Therefore, forming such 2DEGs requires epitaxial oxide thin film deposition at high temperatures. Oxide 2DEGs were first reported in epitaxial oxide interfaces, where a complex oxide such as LaAlO 3 is grown, typically by pulsed laser deposition (PLD), on a single-crystal oxide substrate, typically SrTiO 3 ( Figure 1A).
We note that for the sake of convenience and simplicity, we very broadly use the term 2DEGs as a general name for conductive oxide interfaces, covering 2D, quasi-2D systems, and conducting interfaces where the dimensionality is not well-defined. In addition to the exotic phenomena listed above, the emergence of a high sheet density of electrons (typically 10 12∼10 15 cm −2) between two insulators is already attractive for some devices, such as in the role of channels or back electrodes. Over the last decade, leveraging these phenomena towards various devices, such as transistors, diodes, gas sensors, spintronic devices, and memory devices, has drawn considerable attention. These oxide interfaces provided a fertile ground for the discovery and manipulation of extraordinary physics, such as superconductivity, magnetism, magnetoelectric coupling, Rashba spin-orbit coupling, persistent photoconductivity, and integer/fractional quantum Hall effect. Two-dimensional electron gases (2DEGs) can be formed at some oxides interfaces. We conclude by laying out some of the opportunities presented by 2DEGs based RRAM, including increased tunability and design flexibility, which could, in turn, provide advantages for multi-level capabilities.
#SPACECHEM RANDOM OXIDES SERIES#
We consider the immediate challenges to revolve around scaling from one device to large arrays, where further progress with series resistance reduction and fabrication techniques needs to be made. We critically describe and compare recent RRAM devices based on these systems and highlight the possible advantages and potential of 2DEGs systems for RRAM applications. We briefly review the basics of oxide 2DEGs, emphasizing scalability and maturity and describing a recent trend of progression from epitaxial oxide interfaces (such as LaAlO 3/SrTiO 3) to simple and highly scalable amorphous-polycrystalline systems (e.g., Al 2O 3/TiO 2). Recently several works have demonstrated the application of 2DEGs for resistive random-access memories (RRAMs). These properties can be exploited in various novel electronic devices such as transistors, gas sensors, and spintronic devices. Two-dimensional electron gases (2DEGs) can be formed at some oxide interfaces, providing a fertile ground for creating extraordinary physical properties.
Yang Li*, Shahar Kvatinsky and Lior Kornblum*
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