Self-Assembled TaO_X/2H-TaS₂ as a van der Waals Platform of a Multilevel Memristor Circuit Integrated with a β-Ga₂O₃ Transistor

Abstract

Two-dimensional (2D)-layered material tantalum disulfide (2H-TaS 2 ) is known to be a van der Waals conductor at room temperature. Here, 2D-layered TaS 2 has been partially oxidized by utraviolet-ozone (UV-O 3 ) annealing to form a 12nm-thin TaO X on conducting TaS 2 , so that the TaO X /2H-TaS 2 structure might be self-assembled. Utilizing the TaO X /2H-TaS 2 structure as a platform, each device of a β-Ga 2 O 3 channel MOSFET and a TaO X memristor has been successfully fabricated. An insulator structure of Pt/TaO X /2H-TaS 2 shows good a dielectric constant (k ∼ 21) and strength (∼3 MV/cm) of achieved TaO X , which is enough to support a β-Ga 2 O 3 transistor channel. Based on the quality of TaO X and low trap density of the TaO X /β-Ga 2 O 3 interface, which is achieved via another UV-O 3 annealing, excellent device properties such as little hysteresis (<∼0.04 V), band-like transport, and a steep subthreshold swing of ∼85 mV/dec are achieved. With a Cu electrode on top of the TaO X /2H-TaS 2 structure, the TaO X acts as a memristor operating around ∼2 V for nonvolatile bipolar and unipolar mode memories. The functionalities of the TaO X /2H-TaS 2 platform become more distinguished finally when the Cu/TaO X /2H-TaS 2 memristor and β-Ga 2 O 3 MOSFET are integrated to form a resistive memory switching circuit. The circuit nicely demonstrates the multilevel memory functions. KEYWORDS: β-Ga 2 O 3 , vdW, platform, memristor, transistor

Nanoristors: highly uniform, sub-500-millivolt, large-scale, and robust molybdenum disulfide nanograined memristors

“…Memristors are emerging as future storage devices owing to their desirable structure for high-density integration and vertical stacking based on their crossbar array. 1–3 In addition, studies in recent years have reported that memristors have the potential to be used in advanced applications such as neuromorphic systems owing to their characteristics such as multi-state switching, 4,5 low-power consumption, 6,7 and non-volatility. 8,9 Despite the diverse potential of memristors, one of the biggest challenges in implementing practical applications using memristive devices is ensuring uniformity and reliability.…”