Tropes

www.electronicsweekly.com 2015 03929.txt.txt

#Black arsenic phosphorus could replace silicon Layered semiconducting black arsenic phosphorus could be an alternative to silicon, say researchers at the Technical University of Munich (TUM). TUM chemists have developed a semiconducting material in which individual phosphorus atoms are replaced by arsenic. In a collaborative international effort, American colleagues have built the first field-effect transistors from the new material. Black arsenic forms extremely thin layers. The array of possible applications ranges from transistors and sensors to mechanically flexible semiconductor devices. Unlike graphene, whose electronic properties are similar to those of metals, black arsenic phosphorus behaves like a semiconductor. A co-operation between the TUM, the University of Regensburg, the University of Southern California (USC) and Yale has produced a field effect transistors (fet) made of black arsenic phosphorus. The compounds were synthesised by Marianne Koepf at the laboratory of the research group for Synthesis and Characterization of Innovative Materials (SCIM at the TUM. The fet were built and characterized by a group headed by professor Zhou and Dr Liu at the Department of Electrical engineering at USC. The new technology developed at TUM allows the synthesis of black arsenic phosphorus without high pressure, which requires less energy and is cheaper. The gap between valence and conduction bands can be tuned precisely by adjusting the arsenic concentration. his allows us to produce materials with previously unattainable electronic and optical properties in an energy window that was hitherto inaccessible, says professor Tom Nilges, head of the research group for SCIM. With an arsenic concentration of 83%the material exhibits an extremely small band gap of only 0. 15 electron volts making it predestined for sensors which can detect long wavelength infrared radiation. Lidar (light detection and ranging) sensors operate in this wavelength range, for example. They are used, among other things, as distance sensors in cars. Another application is the measurement of dust particles and trace gases in environmental monitoring. A further interesting aspect of these new, two-dimensional semiconductors is their anisotropic electronic and optical behavior. The material exhibits different characteristics along the x-and y-axes in the same plane. To produce graphene-like films the material can be peeled off in ultra thin layers. The thinnest films obtained so far are only two atomic layers thick. The work was supported by the Office of Naval Research (ONR the Air force Office of Scientific research (AFOSR), the Center of Excellence for Nanotechnologies (CEGN) of King Abdul-Aziz City for Science and Technology (KACST), the German Research Council (DFG) and the TUM Graduate school S

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