A group of the Institute of Photonics of the Vienna University of Technology has demonstrated the ability of graphene to convert light into electrical signal in an extremely rapid. This allows to consider applications for example in the transfer of data between computers. Expectations graphene Graphene, an allotrope of carbon where the atoms are arranged in a single layer of cells in the manner of a hive (see illustration below), drew the attention of scientists and industrialists since 2004, when its first isolation. Although relatively abundant in nature, especially since it forms the basis of graphite [1], reaching isolate a single layer with a thickness of an atom is a technological challenge. However, it is a promising material in several respects: its tensile strength is 200 times higher than steel for a lower mass, and its electrical resistivity is lower than that of silver, which is the substance with the lowest resistivity at room temperature. Its various properties are logically the subject of active research – the 2010 Nobel Prize in Physics has been awarded as a result of progress in research on graphene.

A reaction time of 2.1 picoseconds

The researchers from the Advanced Technological University of Vienna is in this context. Already last year, a group of the Faculty of Electrical Engineering and Information Technology showed that graphene was very quickly able to convert light into electrical signal using the photoelectric effect. The reaction time was then could not be measured because of its exceptional brevity, is now done: making use of technical tips, because conventional methods do not measure time as short, researchers have shown the reaction time of a detector they designed in graphene is 2.1 picoseconds (10-12 s worth a picosecond, or trillionth of a second). Using two ultrashort laser pulses in quick succession which varies the separation time and then measuring the current created, it is possible to determine the maximum frequency of use of the detector. It has been found that such graphene-based sensors allow a frequency of 262 GHz, allowing a data transfer rate theoretical maximum of over 30 gigabytes per second range of wavelengths – the current rise commercial networks best at a rate of 1.2 gigabytes per second. Such performances can be obtained due to the short lifetime of charge carriers in graphene. The electrons dislodged from their location by the incident light found a place in just a few picoseconds, and the detector is again ready to receive another pulse of light. These results confirm the interest of graphene as a material of optoelectronic components e-at high speed. If similar performance was obtained with systems not using graphene, one must note that they are so severely limited by the fields of wavelengths used, while the graphene absorbs light over a wide range from the infrared to visible. - [1] pencil leads are made ​​of graphite for example. Graphite consists of a superposition of layers of graphene.

Source:

- Press the Technical University of Vienna (in German) http://www.tuwien.ac.at/aktuelles/news_detail/article/7070 /
- Kurier article dated June 27, 2011 (in German) http: / / kurier.at/techno/3917862.php