Ternary Flash Memory with a Carbazole-Based Conjugated Copolymer: WS₂ Composites as Active Layers.

Area of Science:

• Materials Science
• Nanotechnology
• Electrical Engineering

Background:

• Nonvolatile memory devices require advanced substrate materials for optimal performance.
• Organic/inorganic nanomaterials are actively researched for memory device active layers due to versatile fabrication methods like spin coating.
• Tungsten disulfide nanoparticles (WS₂ NPs) offer large surface area and conductivity, acting as effective charge trap centers.

Purpose of the Study:

• To synthesize a novel polymer, Poly[2,7-9-(9-heptadecanyl)-9H-carbazole-co-benzo[4,5]imidazole[2,1-α]isoindol-11-one] (PIIO).
• To fabricate and investigate the memory characteristics of ITO/PIIO/Al and ITO/PIIO:WS₂ NP/Al devices.
• To optimize the WS₂ nanoparticle mass fraction for enhanced memory performance.

Main Methods:

• Suzuki coupling reaction for PIIO synthesis.
• Spin coating and vacuum evaporation for device fabrication.
• Characterization of tristate switching behavior and performance metrics (current ratio, threshold voltage, stability).

Main Results:

• All fabricated devices exhibited tristate switching behavior.
• The optimal memory performance was achieved with a 6 wt% WS₂ NP composite.
• The optimized device showed a high OFF/ON1/ON2 current ratio (1:1.11 × 10¹, 2.03 × 10⁴) and stable operation for 12,000 s and 3500 read cycles.

Conclusions:

• The PIIO and WS₂ NP composite demonstrates excellent potential for next-generation nonvolatile memory applications.
• The integration of WS₂ NPs into the polymer matrix significantly enhances charge transfer and memory characteristics.
• The developed memory devices exhibit robust performance, including high endurance and retention, making them suitable for practical applications.