Nonvolatile Resistance Switching on Two-Dimensional Electron Gas

Abstract

Two-dimensional electron gas (2DEG) at the complex oxide interfaces have brought about considerable interest for the application of the next-generation multifunctional oxide electronics due to the exotic properties that do not exist in the bulk. In this study, we report the integration of 2DEG into the nonvolatile resistance switching cell as a bottom electrode, where the metal-insulator transition of 2DEG by an external field serves to significantly reduce the OFF-state leakage current while enhancing the on/off ratio. Using the Pt/Ta2O5-y/Ta2O5-x/SrTiO3 heterostructure as a model system, we demonstrate the nonvolatile resistance switching memory cell with a large on/off ratio (>10(6)) and a low leakage current at the OFF state (∼10(-13) A). Beyond exploring nonvolatile memory, our work also provides an excellent framework for exploring the fundamental understanding of novel physics in which electronic and ionic processes are coupled in the complex heterostructures.

Harnessing Conductive Oxide Interfaces for Resistive Random-Access Memories

“…Several VCM RRAM devices have been recently reported, leveraging such 2DEG electrodes. These include Pt/ LaAlO 3 /SrTiO 3 [26], indium tin oxide (ITO)/LaAlO 3 /SrTiO 3 [28], Pt/Ta 2 O 5-y /Ta 2 O 5-x /SrTiO 3 [27], and Pt/Al 2 O 3 /SrTiO 3 [24].…”

“…Joung et al [27] reported amorphous TaO x /single crystal SrTiO 3 based VCM. Ta 2 O 5-y (TO2)/Ta 2 O 5-x (TO1) bilayer of TaO x was deposited using PLD at 200 °C under 70-100 mTorr oxygen (TO2) and at 700 °C under 0.5 mTorr oxygen (TO1).…”

“…These oxide interfaces provided a fertile ground for the discovery and manipulation of extraordinary physics, such as superconductivity [2][3][4][5], magnetism [6,7], magnetoelectric coupling [8,9], Rashba spinorbit coupling [10], persistent photoconductivity [11,12], and integer/fractional quantum Hall effect [13,14]. Over the last decade, leveraging these phenomena towards various devices, such as transistors [15][16][17][18][19], diodes [20], gas sensors [21], spintronic devices [22,23], and memory devices [24][25][26][27][28][29], has drawn considerable attention. 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.…”

“…Among their various device prospects, recently, 2DEGs were utilized for resistive random-access memories (RRAMs) [24][25][26][27][28]. RRAM devices [34][35][36] are highly attractive for the nextgeneration memories [37,38] and new computing paradigms [39][40][41][42][43][44][45][46].…”

Improved Switching Uniformity of SCLC-RRAM Using the Vertically Formed Nanoscale 2DEG Electrode and Control of Oxygen Vacancy Distribution

“…Seok et al reported that trimethylaluminum (TMA), an Al precursor, creates V o and electrons by reducing the TiO 2 layer, resulting in the formation of 2DEG . This laterally conducting layer formed at the Al 2 O 3 /TiO 2 interface can be interpreted as an n-type semiconductor, where V o serves as a donor, and several researchers have proposed methods to harness this 2DEG as a V o reservoir for RRAM. − Thus, a more compact, scaled S-RRAM can be constructed by establishing a vertical 2DEG and employing it as an electrode and controlling the V o concentration within the RRAM layer via thermal migration from the 2DEG through a minimized active switching region.…”