Elucidate the electrical switching phenomenon for hetero-LB film

研究了由C15TCNQ和C15TCNQ组成的杂化LB膜的电学性质、X射线分析和表面形貌。主要研究结果如下：(1)沉积比和X射线衍射仪测试结果表明，Cd-花生四酸盐LB膜为Y型结构。另一方面，根据衬底的性质(亲水性或疏水性)，C15TCNQ LB膜的沉积比例被明确为Y型或Z型结构。(2)AFM观察到LB膜的表面形貌非常光滑。(3)用四探针法测量了异质LB膜的电学性质，其电阻值几乎与绝缘体的一样高。(4)我们发现了异质LB膜的电开关现象。当电压施加到薄膜的正向或横向时，薄膜的电阻从高阻态(OFF态)切换到低阻态(ON态)，不含Cd离子的C15TCNQ LB膜和C15TCNQ LB膜没有表现出电开关现象，而含有Cd离子的C15TCNQ LB膜则出现了这种现象。结果表明，Cd和C15TCNQ的电荷转移引起了异质LB膜的电开关现象。

The electric properties, X-ray analysis and surface morphology of hetero LB films consisting of Cd-Arachidate and C15TCNQ were investigated. The results are as follows.(1) It was found from deposition ratio and X-ray diffraction measurement that Cd-Arachidate LB films were Y type-structure. On the other hand, C15TCNQ LB films were clarified from deposition ratio to be Y-type or Z-type structure depending on the nature (hydrophilic or hydrophobic) of the substrate.(2) The surface morphology of the LB films observed by AFM was quite smooth.(3) The electric properties of hetero LB films were measured by a four probe method, and the value of electrical resistance was almost as high as that of insulator.(4) We found the electrical switching phenomenon for the hetero LB films. The electrical resistance switches from higher resistance state (OFF state) to lower resistance state (ON state), when the voltage is applied to the normal or lateral direction of the film.The Cd-Arachidate LB films and C15TCNQ LB films without Cd ion did not show the electrical switching phenomenon, however, the C15TCNQ LB films with Cd ion showed the phenomenon. It is concluded that the electrical switching phenomenon of hetero LB films is caused by the charge -transfer of Cd and C15TCNQ.