CeNS Colloquium

Prof. Wilfred G. van der Wiel
University of Twente

A smart combination of inorganic and organic materials and the integration of top-down and bottom-up (self-assembly) techniques in nanoelectronic structures may on the one hand allow for the study of key problems in solid-state physics, and on the other hand lead to functional devices with potentially technological relevance. In this presentation I would like to illustrate this approach with some of our recent experimental studies.

We have applied patterned molecular monolayers of dopant-containing organic molecules to selectively dope silicon with carriers. Very high doping concentrations can be obtained and the method should be suitable to dope also 3D semiconductor devices. We present a novel, facile molecular fabrication method for inserting isolated, localized magnetic moments in a metal film with tunable density [2]. Electrical transport measurements demonstrate that the magnetic impurity concentration can be systematically varied up to ~800 ppm concentration without any sign undesired clustering.

In a different geometry, we have measured the magnetoresistance in 1D molecular wires. An ultra-high (~10³%), room-temperature magnetoresistance is observed at very moderate magnetic fields of only a few mT [3]. We explain these results in terms of the dramatic effect of spin blockade in 1D electron transport.

References

1. W.P. Voorthuijzen et al., Langmuir 26 (17), 14210-14215 (2010); W.P. Voorthuijzen et al., Advanced Materials 23, 1346 (2011).
2. T. Gang et al., Nature Nanotechnology 7, 232 (2012).
3. R.N. Mahato et al., manuscript under review.