Issue 17, 2009
From the journal:

Physical Chemistry Chemical Physics

An in situXAS investigation of the kinetics of the ammonolysis of Ga2O3 and the oxidation of GaN

J. Brendt,*a   D. Samuelis,†a   T. E. Weirichb  and  M. Martin*a  

* Corresponding authors

a Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
E-mail: brendt@pc.rwth-aachen.de; martin@rwth-aachen.de

b Central Facility for Electron Microscopy, RWTH Aachen University, Ahornstraße 55, 52074 Aachen, Germany

Abstract

The ammonolysis of β-Ga2O3 to α-GaN and the oxidation of α-GaN to β-Ga2O3 have been studied by means of in situX-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In situ X-ray absorption measurements on polycrystalline powder particles on the gallium K-edge during both reactions give detailed information about the reaction kinetics. We were able to extract this kinetics by fitting linear combinations of β-Ga2O3 and α-GaN spectra only. The kinetics of the ammonolysis can be described well by an extended Johnson–Mehl–Avrami–Kolmogorow model, while the oxidation kinetics can be modelled by a shrinking core model. Investigations by means of TEM and SEM support the assumptions in both models. Our experimental results and the models are discussed in terms of the reaction energetics and the reaction mechanisms.

Graphical abstract: An in situXAS investigation of the kinetics of the ammonolysis of Ga2O3 and the oxidation of GaN

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Article information

DOI
https://doi.org/10.1039/B901819K
Article type
Paper
Submitted
28 Jan 2009
Accepted
24 Feb 2009
First published
19 Mar 2009

Phys. Chem. Chem. Phys., 2009,11, 3127-3137

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An in situXAS investigation of the kinetics of the ammonolysis of Ga2O3 and the oxidation of GaN

J. Brendt, D. Samuelis, T. E. Weirich and M. Martin, Phys. Chem. Chem. Phys., 2009, 11, 3127 DOI: 10.1039/B901819K

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