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Proceedings Paper

Infrared Fourier Transform Spectroscopy On Local Vibrational Modes In GaAs
Author(s): B. Dischler; H. Seelewind; W. Jantz; K. Lohnert
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Paper Abstract

Fourier transform infrared (FTIR) spectroscopy has been used to measure local vibrational mode (LVM) absorption from impurities in GaAs. Carbon on an arsenic site (CΑs) is a typical residual shallow acceptor in undoped semi-insulating GaAs and the exact determination of the carbon concentration by LVM spectroscopy is of technical importance. The calibration factor by which the integrated LVM absorption is converted into carbon concentration has been found to depend on sample temperature and on instrument resolution [1-3]. For a 0.3 cm thick undoped GaAs sample with 2x1016 cm-3 carbon we measured the LVM band at temperatures between 5 and 300 K with a resolution of 0.1 cm-1 (Fig.1). At low temperatures the CΑs LVM band splits into five individual lines [4] due to different isotopes among the four Ga ligands (60.4% 69Ga, 39.6% 71Ga). We have plotted the temperature dependence of the center frequency (Fig 2a), of the width of the individual lines (Fig 2b) and of the integrated absorption area (Fig 2c). Remarkable is the similarity of the frequency variation with the lattice expansion [5] in Fig. 2a and the 30% decrease in oscillator strength above 150 K in Fig 2c.

Paper Details

Date Published: 1 December 1989
PDF: 2 pages
Proc. SPIE 1145, 7th Intl Conf on Fourier Transform Spectroscopy, (1 December 1989); doi: 10.1117/12.969560
Show Author Affiliations
B. Dischler, Fraunhofer-Institut fur Angewandte Festkorperphysik (Germany)
H. Seelewind, Fraunhofer-Institut Angewandte Festkorperphysik (Germany)
W. Jantz, Fraunhofer-Institut fur Angewandte Festkorperphysik (Germany)
K. Lohnert, Wacker Chemitronic (Germany)

Published in SPIE Proceedings Vol. 1145:
7th Intl Conf on Fourier Transform Spectroscopy
David G. Cameron, Editor(s)

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