Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 11: Methods: Scanning probe techniques II
O 11.7: Vortrag
Montag, 22. März 2010, 16:30–16:45, H32
Infrared near-field optical microscopy on sub-surface doped silicon — •Rainer Jacob1, Manfred Helm1, Stephan Winnerl1, Harald Schneider1, Marc Tobias Wenzel2, Hans-Georg von Ribbeck2, and Lukas M. Eng2 — 1Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden, 01314 Dresden, Germany — 2Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden, Germany
Scattering-type scanning near-field optical microscopy (s-SNOM) has proven as a useful tool for surface science. Materials can be distinguished by their interaction with the local probe, hence yielding different intensities of the near-field signal. In semiconductors this can be achieved through doping, allowing a significant variation in the dielectric function. This becomes even more interesting when probing sub-surface interactions of such dopants.
Although s-SNOM is mainly used as a surface sensitive technique, we present here the ability to probe sub-surface doped silicon. To this end we prepared samples by implanting gallium and boron with different energies at a variable depth. Afterwards, the samples were annealed in order to activate the dopants. The carriers were then investigated with IR-s-SNOM using wavelengths between 9 and 15 µm from the free-electron laser at the FZD. We were able to probe doping layers up to 100 nm below the surface. Furthermore, we could show contrast inversion between doped and undoped areas in the Si-wafer for different wavelengths. From these measurements the carrier density in doped regions can be extracted directly using the Drude model.