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Band structure tuning at (La,Sr)MnO3 / (Ba,Sr)TiO3 interface
Archive ouverte : Communication dans un congrès
Edité par HAL CCSD
International audience. Band structure engineering in silicon-based heterostructures dedicated to microelectronic and energy harvesting applications has been common material scientist playground for decades. Careful design of the energy level variation at hetero-interfaces is used e.g. to collect electron while preventing electron-hole recombination in PV heterostructures, control electron injection with Schottky barriers (SB), promote quantum well... Although band structure engineering in Si or GaAs based heterostructures is a very mature field, it is a relatively new territory for oxide electronic where emerging new device concepts based on perovskite-derived heterostructures makes it very desirable. In all perovskite-based heterostructures, the structural continuity at ABO3 hetero-interfaces gives extra degrees of freedom to tune electronic and structural properties. Rumpling, polar discontinuity, interfacial B-site cation environment asymmetry, BO6 octahedral rotations are all potential levers to alter the band structure and promote electronic properties like e.g. interface polarization [1] or enhanced SB height [2,3].One way to play with these degrees of freedom is to modulate the interface chemical composition by introducing an Interface Control Layer (ICL), as it has been proposed decades ago for Si and GaAs based heterostructures. [3] To accelerate the exploration of ICL perovskite materials, we implemented an interface combinatorial pulsed laser deposition (ICPLD) set-up. [4] We report here on epitaxial La0.7Sr0.3MnO3/ ICL (3uc) /SrTiO3 (0-9uc) junctions with ICL = La1-xSrxMnO3 and Ba1-ySryTiO3. XPS/UPS spectroscopies were used to probe core levels, work function (WF) and band bending versus ICL composition and STO thickness. Modulation of WF leading to a transition from Schottky to ohmic contact with the polar discontinuity will be discussed together with interface atomic structure characterized by HR-STEM.
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