Yunzhong Chen and Nini Pryds
Department for Energy Conversion and Storage, Technical University of Denmark, DK-4000 Roskilde, Denmark
Complex oxide heterostructures provides new opportunities to explore nanoelectronic as well as nanoionic devices [1]. When two oxides intimately contact each other, charge redistribution or mass transfer of ions may occur. Herein we show our activities on high mobility 2DEGs at complex oxide interfaces based on STO in addition to creation of superlattices of ionic conductors. Firstly, we will illustrate interfacial redox reaction induced metallic conductivity along the interface of SrTiO3-based heterostructures with various oxide overlayers of amorphous LaAlO3, SrTiO3 (STO) and yttria-stabilized zirconia (YSZ) films [2]. Recently, we create a new type of 2DEG at the heterointerface between SrTiO3 and a spinel gamma-Al2O3 epitaxial film with compatible oxygen ions sublattices [3]. Electron mobilities more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces are obtained. Particularly, electron Hall mobilities as large as 1.4x10E5 cm2V-1s-1 and ns as high as 3.7x10E14 cm-2 at 2 K is obtained. These findings can pave the way for studies of mesoscopic physics with complex oxides and design of high-mobility all-oxide electronic devices. Secondly, we will present our recent results on the strained epitaxial doped ceria thin films which are deposited on diverse substrates to clarify the effect of strain on chemical stability and electrical properties. Particularly, diverse level of strain in doped ceria epitaxial thin films were controlled by varying the thickness of designed buffer layers [4]. The induced strain is found to enhance the in-plane ionic conductivity in doped ceria epitaxial thin films. Finally, we will show that by controlling the growth of the heteroepitaxial thin films is possible to obtain fluorite electrolyte films with superior properties.
Reference:
1. J. Mannhart and D. G. Schlom, Science 327, 1607-1611 (2010).
2. Y. Z. Chen et al. Metallic and insulating interfaces of amorphous SrTiO3-based oxide heterostructures. Nano. Lett. 11, 3774-3778 (2011).
3. Y. Z. Chen et al. Nat. Commun. 4:1371, doi: 10.1038/ncomms2394 (2013).
4. M. Kant et al. App. Phys. Let., 100, 033105 (2012).