lin sun | Northwestern University (original) (raw)
Address: Evanston, United States
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Strongly correlated oxides are full of fascinating phenomena owing to their interacting lattice,... more Strongly correlated oxides are full of fascinating phenomena owing to their
interacting lattice, charge, spin and orbital degrees of freedom.[1–5] Bandgap, a
critical parameter for an oxide insulator, is well determined by those degrees of
freedom and in turn directly affects electronic, magnetic and optical properties of
the material. Typically, tunability of the bandgap in an oxide insulator can be
achieved through chemical doping,[6] which is important for electronic and photonic
device applications. Here we report large bandgap enhancement in SrTiO3 (STO)
thin films, which can be up to 20% greater than the bulk value, depending on the
deposition temperature. There is no significant change in density and cationic ratio
of the oxide so the effect is attributed to Sr/Ti antisite defects, an attribution
supported by density functional theory calculations. It was found that the bandgap
enhancement significantly changes the electronic and magnetic phases in the
oxygen-vacancy-induced two-dimensional electron gas at the interface between
amorphous LaAlO3 (LAO) and STO. This opens an attractive path to tailor
electronic, magnetic and optical properties of STO-based oxide interface systems
under intensive focus in the oxide electronics community. Meanwhile, our study
provides key insight into the origin of the fundamental issue that STO thin films are
difficult to convert into metals by oxygen vacancy doping
We report that in unannealed LAO/STO heterostructures the critical thickness for the appearance o... more We report that in unannealed LAO/STO heterostructures the critical thickness for the appearance of the two-dimensional electron gas can be less than 4 unit cell (uc), the interface is conducting even for STO substrates with mixed terminations and the low-temperature resistance upturn in LAO/STO heterostructures with thick LAO layers strongly depends on laser fluence. Our experimental results provide fundamental insights into the different roles played by oxygen vacancies and polarization catastrophe in the two-dimensional electron gas in crystalline LAO/STO heterostructures.
Strongly correlated oxides are full of fascinating phenomena owing to their interacting lattice,... more Strongly correlated oxides are full of fascinating phenomena owing to their
interacting lattice, charge, spin and orbital degrees of freedom.[1–5] Bandgap, a
critical parameter for an oxide insulator, is well determined by those degrees of
freedom and in turn directly affects electronic, magnetic and optical properties of
the material. Typically, tunability of the bandgap in an oxide insulator can be
achieved through chemical doping,[6] which is important for electronic and photonic
device applications. Here we report large bandgap enhancement in SrTiO3 (STO)
thin films, which can be up to 20% greater than the bulk value, depending on the
deposition temperature. There is no significant change in density and cationic ratio
of the oxide so the effect is attributed to Sr/Ti antisite defects, an attribution
supported by density functional theory calculations. It was found that the bandgap
enhancement significantly changes the electronic and magnetic phases in the
oxygen-vacancy-induced two-dimensional electron gas at the interface between
amorphous LaAlO3 (LAO) and STO. This opens an attractive path to tailor
electronic, magnetic and optical properties of STO-based oxide interface systems
under intensive focus in the oxide electronics community. Meanwhile, our study
provides key insight into the origin of the fundamental issue that STO thin films are
difficult to convert into metals by oxygen vacancy doping
We report that in unannealed LAO/STO heterostructures the critical thickness for the appearance o... more We report that in unannealed LAO/STO heterostructures the critical thickness for the appearance of the two-dimensional electron gas can be less than 4 unit cell (uc), the interface is conducting even for STO substrates with mixed terminations and the low-temperature resistance upturn in LAO/STO heterostructures with thick LAO layers strongly depends on laser fluence. Our experimental results provide fundamental insights into the different roles played by oxygen vacancies and polarization catastrophe in the two-dimensional electron gas in crystalline LAO/STO heterostructures.