Scalable Al₂O₃–TiO₂ Conductive Oxide Interfaces as Defect Reservoirs for Resistive Switching Devices

Abstract

Resistive switching devices herald a transformative technology for memory and computation, offering considerable advantages in performance and energy efficiency. Here, a simple and scalable material system of conductive oxide interfaces is employed, and their unique properties are leveraged for a new type of resistive switching device. An Al2O3–TiO2‐based valence‐change resistive switching device, where the conductive oxide interface serves both as the bottom electrode and as a reservoir of defects for switching, is demonstrated. The amorphous–polycrystalline Al2O3–TiO2 conductive interface is obtained following the technological path of simplifying the fabrication of the 2D electron gases (2DEGs), making them scalable for practical mass integration. Physical analysis of the device chemistry and microstructure with comprehensive electrical analysis of its switching behavior and performance is combined. The origin of the resistive switching is pinpointed to the conductive oxide interface, which serves both as the bottom electrode and as a reservoir of oxygen vacancies. The latter plays a key role in valence‐change resistive switching devices. The new device, based on scalable and complementary metal–oxide–semiconductor (CMOS)‐technology‐compatible fabrication processes, opens new design spaces toward increased tunability and simplification of the device selection challenge.

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.…”

Gradual conductance modulation by defect reorganization in amorphous oxide memristors

“…A memristor is a resistance-switchable non-volatile device that was first defined by Chua in the last century as the fourth basic electronic component. 1 It has the advantages of energy-efficiency, 2 high speed, 3 simple structures, 4 easy integration, 5 and compatibility with traditional semiconductor manufacturing processes. 6 At the moment when Moore's Law is becoming increasingly shackled, memristors are considered to be the most potential candidates for next-generation non-volatile memory devices.…”

High-performance resistive random access memory using two-dimensional electron gas electrode and its switching mechanism analysis

“…Several applications for this unique conducting layer have been published, for example, as a channel layer in a fieldeffect transistor or the bottom electrode of a conductive bridge random access memory device to enhance uniformity [1,2]. However, among the reported applications, the utilization of the 2DEG as an electrode of oxide-based resistive random access memory (OxRAM) is of particular interest [3][4][5][6][7].…”

“…However, while the oxide electrolyte is stoichiometric, the leakage current decreases but the voltage required to form V o filaments increases. Because the 2DEG formed via the ALD process can be considered as an n-type semiconductor, where V o serves as a donor, this trade-off can be addressed by applying the 2DEG as an electrode of RRAM, where it plays the role of an oxygenscavenging layer for the oxide [4,7,12]. The resulting RRAM with the 2DEG has a low leakage current on account of the stoichiometric oxide electrolyte, and requires only a low voltage to form V o filaments.…”

“…The resulting RRAM with the 2DEG has a low leakage current on account of the stoichiometric oxide electrolyte, and requires only a low voltage to form V o filaments. Although some authors have reported on this application of a 2DEG to RRAM, the existing studies have limitations with regards to high-density memory applications due to the large cell size of the devices used (μm-cm scale) and non-uniform current-voltage (I-V ) characteristics [4,7].…”