Electrical and physical topography in energy-filtered photoelectron emission microscopy of two-dimensional silicon pn junctions

Maylis Lavayssière (1) , Matthias Escher (2) , Olivier Renault (1) , Denis Mariolle (1) , Nicholas Barrett (3)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
2 FOCUS GmbH
3 LENSIS - Laboratoire d'Etude des NanoStructures et Imagerie de Surface

Photoelectron emission microscopy (PEEM) is a powerful non-destructive tool for spatially resolved, spectroscopic analysis of surfaces with sub-micron chemical heterogeneities. However, in the case of micron scale patterned semiconductors, band line-ups at pn junctions have a built-in lateral electric field which can significantly alter the PEEM image of the structure with respect to its physical dimensions. Furthermore, real surfaces may also have physical topography which can reinforce or counteract the electrically induced distortion at a pn junction. We have measured the experimental PEEM image distortion at such a junction and carried out numerical simulations of the PEEM images. The simulations include energy filtering and the use of a contrast aperture in the back focal plane in order to describe the changes in the PEEM image of the junction with respect to its real physical dimensions. Threshold imaging does not give a reliable measurement of micron sized p and n type patterns. At higher take-off energies, for example using Si 2p electrons, the pattern width is closer to the real physical size. Physical topography must also be quantitatively accounted for. The results can be generalized to PEEM imaging of any structure with a built-in lateral electric field.

Mots clés: Pn junction; Photoelectron emission microscopy; Surface imaging; Simulations

Domaines: Physique [physics]

Maylis Lavayssière, Matthias Escher, Olivier Renault, Denis Mariolle, Nicholas Barrett. Electrical and physical topography in energy-filtered photoelectron emission microscopy of two-dimensional silicon pn junctions. Journal of Electron Spectroscopy and Related Phenomena, 2013, 186, pp.30 - 38. ⟨10.1016/j.elspec.2013.01.014⟩. ⟨cea-01477558⟩