Influence of SrTiO 3 capping layer on the charge transport at the interfaces of SrTiO 3 /LaAlO3/SrTiO 3 (100) heterostructure
Journal
Physical Review Materials
Journal Volume
2
Journal Issue
11
Pages
114009-1 - 114009-9
Date Issued
2018
Author(s)
Abstract
The experimental realization of quasi-two-dimensional hole gas at the complex oxide interface has long been a grand challenge that may open up new possibilities for oxide-based electronics. SrTiO3 (STO)-capped LaAlO3 (LAO)/SrTiO3 (100) is a potential candidate that has been recently demonstrated to show possible electron-hole bilayer conducting channels near the interfaces of the heterostructure. In this work we present a systematic investigation on the structural and magnetotransport properties of STO-capped and uncapped LAO/STO (100) samples that were grown by an oxide molecular beam epitaxy system. The STO/LAO/STO (100) samples exhibit metallic interfaces down to T = 2 K even with a LAO thickness of merely 3 unit cells (3-uc). On the contrary for uncapped LAO(5-uc)/STO (100) samples the conducting interface becomes insulating at lower temperatures due to the surface adsorbate on top of the LAO as revealed from x-ray photoelectron spectroscopy measurements. The magnetotransport data at different back-gate voltages for STO-capped and uncapped LAO/STO (100) samples were analyzed and compared to each other using the two-band model. The presence of two types of charge carriers with opposite signs is uniquely found for STO/LAO/STO (100) samples which is in big contrast to the uncapped LAO/STO (100) samples with only electron-type carriers. Our results support the coexistence of electron-type and hole-type carriers in the STO/LAO/STO (100) heterostructure where their sheet densities and mobilities can be tuned significantly by electrical gating effect and the layer thickness of the heterostructure.
SDGs
Publisher
American Physical Society
Type
journal article