Molecular electronics

Speaker:      Jan van Ruitenbeek (Head of the Casimir Research Group and Professor of Experimental Physics, Leiden)

Subject:       Molecular Electronics

Location:    Lecture room TNW, TU Delft

Date:            Thursday, January, 13:45-14:45

Author: Jasper Veerman 

In the past 30 years, the sizes of electronic components have been reduced in size. From a few micrometer in size, more recent transistors have sizes in the order of nanometers.  This development creates interest in the future of these components: will it be possible to generate single molecules, properly functioning as diodes and transistors? Jan van Ruitenbeek spoke about a number of developments in the field of molecular electronics.

Currently, organic material is being studied for application in electrical components. Despite the high energy-gap often encountered in organic molecules, organic light emitting diodes (OLEDs)  allow for production of flexible displays. The above-mentioned energy-gap can also be used to generate organic conducting materials, like RF-ID chips for theft protection.

On a smaller scale, mechanically controlled break junctions provide a relatively simple means to experiment with single molecules as electrical components. In Figure 1 below, it can be seen that a wire, fixed to a plate, can be put under enough stress to break.

Figure 1
Figure 1: Mechanically controlled break junctions

The two tips – ends of the broken wire – are still very close. They can be brought so close, that only a single molecule can fit in between. If the black container is then filled with a solution, one of the molecules in the solution will fill the gap. The properties , f.e. conductance, of this single molecule can now be measured. This has been done numerous times, allowing for evaluation of interesting molecules to be implemented in future, single molecule electronics.

The professor also touched upon a last interesting experiment he is involved in. Looking at the scale researchers are starting to operate in, it is desired to build structures with the precision of a single atom. For this purpose, a low temperature scanning tunneling microscope (STM) was built. The tip of this microscope, only one atom in size, was used to drag individual gold atoms along a golden surface. The atoms could be placed anywhere with the help of a Wii-inspired controller, showing the promise of true sub-nanoscale engineering.

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