Black Phosphorus Gains On Graphene

Posted: Jul 9 2015, 10:34am CDT | by , in News | Latest Science News


Black Phosphorus Gains on Graphene
Crystals of black arsenic phosphorus -- exchanging phsphorus against arsenic, the band gap can be tuned to as low as 0.15 eV, making the material predestined for long wavelength infrared sensors. Andreas Battenberg / TUM

A new research report pushes black phosphorus as competition to the miracle material graphene.

Summary for the busy Geek

Black phosphorus gains in popularity among the research community hailing it as another material that can be made one atom thin. Black phosphorus is a semiconductor and can be use to make ultra tiny transistors and sensors. Chemists at the Technische Universität München (TUM) have now developed produced a field effect transistor made of black arsenic phosphorus. The material is made by replacing individual phosphorus atoms by arsenic.

Earlier this week another Black phosphorus research made headlines that shows that black phosphorus could replace silicon enabling higher density.

The Details

Graphene, the only one atom thick carbon network, achieved overnight fame with the 2010 Nobel Prize. But now comes competition: Such layers can also be formed by black phosphorous. Chemists at the Technische Universität München (TUM) have now 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.

For many decades silicon has formed the basis of modern electronics. To date silicon technology could provide ever tinier transistors for smaller and smaller devices. But the size of silicon transistors is reaching its physical limit. Also, consumers would like to have flexible devices, devices that can be incorporated into clothing and the likes. However, silicon is hard and brittle. All this has triggered a race for new materials that might one day replace silicon.

Black arsenic phosphorus might be such a material. Like graphene, which consists of a single layer of carbon atoms, it 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 cooperation between the Technical University of Munich and the University of Regensburg on the German side and the University of Southern California (USC) and Yale University in the United States has now, for the first time, produced a field effect transistor made of black arsenic phosphorus. The compounds were synthesized by Marianne Koepf at the laboratory of the research group for Synthesis and Characterization of Innovative Materials at the TUM. The field effect transistors 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. This requires less energy and is cheaper. The gap between valence and conduction bands can be precisely controlled by adjusting the arsenic concentration. "This 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 Synthesis and Characterization of Innovative Materials.

With an arsenic concentration of 83 percent 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 automobiles. 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 research titled "Black Arsenic-Phosphorus: Layered Anisotropic Infrared Semiconductors with Highly Tunable Compositions and Properties" authored by Bilu Liu, Marianne Köpf, Ahmad N. Abbas, Xiaomu Wang, Qiushi Guo, Yichen Jia, Fengnian Xia, Richard Weihrich, Frederik Bachhuber, Florian Pielnhofer, Han Wang, Rohan Dhall, Stephen B. Cronin, Mingyuan Ge, Xin Fang, Tom Nilges, Chongwu Zhou Adv. Mater., 2015 was published in Wiley Online Library Advanced Materials.

Deep Knowledge for Geeks

Black phosphorus is the thermodynamically stable form of phosphorus at room temperature and pressure. It is obtained by heating white phosphorus under high pressures (12,000 atmospheres). In appearance, properties and structure it is very much like graphite, being black and flaky, a conductor of electricity, and having puckered sheets of linked atoms. Phonons, photons, and electrons in layered black phosphorus structures behave in a highly anisotropic manner within the plane of layers, exhibiting strong potential for applications to thin film electronics and infrared optoelectronics. Via Wikipedia.

IBM has just achived another big leap in chip density without Black phosphorus. IBM uses silicon-germanium (SiGe) in the world's first 7nm chip.


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The Author

<a href="/latest_stories/all/all/2" rel="author">Luigi Lugmayr</a>
Luigi Lugmayr () is the founding chief Editor of I4U News and brings over 15 years experience in the technology field to the ever evolving and exciting world of gadgets. He started I4U News back in 2000 and evolved it into vibrant technology magazine.
Luigi can be contacted directly at




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