Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 46: III-V semiconductors: mainly wires and dots
HL 46.5: Talk
Tuesday, March 12, 2013, 16:00–16:15, H15
Imaging the local density of free charge carriers in doped InAs nanowires — •Benedikt Hauer1, Kamil Sladek2, Fabian Haas2, Thomas Schäpers2, Hilde Hardtdegen2, and Thomas Taubner1 — 1I. Institute of Physics (IA), RWTH Aachen Univerity, Sommerfeldstraße 14, 52074 Aachen, Germany — 2Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
Semiconductor nanowires are promising candidates for future nanoelectronic devices. While the bottom-up approach for their growth could simplify the device fabrication, their quantitative characterization remains challenging. We use scattering-type scanning near-field optical microscopy (s-SNOM) to investigate the local density of free electrons in Si-doped InAs nanowires grown by selective-area metalorganic vapor phase epitaxy (SA-MOVPE) [1].
In s-SNOM the evanescent electric field at the apex of an illuminated tip is used to probe a sample at a strongly sub-wavelength resolution. This method is highly sensitive to variations in the sample permittivity around Re(ε)≈−2 [2]. The use of tunable mid-infrared lasers therefore allows addressing the plasma frequency of free charge carriers in highly doped nanowires [3]. Here, we demonstrate that the sensitivity of s-SNOM is sufficient to detect a slight unintended variation in the carrier concentration during the growth process. Furthermore, using model calculations, we give an estimate of the local density of free electrons.
[1] S. Wirths et al., J. Appl. Phys. 110, 053709 (2011).
[2] B. Hauer et al., Opt. Express 20, 13173 (2012).
[3] J. Stiegler et al., Nano Lett. 10, 1387 (2010).