Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 76: Nanostructures at surfaces IV
O 76.2: Vortrag
Donnerstag, 29. März 2012, 16:15–16:30, MA 042
Photo sensitivity and field emission properties of B-doped Si-tip arrays — •Benjamin Bornmann1, Stephan Mingels1, Aliaksandr Navitski1, Pavel Serbun1, Florian Dams2, Christian Prommesberger2, Rupert Schreiner2, Dirk Lützenkirchen-Hecht1, and Günter Müller1 — 1FB C Physics Department, University of Wuppertal, 42119, Wuppertal, Germany — 2Faculty of Microsystems Technology, University of Applied Sciences Regensburg, 93053, Regensburg, Germany
Field emission (FE) cathodes have shown significant advantages over thermionic electron sources. For sensor applications Si tips are favored because they can be easily integrated with other Si based components. p-semiconductors have a limited number of free electrons thus being highly sensitive to photonic excitation. This allows the realization of compact fast switchable e−-sources. We report on FE-spectroscopy on B-doped Si-tip arrays with optional tunable laser illumination (0.5-5.9 eV). The current-voltage curve exhibits three emission regimes: a Fowler-Nordheim regime at low currents, a saturation region due to electron depletion and secondary carrier generation at high currents. The corresponding spectra show an increased charging in saturation by a shift and splitting of the peaks. A high conductivity is observed under secondary carrier generation. The FE is most stable in saturation as the emission strongly depends on the supply function here rather than on the surface sensitive tunneling probability. Accordingly, the highest photosensitivity is observed in saturation. Optimization of the quantum efficiency with tunable laser illumination is ongoing.