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EELS Characterization of Electronic Structure in Group III - Nitrides Compared With Synchrotron Ellipsometry Results

Published online by Cambridge University Press:  02 July 2020

G. Brockt  and
H. Lakner
G. Brockt
Affiliation:
Gerhard-Mercator-Universität Duisburg, Werkstoffe der Elektrotechnik, D-47048, Duisburg, Germany
H. Lakner
Affiliation:
Fraunhofer Institut für Mikroelektronische Schaltungen und Systeme, D-01109, Dresden, Germany
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Extract

EELS in the low loss region of the spectra (< 50eV) provides information on excitations of outer shell electrons and thus the electronic structure of a specimen material which determines its optical properties. In this work dedicated EELS methods for the experimental acquisition and analysis of spectra are described which give improved information about the electronic structure near the bandgap region at a spatial resolution in the range of nanometers. For this purpose we made use of a cold field emission STEM equipped with a dedicated EELS system. This device provides a subnanometer electron probe and offers an energy resolution of 0.35 eV. Application of suitable deconvolution routines for removal of the zero loss peak extracts information on the closest bandgap region while Kramers-Kronig transformation deduces the dielectric properties from the measured energy loss function. These methods have been applied to characterize the optical properties of wide-bandgap materials for the case of group Ill-nitride compounds which are currently the most promising material for applications on optoelectronic devices working in the blue and ultraviolet spectral range.

Type
A. Howie Symposium: Celebration of Pioneering Electron Microscopy
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 692 - 693
Copyright
Copyright © Microscopy Society of America

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