Annealing Behaviours of Open Spaces in Thin Al2O3 Films Deposited on Semiconductors Studied Using Monoenergetic Positron Beams

A. Uedonoa, W. Eggerb, T. Koschineb, C. Hugenschmidtc, M. Dickmannc, S. Ishibashid aDivision of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan bUniversität der Bundeswehr München, Institut für Angewandte Physik und Messtechnik, 85577 Neubiberg, Germany cPhysics Department E21 and Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, 85748 Garching, Germany dResearch Center for Computational Design of Advanced Functional Materials (CD-FMat), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan

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Open spaces in amorphous Al2O3 films fabricated by atomic layer deposition and in AlONx deposited by a reactive sputtering technique were probed by using monoenergetic positron beams. In these films, open spaces with three different sizes were found to coexist. The mean size and the concentration of open spaces were decreased by annealing at 800° in N2 atmosphere, which was associated with rearrangements of the amorphous network in the films and their crystallization. Nitrogen incorporation into Al2O3 suppressed the shrinkage of network structures due to the annealing, which was attributed to the formation of a stable network through the introduction of Al-N bonding. For Al2O3 deposited on GaN, the temperature treatment above 800° led to the introduction of vacancy-type defects in the GaN substrate. This fact suggests that the change in the network structure of Al2O3 enhances chemical instability at the Al2O3/GaN interface and the out-diffusion of atoms from the substrate.

DOI:10.12693/APhysPolA.137.227 PACS numbers: 61.72.-y, 68.55.Ln, 78.70.Bj