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Interface engineering for a stable chemical structure of oxidized-black phosphorus via self-reduction in AlOx atomic layer deposition

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Abstract

We evaluated the change in the chemical structure between dielectrics (AlOx and HfOx) grown by atomic layer deposition (ALD) and oxidized black phosphorus (BP), as a function of air exposure time. Chemical and structural analyses of the oxidized phosphorus species (PxOy) were performed using atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, first-principles density functional theory calculations, and the electrical characteristics of field-effect transistors (FETs). Based on the combined experiments and theoretical investigations, we clearly show that oxidized phosphorus species (PxOy, until exposed for 24 h) are significantly decreased (self-reduction) during the ALD of AlOx. In particular, the field effect characteristics of a FET device based on Al2O3/AlOx/oxidized BP improved significantly with enhanced electrical properties, a mobility of ∼253 cm2 V−1 s−1 and an on–off ratio of ∼105, compared to those of HfO2/HfOx/oxidized BP with a mobility of ∼97 cm2 V−1 s−1 and an on–off ratio of ∼103–104. These distinct differences result from a significantly decreased interface trap density (Dit ∼ 1011 cm−2 eV−1) and subthreshold gate swing (SS ∼ 270 mV dec−1) in the BP device caused by the formation of stable energy states at the AlOx/oxidized BP interface, even with BP oxidized by air exposure.

Graphical abstract: Interface engineering for a stable chemical structure of oxidized-black phosphorus via self-reduction in AlOx atomic layer deposition

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Publication details

The article was received on 17 Aug 2018, accepted on 08 Nov 2018 and first published on 09 Nov 2018


Article type: Paper
DOI: 10.1039/C8NR06652C
Citation: Nanoscale, 2018, Advance Article
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    Interface engineering for a stable chemical structure of oxidized-black phosphorus via self-reduction in AlOx atomic layer deposition

    D. Kim, J. Chae, S. Hong, H. Park, K. Jeong, H. Park, S. Kwon, K. Chung and M. Cho, Nanoscale, 2018, Advance Article , DOI: 10.1039/C8NR06652C

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