LNNano - Brazilian Nanotechnology National Laboratory

Research

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The research areas of the LCS include working with semiconductor nanostructures as well as instrumentation projects. They are carried out in our using the thin film growth equipment, the SPM instruments and the facilities of the CNPEM. We aim to provide state of the art SPM techniques to our users as well as contribute independently to several fields of science. We have a various national and international collaborators providing samples, input or that come to use the LCS. For the latest results, have a look in our publications.


Freestanding Membranes

research In the last years, freestanding membranes were established as a building block for nanotechnology. Investigated structures include stretchable electronics, free-standing solar cells, free-standing Si membranes for high mobility, wrinkled semiconductor membranes as well as rolled-up and folded three-dimensional micro- and nano-objects.
Currently, members of the LCS are involved into different projects using freestanding membranes. We work on the overgrowth of freestanding structures to investigate the influence of compliant substrates to the formation of self-assembled nanostructures (supported by FAPESP and CNPq).
Furthermore, we are working on emerging device structures based on rolled-up membranes. For these projects, we collaborate with the Microfarication laboratory of the LNNano as well as run some small deposition equipment.

Figure: AFM image of a overgrown, wrinkled InGaAs nanomembrane with InAs islands.

Published: Nanotechnolgy 25, 455603 (2014).


Nanoscale characterization of 2D materials

2D materials like graphen or MoS2 have gained a tremendous attention in the last years. Using our strong background in semiconductor nanomembranes and having access to advanced characterization methods of the various national labs, we starting to establish a research line to characterize these materials on the nanometer scale. These involves work in collaboration with the UFMG as well as first test with purchased material inside the local facilities.

We expect that these kinds of studies improve the base understanding and device development using these exiting new materials.

Figure: AFM image (height and phase contrast) of a MoS2 flake. The phase (bottom) illustrates the different materials (substrate and the 2D crystal), whereas we can identify the two layered flake by its height step in the top image.


Instrumentation

To provide state-of-the-art equipment for our users, the LCS is constantly involved in instrumentation development and improvement of the existing facilities.

We attack different instrumentation request by our users implementing new techniques (e.g. working in liquids) on our SPM instruments. Thereby, we try to provide a in depth background of the used technique carrying out detailed instrumentation works. Such works are made available either by internal memorandums or instrumentation papers. Furthermore, we have a strong background in Ultra High Vacuum devices and equipment due to our MBE and STM facilities. Finally, we are involved in SPM setups to be used with Synchrotron light, e.g. the end station of the IR beamline.

Figure: The image shows our self-assembled heater for the MBE system. It can reach temperatures of ca. 1000°C and works with Omicron sample holder plates.