Infrared ellipsometry study of the confined electrons in a high-mobility $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ heterostructure

Abstract

With infrared ellipsometry we studied the response of the confined electrons in a $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ heterostructures in which they originate predominantly from oxygen vacancies. From the analysis of a so-called Berreman mode, that develops near the highest longitudinal optical phonon mode of SrTiO${}_3$, we derive the sheet carrier density, $N_s$, the mobility, $\mu$, and also the depth profile of the carrier concentration. Notably, we find that $N_s$ and the shape of the depth profile are similar as in LaAlO${}_3$/SrTiO${}_3$ heterostructures for which the itinerant carriers are believed to arise from a polar discontinuity. The main differences concern the higher mobility and a relatively stronger confinement of the electrons in $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$

12 pages, 2 figures

References in corpus (8)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Metallic and insulating interfaces of amorphous SrTiO3-based oxide heterostructures
• A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3
• Electron-phonon interaction and charge carrier mass enhancement in SrTiO3
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
• Charge density distribution and optical response of the LaAlO3/SrTiO3 interface
• Optical probe of ferroelectric order in bulk and thin film perovskite titanates
• Optically tuned dimensionality crossover in photocarrier-doped SrTiO${}_3$: onset of weak localization

Cited by in corpus (6)

• Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy
• High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces
• Infrared ellipsometry study of the photo-generated charge carriers at the (001) and (110) surfaces of SrTiO${}_3$ crystals and the interface of corresponding LaAlO${}_3$/SrTiO${}_3$ heterostructures
• Infrared study of the quasi-two-dimensional electron system at the interface between SrTiO${}_3$ and crystalline or amorphous LaAlO${}_3$
• Anisotropy of the infrared-active phonon modes in the mono-domain state of tetragonal SrTiO3 (110)
• Two-dimensional electron gas in a metal/amorphous oxide interface with spin orbit interaction