Ferroelectricity

Characteristic of the Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ film interface with the Si (100) surface

A. T. Kozakov^a, A. V. Nikol'skii^a, V. M. Mukhortov^b, Yu. I. Golovko^b, A. A. Skriabin^a, D. V. Stryukov<sup>b

a</sup> Research Institute of Physics, Southern Federal University, Rostov-on-Don, Russia
^b Southern Research Center of the Russian Academy of Sciences, Rostov-on-Don, Russia

Abstract: Using X-ray photoelectron spectroscopy, the chemical bonds at the interface between the single-crystal surface of a silicon substrate ($p$- and $n$-type) and the Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ (BST) film of Si(100)/Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ heterostructures, which were created by sputtering ceramic Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ targets in a high-frequency $\gamma$-discharge at elevated oxygen pressure ($\sim$ 1 Torr) using the “Plasma 50 SE” unit. Chemical bonds at the interface between the single-crystal surface of a silicon substrate ($p$- and $n$-type) and the Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ (BST) film of Si(100)/Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ heterostructures have been studied using X-ray photoelectron spectroscopy. Heterostructures were created by sputtering a Ba$_{0.8}$Sr$_{0.2}$TiO$_3$ ceramic target in a high-frequency $\gamma$-discharge at a sufficiently high oxygen pressure ($\sim$ 1 Torr) on the “Plasma 50 SE” installation of two orientations of crystallites in the films: [001] and [011]. The bulk fraction of BST crystallites with [001] orientation is 96% for the $n$-type Si substrate and 97% for the $p$-type Si substrate. The bulk fraction of BST crystallites with [011] orientation is 4% for the $n$-type Si substrate and 3% for the $p$-type Si substrate. X-ray electron studies have shown that 46% of the silicon atoms at the interface are bound to oxygen, belonging to the BST structure; 18% of silicon atoms belong to the SiO$_2$ layer. In addition, at the interface there are titanium and strontium atoms chemically bonded to the silicon atoms and oxygen atoms of the BST structure. The Si/BST interface is sharp and at a thickness of $\sim$ 6 $\mathring{\mathrm{A}}$ is already fully formed.

Keywords: X-ray photoelectron spectroscopy, chemical bonds, interface, surface, silicon substrate, crystallites.

Received: 02.10.2023
Revised: 02.10.2023
Accepted: 10.10.2023

DOI: 10.61011/FTT.2023.11.56553.217

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