Kim Jiyoun, Cho Shinhyo, Choi Seungchel, Baek Sungsik, Lee Dongjin, Kim Ohyun, Park Su-Moon, Ree Moonhor
Department of Chemistry, Center for Integrated Molecular Systems, Pohang University of Science and Technology (Postech), Pohang 790-784, Republic of Korea.
Langmuir. 2007 Aug 14;23(17):9024-30. doi: 10.1021/la700785h. Epub 2007 Jul 13.
Thin 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.
在沉积有铟锡氧化物的硅衬底上制备了具有不同掺杂水平的聚（邻氨基苯甲酸）薄膜（厚度为20 - 150纳米），并使用涂有铂的探针通过电流传感原子力显微镜对其形貌和电流 - 电压（I - V）特性进行了定量研究。发现这些薄膜具有类似橘皮的表面形态，具有周期性调制和表面粗糙度。薄膜表现出不均匀的电流流动以及取决于掺杂水平和薄膜厚度的I - V特性。发现高掺杂水平的薄膜表现出齐纳二极管开关行为，而极低掺杂水平（或去掺杂）的薄膜根本没有电流流动，因此是绝缘体。有趣的是，发现自掺杂薄膜（处于中间掺杂水平）具有一种新颖的电双稳性，即具有类似于肖特基二极管的开关特性，并且随着薄膜厚度增加绝缘特性增强。厚度≤62纳米且表现出这种新颖且稳定的电双稳性的薄膜有可能仅基于晶体管用于制造高密度、稳定、高性能的数字非易失性存储器件。测量的电流图像和I - V特性表明，薄膜的电开关和双稳性受局部细丝形成和电荷陷阱的控制。
