These simulations incorporate the refractive index of the tip surface as derived from the calculation of the band bending effect on the surface that increases the density of free careers in the presence of the field. By comparing these simulations and experimental results, we will show that the absorption of a subwavelength tip is strongly dependent on the standing electric field applied to the sample.