Performance Comparison of Different Organic Molecular Floating-Gate Memories

In this paper, nanosegmented floating-gate memories consisting of a uniform set of identical organic dye molecules were fabricated and evaluated for potential use as programmable charge storage and charge retention elements in a future flash-memory technology. Viability of molecular thin films to serve as an energetically uniform set of ~1 nm in size charge-retaining sites is tested on a series of molecular materials, the best performing of which are thermally evaporated thin films of 3,4,9,10- perylenetetracarboxylic bis-benzimidazole. The initial results show device durability over 10⁵ program/erase cycles, with hysteresis window of up to 3.3 V, corresponding to charge-storage density as high as 5 × 10¹² cm^-2. Data shows that charge retention is improved for molecular films with lower carrier mobility, which for the first time experimentally confirms in a coherent material set that inhibiting charge transport by nanosegmented floating-gate structures benefits the memory retention.