The first single-molecule diode schematic。
Associate professor of applied physics at Columbia University Rasa & middot; Venkataraman directed research team has developed a new technology, successfully created the first single-molecule diode performance of all to 50 times higher than the previous design, is expected in nano-devices into practical use in the field. Papers published in the May 25 "Nature & middot; Nanotechnology" magazine.
Single-molecule devices are miniaturized ultimate electronic equipment. Yali Ye & middot; Ivor Lyme and Mark & middot; Reiter in 1974 suggested that a single molecule can be used as a rectifier, a unidirectional current conductors. Since then, scientists have been demonstrated monomolecular connected to the metal electrode (monomolecular junction) can be used as a variety of components, including resistors, switches, transistors, and diodes.
The diode acts as a power valve, which requires an asymmetric structure, so that the current in both directions in different environments. According to physicist organizational network reported that in order to develop single-molecule diode, the researchers designed a simple molecule with an asymmetric structure.
& ldquo; although this asymmetric molecules indeed show some class diode characteristics, but they are not effective. & rdquo; first author, doctoral student Brian & middot; Kapo Zi explained that, & ldquo; good design diode should only allows current flow in one direction & mdash; & mdash; turning direction, and the current strength to be big. Asymmetric molecular design often appear on (ON) and off (OFF) both directions weak current flowing phenomenon, and on-current and off current ratio (rectification ratio) is usually low. And ideally, it should be very high rectification ratio. & rdquo;
In order to overcome problems related to asymmetric molecular design, Venkataraman's team will focus on the creation of an asymmetric molecular structure environment. Their method is quite simple & mdash; & mdash; active molecules surrounded by an ionic solution and contacted with metal electrodes of different molecular sizes.
As a result, single-molecule diode rectifier than they get reached 250, higher than the previous design 50 times. Venkataraman noted diode on-current can exceed 0.1 microamperes, for single molecules, this current has been great. In addition, it is easy to implement new technologies that can be applied to all types of nano-devices, including those devices with graphene electrodes fabricated.
& ldquo; chemistry and physics concepts can be employed to design a molecular circuit, and it has a certain degree of functionality, it is very amazing. & rdquo; Venkataraman said, & ldquo; because the scale is so small that quantum mechanical effects is definitely an important aspect of this device. Therefore, it is possible to create an invisible but the performance was consistent with the expected thing, this is a real success.”
The research team is currently working to understand the physical basis behind this achievement, and attempting to use new molecular system, further improve the rectification ratio.
