Article abstract
Nature Materials 7, 391 - 398 (2008)
Published online: 6 April 2008 | doi:10.1038/nmat2164
Subject Categories: Optical, photonic and optoelectronic materials | Computation, modelling and theory
A chemically driven insulator–metal transition in non-stoichiometric and amorphous gallium oxide
Lakshmi Nagarajan1, Roger A. De Souza1, Dominik Samuelis1, Ilia Valov2, Alexander Börger3, Jürgen Janek2, Klaus-Dieter Becker3, Peter C. Schmidt4 & Manfred Martin1
Abstract
Insulator–metal transitions are well known in transition-metal oxides, but inducing an insulator–metal transition in the oxide of a main group element is a major challenge. Here, we report the observation of an insulator–metal transition, with a conductivity jump of seven orders of magnitude, in highly non-stoichiometric, amorphous gallium oxide of approximate composition GaO1.2 at a temperature around 670 K. We demonstrate through experimental studies and density-functional-theory calculations that the conductivity jump takes place at a critical gallium concentration and is induced by crystallization of stoichiometric Ga2O3 within the metastable oxide matrix—in chemical terms by a disproportionation. This novel mechanism—an insulator–metal transition driven by a heterogeneous solid-state reaction—opens up a new route to achieve metallic behaviour in oxides that are expected to exist only as classic insulators.
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
- Institute of Physical Chemistry, Justus Liebig University, 35392 Giessen, Germany
- Institute of Physical and Theoretical Chemistry, Technical University of Braunschweig, 38106 Braunschweig, Germany
- Institute of Physical Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
Correspondence to: Manfred Martin1 e-mail: martin@rwth-aachen.de
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