Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti–O Configurations: Evidence from X-ray Photoelectron Spectroscopy

Abstract

A chemical redox reaction can lead to a two-dimensional electron gas at the interface between a TiO-terminated SrTiO (STO) substrate and an amorphous LaAlO capping layer. When replacing the STO substrate with rutile and anatase TiO substrates, considerable differences in the interfacial conduction are observed. On the basis of X-ray photoelectron spectroscopy (XPS) and transport measurements, we conclude that the interfacial conduction comes from redox reactions, and that the differences among the materials systems result mainly from variations in the activation energies for the diffusion of oxygen vacancies at substrate surfaces.

Magnetic Conductive Outer Layer in Oxygen‐Deficient TiO2 Single Crystals

“…As the temperature decreases, the sample annealed at 600 °C for 10 min exhibits a metal‐to‐insulator transition around 65 K. And its resistance becomes quite large that it is well beyond the limits of Hall effect measurement system. Similar strong localization at low temperature has also been observed in the reduced rutile interface, amorphous LaAlO 3 /TiO 2 . Therein, this upturn is ascribed to the formation of small polarons (see Figure S2, Supporting Information).…”

Anatase TiO2-based two-dimensional electron gases generated by low-energy argon-ion irradiation

“…Only a few TiO 2 -based 2DEGs were reported, and all of them were obtained at the oxide TiO 2 interfaces. 18,19 There are no attempts to build up the 2DEG at the TiO 2 surface through ion irradiation. In this work, we fabricated the 2DEGs by irradiating the surface of anatase TiO 2 films on (001) LaAlO 3 (LAO) substrates with Ar þ ions.…”

X‐Ray Writing of Metallic Conductivity and Oxygen Vacancies at Silicon/SrTiO3 Interfaces

“…[25,42] In addition, oxygen vacancies remain the most common dopant in oxides, and together with the non-epitaxial growth of Si that does not require lattice matching substrates, this approach may be applicable across a wide range of oxides, including TiO2-based systems. [43][44] Methods Amorphous silicon thin films with different thicknesses have been prepared on commercial SurfaceNet TiO2-terminated STO(001) substrates by the sequential thermal evaporation at room temperature in UHV (5x10 -10 mbar). After each a-Si coverages were completed, the sample was transferred into the analysis chamber without breaking the UHV and measured at 12 K. The thicknesses were defined by Ti 2p core level peak attenuation induced by the overlayer.…”