Novel Electrical Properties of Nanoscale Thin Films of a Semiconducting Polymer: Quantitative Current-Sensing AFM Analysis
2007; American Chemical Society; Volume: 23; Issue: 17 Linguagem: Inglês
10.1021/la700785h
ISSN1520-5827
AutoresJiyoun Kim, Shinhyo Cho, Seungchel Choi, Sungsik Baek, Dongjin Lee, Ohyun Kim, Su‐Moon Park, Moonhor Ree,
Tópico(s)Analytical Chemistry and Sensors
ResumoThin films (20-150 nm thickness) of poly(o-anthranilic acid) with various doping levels were prepared on silicon substrates with deposited indium tin oxide, and their topography and current-voltage (I-V) characteristics were quantitatively investigated using current-sensing atomic force microscopy with a platinum-coated tip. The films were found to have a surface morphology like that of orange peel, with a periodic modulation and a surface roughness. The films exhibited nonuniform current flows and I-V characteristics that depended on the doping level as well as on the film thickness. Films with a high doping level were found to exhibit Zener diode switching behavior, whereas the films with a very low doping level (or that were dedoped) exhibited no current flow at all, and so are insulators. Interestingly, self-doped films (which are at an intermediate doping level) were found to have a novel electrical bistability, i.e., a switching characteristic like that of Schottky diodes, and increasingly insulating characteristics as the film thickness was increased. The films with thickness < or =62 nm, which exhibited this novel and stable electrical bistability, can potentially be used in the fabrication of high-density, stable, high-performance digital nonvolatile memory devices based only on transistors. The measured current images and I-V characteristics indicate that the electrical switching and bistability of the films are governed by local filament formation and charge traps.
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