Impact of electron irradiation on electron holographic potentiometry
J.B. Park1, T. Niermann1, D. Berger2, A. Knauer3 , I. Koslow3,4, M. Weyers3, M. Kneissl3,4, and M. Lehmann1
Published in:
Appl. Phys. Lett., vol. 105, no. 9, 094102 (2014).
Abstract:
While electron holography in the transmission electron microscope offers the possibility to measure maps of the electrostatic potential of semiconductors down to nanometer dimensions, these measurements are known to underestimate the absolute value of the potential, especially in GaN. We have varied the dose rates of electron irradiation over several orders of magnitude and observed strong variations of the holographically detected voltages. Overall, the results indicate that the electron beam generates electrical currents within the specimens primarily by the photovoltaic effect and due to secondary electron emission. These currents have to be considered for a quantitative interpretation of electron holographic measurements, as their negligence contributes to large parts in the observed discrepancy between the measured and expected potential values in GaN.
1 Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin, Germany
2 Technische Universität Berlin, Zentraleinrichtung für Elektronenmikroskopie, Straße des 17. Juni 135, 10623 Berlin, Germany
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
4 Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany
Copyright © 2014 AIP Publishing LLC. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the AIP Publishing LLC.
Full version in pdf-format.