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Updated: Sep 18, 2025
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Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown
Published on: February 14, 2014
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Photoelectron Spectra of Small Gallium and Aluminum Radicals
Emil Karaev1, Dorothee Schaffner1, Marius Gerlach1
1Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany.
The Journal of Physical Chemistry. A
|June 25, 2025
Summary
We determined the ionization energies of aluminum methyl (AlCH3), gallium methyl (GaCH3), and gallium hydroxide (GaOH) using advanced spectroscopy. These findings are vital for optimizing metal-organic vapor phase epitaxy (MOVPE) for advanced semiconductor films.
Area of Science:
- Physical Chemistry
- Materials Science
- Spectroscopy
Background:
- Metal-organic vapor phase epitaxy (MOVPE) is crucial for synthesizing gallium nitride (GaN) and gallium aluminum nitride (GaAlN) thin films.
- Understanding the properties of precursor molecules is essential for controlling MOVPE processes.
Purpose of the Study:
- To experimentally determine the ionization energies and vibrational structures of AlCH3, GaCH3, and GaOH.
- To provide critical data for optimizing MOVPE precursor design and reaction mechanisms.
Main Methods:
- Pyrolysis of trimethylaluminum and trimethylgallium to generate reactive species.
- Characterization using vibrationally resolved threshold photoelectron spectroscopy.
- Utilizing double imaging photoelectron photoion coincidence (DIPPC) spectroscopy at a VUV beamline.
- Franck-Condon simulations based on computed geometries for vibrational assignment.
Main Results:
- Reported ionization energies: AlCH3 (7.89 ± 0.04 eV), GaCH3 (7.90 ± 0.02 eV), and GaOH (9.68 ± 0.02 eV).
- Obtained vibrationally resolved threshold photoelectron spectra for these molecules.
- Successfully assigned vibrational modes through Franck-Condon simulations.
Conclusions:
- The determined ionization energies and spectral data offer fundamental insights into the electronic structure of these key MOVPE intermediates.
- This research provides essential data for the rational design and improved control of GaN and GaAlN thin film deposition.
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