Elucidate the electrical switching phenomenon for hetero-LB film

研究了Cd-花生酸盐和C15 TCNQ组成的异质LB膜的电学性质、X射线衍射分析和表面形貌。结果如下。(1)通过沉积比和X射线衍射测试发现，Cd-花生酸盐LB膜为Y型结构。另一方面，C15 TCNQ LB膜从沉积率澄清为Y型或Z型结构，这取决于基底的性质（亲水性或疏水性）。(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电阻值相当。(4)发现了异质LB膜的电开关现象。当电压施加在膜的正向或横向时，膜的电阻从高阻态（OFF态）向低阻态（ON态）转变，Cd-花生酸盐LB膜和不含Cd离子的C15 TCNQ LB膜没有出现电开关现象，而含Cd离子的C15 TCNQ LB膜出现了电开关现象。结果表明，异质LB膜的电开关现象是由Cd和C15 TCNQ的电荷转移引起的。

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.