A variety of mechanisms are reported to play critical roles in contributing to the high carrier/electron mobility in oxide/SrTiO3(STO) heterostructures. By using La0.95Sr0.05TiO3(LSTO) epitaxially grown on different single crystal substrates (such as STO, GdScO3, LaAlO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and CeO2buffered STO) as the model systems, the formation of a conducting substrate surface layer (CSSL) on STO substrate is shown at relatively low growth temperature and high oxygen pressure (725 °C, 5 × 10–4 Torr), which contributes to the enhanced conductivity of the LSTO/STO heterostructures. Different from the conventional oxygen vacancy model, this work reveals that the formation of the CSSL occurs when growing an oxide layer (LSTO in this case) on STO, while neither annealing nor the growth of an Au layer alone at the exact same growth condition generates the CSSL in STO. It demonstrates that the oxide layer actively pulls oxygen from STO substrate at given growth conditions, leading to the formation of the CSSL. The observations emphasize the oxygen transfer across film/substrate interface during the synthesis of oxide heterostructures playing a critical role in functional properties.
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Magnetic and ferroelectric oxide thin films have long been studied for their applications in electronics, optics, and sensors. The properties of these oxide thin films are highly dependent on the film growth quality and conditions. To maximize the film quality, epitaxial oxide thin films are frequently grown on single‐crystal oxide substrates such as strontium titanate (SrTiO3) and lanthanum aluminate (LaAlO3) to satisfy lattice matching and minimize defect formation. However, these single‐crystal oxide substrates cannot readily be used in practical applications due to their high cost, limited availability, and small wafer sizes. One leading solution to this challenge is film transfer. In this demonstration, a material from a new class of multiferroic oxides is selected, namely bismuth‐based layered oxides, for the transfer. A water‐soluble sacrificial layer of Sr3Al2O6is inserted between the oxide substrate and the film, enabling the release of the film from the original substrate onto a polymer support layer. The films are transferred onto new substrates of silicon and lithium niobate (LiNbO3) and the polymer layer is removed. These substrates allow for the future design of electronic and optical devices as well as sensors using this new group of multiferroic layered oxide films.
more » « less- NSF-PAR ID:
- 10528439
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Small Science
- Edition / Version:
- 1
- ISSN:
- 2688-4046
- Format(s):
- Medium: X Size: 2MB Other: PDF-A
- Size(s):
- 2MB
- Sponsoring Org:
- National Science Foundation
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