Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 43: Poster Session: Quantum Dots and Wires - Preparation and Characterization / Devices (incl. Laser) / Ultrafast Phenomena

HL 43.15: Poster

Dienstag, 27. März 2012, 09:30–12:30, Poster D

Measurement of electrostatic potential at group III-N semiconductors using electron holography — •Jae Bum Park, Tore Niermann, and Michael Lehmann — Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany

Off-axis electron holography (EH) allows acquiring the whole information of the electron wave, i.e. amplitude and phase, the latter is usually lost. The phase of the electron wave is sensitive to electrostatic potential variation due to doping profiles from pn-junctions and piezoelectric fields at quantum wells. We employ this interference technique on group III-N semiconductor heterostructures. Because the phase of the electron wave is also affected by the specimen thickness, thickness measurement approaches like dark field imaging (DF) and convergent beam electron diffraction (CBED) are applied. However, the determined potentials from measured phase information normally show a discrepancy from the expected one. Additionally the surface depletion effect must be taken into account for quantitative analysis of the electrostatic potential from the reconstructed phase. This research is performed to investigate the influence of these effects on the observed mismatch of the potential. This work is carried out within the DFG collaborative research center CRC 787 Nanophotonik.