NanoESCA expanded to high energies:
HAXPEEM

Hard x-ray photoemission spectroscopy (HAXPES) is already a well proven technique for bulk sensitive photo-emission [1] due to the large information depth of the high energetic electrons. To extend this technique for laterally structured samples, the NanoESCA [2], up to now used for imaging XPS, k-space imaging or workfunction mapping, has been upgraded to be used for hard x-ray photoemission electron microscopy (HAXPEEM) with kinetic energies up to 10 keV [3,6].

For the high kinetic energy the extraction voltage has been raised to 24keV to enable an easy sample biasing scheme. Image stacks or spectra can be acquired continuously from threshold photoemission towards 10keV. A simple model predicts the change of magnification with kinetic energy, that is confirmed by simulations. During an energy scan the focusing of the objective lens is maintained automatically using look-up tables and focusing parameters obtained using threshold imaging.

First results were obtained during a beamtime at PETRA III [3] using a checkerboard-patterned Au/Si sample (“Chessy”) imaged on Gold and Silicon core level peaks with an electron kinetic energy of up to 6.43keV.

The results proof the the sub-micron resolution even at very high energies and for long acquisition times and the feasibility of bulk sensitive imaging using using hard x-ray excitation.
Please refer to the related
flyer for more detailed informations.

References

[1] C.Fadley, “X-ray photoelectron spectroscopy: Progress and perspectives”, J. Electron Spectrosc. Relat. Phenom. 178-179, 2 (2010)
[2] M.Escher, K.Winkler, O.Renault, N.Barrett, “Applications of high lateral and energy resolution imaging XPS with a double hemispherical analyser based spectromicroscope”, J. Electron Spectrosc. Relat. Phenom. 178-179, 303 (2010)
[3] C.Wiemann, M.Patt, S.Cramm, M.Escher, M.Merkel, A.Gloskovskii, S.Thiess, W.Drube and C.M.Schneider, “Probing buried layers by photoelectron spectroscopy with hard x-ray excitation”, Appl. Phys. Lett. 100, 223106 (2012)
[4] C.Wiemann, M.Patt, I.P.Krug, N.B.Weber, M.Escher, M.Merkel and C.M.Schneider, “A new Nanospectroscopy tool with synchrotron radiation: NanoESCA@Elettra”, e-J. Surf. Sci. Nanotech. 9, 395-399 (2011)
[5] S.Tanuma, C.J.Powell, D.R.Penn, “Calculations of electron inelastic mean free paths”. Surf. Interface Anal. 43, 689-713 (2011)
[6] M.Patt, C.Wiemann, N.B.Weber, M.Escher, A.Gloskovskii, W.Drube, M.Merkel, C.M.Schneider, Rev. Sci. Instrum., 85, 1137 (2014)



HAXPEEM_Flyer_2015_Seite_2


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