研究目的
Investigating the deposition of Eu metal on SrTiO3/Si pseudo-substrates with varying SrTiO3 thickness and temperature to understand the oxygen scavenging process and its effects on the formation of epitaxial EuO.
研究成果
The oxygen scavenging process for Eu on STO substrates is temperature and thickness dependent. At 300 °C, Eu forms epitaxial EuO on thick STO layers (>4 nm), while on thinner layers, it disrupts the STO structure and reacts with Si. Below 150 °C, oxygen scavenging is limited, resulting in a thin EuO layer and accumulation of Eu metal. This study provides insights into the growth process and conditions necessary for controlling the formation of EuO/STO heterostructures.
研究不足
The study is limited by the specific conditions of ultrahigh vacuum and the range of STO thicknesses and deposition temperatures explored. The reaction mechanisms at temperatures below 150 °C and the exact nature of the solid-state reaction between Eu, Si, and STO at high temperatures require further investigation.
1：Experimental Design and Method Selection:
The study involves the deposition of Eu metal on SrTiO3/Si pseudo-substrates under ultrahigh vacuum conditions, varying the thickness of the STO layer and the deposition temperature. In situ x-ray photoelectron spectroscopy (XPS) and reflection high-energy electron diffraction (RHEED) are used to monitor the electronic structure and crystallinity of the growing film.
2：Sample Selection and Data Sources:
SrTiO3/Si pseudo-substrates with STO layer thicknesses of 2, 3, 4, 6, and 10 nm are prepared. Eu metal is deposited from an effusion cell at a fixed temperature.
3：List of Experimental Equipment and Materials:
A customized DCA 600 MBE system with a base pressure of 6 × 10?10 Torr, effusion cell for Eu deposition, in situ XPS with monochromated Al Kα radiation, and RHEED with 21 keV electrons.
4：Experimental Procedures and Operational Workflow:
Eu metal is deposited on the STO/Si substrates at two different temperatures (20 °C and 300 °C). The growth process is monitored in situ by RHEED, and the electronic structure is analyzed by XPS after each deposition step.
5：Data Analysis Methods:
The core levels Eu 3d, Eu 4d, Si 2p, Ti 2p, and O 1s are measured as a function of Eu coverage to obtain information about the scavenging process. The valence band (VB) spectra are also analyzed to confirm the formation of stoichiometric EuO.
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