Scientists develop molecular memory device using monolayer

Prof. Lee Hyo-young's team at SungKyunKwan University raises possibility for development of next-generation memory device.

A Korean research team has developed a molecular memory device using a monolayer. According to the Ministry of Education, Science and Technology on October 8, a research team led by Prof. Lee Hyo-young of the department of chemistry at SungKyunKwan University successfully produced a molecular monolayer nonvolatile memory device using a monolayer of organic metal measuring 3-4 nanometers in length, which retains an oxidation and reduction reaction status. Successfully generates nonvolatile molecular memory using 'unforgettable monolayer'

The study was conducted jointly by the department of chemistry and the Center for Smart Molecular Memory at SungKyunKwan University with the support of the "Creative Research Initiatives research fund", a program for assisting pioneering researchers. The fund is supported by the Ministry of Education, Science and Technology (Minister Ahn Byung-man) and the Korea Research Foundation (Chairman Park Chan-mo).

The study was published on October 1 in the online edition of Angewandte Chemie, a world-renowned chemistry journal. The research paper introduced the technology as "unforgettable monolayer", since it showed the possibility for developing a molecular nonvolatile memory using a monolayer.

(photo A) diagram of a molecular memory device using a monolayer organic metallic compound

Molecular electronic devices are considered part of a promising field for the future that will replace the inorganic semiconductor technology of the present. Since such devices allow for ultrahigh density integration per unit space, studies using copolymers have been conducted extensively. However, questions still linger over limitations in integration due to "cross-talk", a shortcoming of copolymer. Efficiency of device significantly enhanced through current-voltage-inducing material and alkyl chain Using a monolayer allows for integration, but the process could reduce the yield of the device due to an "electric short" caused by penetration of metallic particles when producing electrodes. Hence, research has been conducted to address this problem as well. Up until now, when producing upper electrodes with a molecular memory device using a monolayer, carbon
nanotubes and metal nanowire were used, but those materials had limitations in commercialization.

Prof. Lee's team discovered a new method to solve the problems that arise in the course of producing the upper metallic electrode. The team prevented the electric short phenomenon from occurring by placing a conductive organic material between the monolayer organic metallic compound and the upper metallic electrodes. It also removed the penetration of conductive materials and significantly increased the efficiency of the device by increasing alkyl chains on the monolayer organic metallic compound.

a and b show the switch-on mode using an monolayer organic metallic compound, while c shows the stability of reading in two currents with -1.0 volt in reading voltage

(Photo) a and b show the switch-on mode using an monolayer organic metallic compound, while c shows the stability of reading in two currents with -1.0 volt in reading voltage

Additionally, in order to produce the device, the scientists inserted alkyl molecules with different lengths on both ends of the monolayer organic metallic molecules, which retain oxidation and reduction characteristics. By so doing, they increased the molecular density and prevented the penetration of conductive copolymer, thus increasing the yield of the device. Furthermore, they found that as the length of alkyl increases, the device' yield also increases, while its non-volatility grows in tandem.

Professor Lee hyo-young, chief investigator

(Photo) Prof. Lee Hyo-young, chief investigator

Prof. Lee stressed that, "In order for Korea, which dominates the global memory chip market, to maintain its lead in the next-generation memory chip market, research must focus on the development of diverse types of next-generation nonvolatile memory devices", adding, "The study has identified for the first time the possibility for developing a molecular memory device using a monolayer, which allows for integration." Prof. Lee, who led the study, acquired his doctorate degree from the University of Mississippi. A professor of chemistry at SungKyunKwan University, Lee currently heads the university's Center for Smart Molecular Memory.

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Lim Dong-wook, Kim Chung-han

duim at kofac.or.kr



[October 14, 2009]

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Source - ScienceTimes