Intensity dependent deflection spectroscopy for the characterization of absorption mechanisms in semiconductors

authored by: Walter Dickmann, Tom Götze, Mark Bieler, Stefanie Kroker
Abstract: We report on a simple method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. Therefore, we perform spatially resolved and intensity dependent deflection spectroscopy to measure the local optical absorption. To separate the absorption mechanisms, we take advantage of different intensity scaling of these mechanisms and extract the material parameters by fitting intensity dependent absorption to a physical model. This model takes into account relevant optical absorption processes like linear absorption from defect states, two-photon absorption, and the Franz-Keldysh effect. The method is exemplarily carried out for GaAs, Si, and CdTe. The literature values of the two-photon absorption coefficient are reproduced and the strength of the Franz-Keldysh effect in CdTe is determined for the first time as C FK = [8.7, ., 16.9] × 10 13 m - 1 s - 1 / 2.
External Organisation(s): Technische Universität Braunschweig
National Metrology Institute of Germany (PTB)
Type: Article
Journal: Journal of applied physics
Volume: 128
ISSN: 0021-8979
Publication date: 28.07.2020
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Physics and Astronomy(all)
Electronic version(s): https://doi.org/10.1063/5.0012702 (Access: Open)

BibTeX

@article{d4ad1f4dc3fd4cb19e920dd72a7fa9d3,
title = "Intensity dependent deflection spectroscopy for the characterization of absorption mechanisms in semiconductors",
abstract = "We report on a simple method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. Therefore, we perform spatially resolved and intensity dependent deflection spectroscopy to measure the local optical absorption. To separate the absorption mechanisms, we take advantage of different intensity scaling of these mechanisms and extract the material parameters by fitting intensity dependent absorption to a physical model. This model takes into account relevant optical absorption processes like linear absorption from defect states, two-photon absorption, and the Franz-Keldysh effect. The method is exemplarily carried out for GaAs, Si, and CdTe. The literature values of the two-photon absorption coefficient are reproduced and the strength of the Franz-Keldysh effect in CdTe is determined for the first time as C FK = [8.7, ., 16.9] × 10 13 m - 1 s - 1 / 2. ",
author = "Walter Dickmann and Tom G{\"o}tze and Mark Bieler and Stefanie Kroker",
note = "Funding information: The authors gratefully acknowledge support from the Braunschweig International Graduate School of Metrology B-IGSM and the DFG Research Training Group GrK1952/1 “Metrology for Complex Nanosystems.” S.K. also acknowledges partial support from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) under Germany{\textquoteright}s Excellence Strategy EXC-2123 QuantumFrontiers—390837967.",
year = "2020",
month = jul,
day = "28",
doi = "10.1063/5.0012702",
language = "English",
volume = "128",
journal = "Journal of applied physics",
issn = "0021-8979",
publisher = "American Institute of Physics",
number = "4",
}