Electrical rectification by monolayers of three molecules

Rectification, i.e. asymmetrical electrical conduction by a Langmuir-Blodgett monolayer of dicyano{4-[1-cyano-2-(1-hexadecylquinolin-1-ium-4-yl)vinyl]phenyl} methanide ( 1 ), occurs between both Al and Au electrodes: this rectification arises from the asymmetry of the molecule, and the interplay between the zwitterionic ground state D⁺-π-A⁻ and the less dissociated first electronic excited state D⁰-π-A⁰. Two more monolayer rectifiers have been found: 1-butyl-2,6-bis{2-[4-(dibutylamino)phenyl] vinyl}pyridin-1-ium iodide ( 2 ) is an interionic rectifier with back charge transfer between the iodide ion and the pyridinium ring. 1a-[4-(dimethylamino)phenyl]-1aH-1a-aza-1(2)a-homo(C₆₀-I_h)[5,6]fullerene ( 3 ) is a moderate rectifier, with a rectification ratio of 2.     

Alkyl Monolayer Passivated Metal–Semiconductor Diodes: 2: Comparison with Native Silicon Oxide

To understand the electrical properties at passivated metal–semiconductor interfaces, two types of mercury–insulator–silicon (n‐type) junctions, Hg|C₁₀H₂₁? Si and Hg|SiO₂? Si, were fabricated and their current–voltage and capacitance–voltage characteristics compared. Both of them exhibited near‐ideal rectifying characteristics with an excellent saturation current at reverse bias, which is in contrast to the previously reported ohmic behavior of an unmodified mercury–silicon junction. The experimental results also indicated that the n‐decyl monolayer passivated junction possesses a higher effective barrier height, a lower ideality factor (that is, closer to unity), and better reproducibility than that of native silicon oxide. In addition, the dopant density and build‐in potential, extracted from capacitance–voltage measurements of these passivated mercury–silicon junctions, revealed that alkyl monolayer derivatization does not alter the intrinsic properties of the silicon substrate. The calculated surface state density at the alkyl monolayer|silicon interface is lower than that of the silicon oxide|silicon interface. The present study increases the possibility of using advanced organic materials as ultrathin insulator layers for miniaturized, silicon‐based microelectronic devices.     

自组装成膜技术制备TiO2薄膜的XPS研究

采用自组装成膜技术制备里TiO2薄膜,应用X射线光电子能谱研究自组装膜及其氧化膜和淀积的TiO2薄膜，结果表明，硅烷偶联剂成功地组装在玻璃基片上，足够长时间的氧化对使端基（-SH）完全氧化为磺酸基，淀积在基片上的TiO2膜牢固性好，平均膜厚在10nm．淀积膜中的钛可能有几种不同的氧化态，不同的酸度影响TiO2的淀积效果