New technician of nanoimagen to study the structure and conductivity of the cables

Scientific of the Centre of Cooperative Investigation nanoGUNE and IK4-Cidetec, both in San Sebastián (Guipúzcoa), have presented in Nature Communications the ‘nanoscopía infrared-electronic correlated', a new method of taking of nanoimágenes that allows to understand better the relation between local structure, conductivity and chemical composition of nanocables of oxide of zinc.

For this the team has combined the designated s-SNOM —taking of images and infrared spectroscopy with a space resolution of less than 20 nm to produce ‘maps' of chemical composition and conductivity—, beside the electronic microscope of transmission (TEM), that facilitates structural information with atomic resolution.

“Have developed a manufacturing of special samples that allows to combine these two technicians in an only sample”, explains Andrey Chuvilin, researcher of nanoGUNE. “And, as we showed in our study, the correlation between the images taken with TEM and with s-SNOM will help to obtain a deeper knowledge of the properties of the materials to scale nanométrica”, adds Johannes Stiegler, of the same centre.

To check the possibilities that offers the nanoscopía, the researchers have studied transversal sections of nanohilos of oxide of zinc (ZnO). These components present a big potential to be used in the transport of electrons in different fields, like the solar plates, sensors emisores of light and nanogeneradores piezoelectric. However, up to now they know few appearances on the local conductivity inside these ‘cables'.

Observing the infrared images of s-SNOM the researchers have found a profile of radial conductivity, but his origin and properties explains with the help of a TEM. The regions of little conductivity of the ‘wire' of ZnO show crystalline defects significantes. From the two images can conclude that it gives a reverse correlation between the density of the defects and the concentration of free bearers (conductivity).

Ramón Tena-Zaera, director of the Unit Fotovoltáica of IK4-Cidetec, explains that “this new technician allows, for the first time, obtain all this information on an only sample”. “Our results open new possibilities in the growth and the integration of nanohilos of ZnO”.

Up to now the scientific community had centred in obtaining nanohilos with the lower possible diameter because they considered that had potential elder. By the contrary, the new results suggest that a greater lateral —growth diameter— has more advantages to achieve free materials of defects and of high electronic conductivity.

Although in this study have used for a special sample, “the method of the nanoscopía infrared-electronic correlated has a much more extensive applicability —concludes Rainer Hillenbrand, leader of the Group of Nanoóptica of nanoGUNE and coordinator of the study—and has a big potential to study new materials like the grafeno, topological insulation, materials of change of phase (PCM), or nanoestructuras biological and organic”.

bibliographic Reference:

Stiegler J.M., Tena-Zaera R., Idigoras Or., Chuvilin To. And Hillenbrand R. “Correlative infrared–electron nanoscopy reveals the Local structure–conductivity relationship in zinc oxide nanocables”. Nature Communications 3:1131, 2012. Doi: 10.1038/ncomms2118.