Issue 24, 2022

Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation

Abstract

An Al2O3/ZnO heterojunction was grown on a Si single crystal substrate by subsequent thermal and plasma-assisted atomic layer deposition (ALD) in situ. The band offsets of the heterointerface were then studied by consecutive removal of the layers by argon sputtering, followed by in situ X-ray photoelectron spectroscopy. The valence band maximum and conduction band minimum of Al2O3 are found to be 1.1 eV below and 2.3 eV above those of ZnO, resulting in a type-I staggered heterojunction. An apparent reduction of ZnO to elemental Zn in the interface region was detected in the Zn 2p core level and Zn L3MM Auger spectra. This suggests an interface formation different from previous models. The reduction of ZnO to Zn in the interface region accompanied by the creation of oxygen vacancies in ZnO results in an upward band bending at the interface. Therefore, this study suggests that interfacial properties such as the band bending as well as the valence and conduction band offsets should be in situ controllable to a certain extent by careful selection of the process parameters.

Graphical abstract: Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation

Supplementary files

Article information

Article type
Paper
Submitted
25 Nov. 2021
Accepted
20 Maijs 2022
First published
20 Maijs 2022

Dalton Trans., 2022,51, 9291-9301

Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation

C. Janowitz, A. Mahmoodinezhad, M. Kot, C. Morales, F. Naumann, P. Plate, M. H. Zoellner, F. Bärwolf, D. Stolarek, C. Wenger, K. Henkel and J. I. Flege, Dalton Trans., 2022, 51, 9291 DOI: 10.1039/D1DT04008A

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