Black arsenic phosphorus

Print edition : August 07, 2015

Black arsenic phosphorus, a reflection electron microscope image. Photo: TUM, Munich

FOR many decades, silicon has formed the basis of modern electronics. But the size of silicon transistors is reaching its physical limit and silicon is hard and brittle, whereas a flexible material would be more suitable for new applications of semi- conductors. This has triggered a search for new materials. Graphene—the one-atom-thick sheet of carbon with desirable electrical properties, strength and flexibility—is fast emerging as the promising new material that might one day replace silicon. Chemists at the Technical University of Munich (TUM) have developed black arsenic phosphorus, a new material in which individual phosphorus atoms are replaced by arsenic, which could become a competing alternative to graphene. Like graphene, it forms extremely thin layers. Unlike graphene, it behaves like a semiconductor.

Cooperation between the TUM and the University of Regensburg in Germany and the University of Southern California and Yale University in the U.S. has now, for the first time, produced a field effect transistor made of black arsenic phosphorus. The new technology developed at the 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 precisely tuned 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,” said Tom Nilges of TUM.

With an arsenic concentration of 83 per cent the material exhibits an extremely small band gap of only 0.15 electronvolt, making it ideal for sensors for detecting far infrared radiation. Light Detection and Ranging sensors operate in this wavelength range, for example. They are used, among other things, in the measurement of dust particles and trace gases in environmental monitoring.

A letter from the Editor


Dear reader,

The COVID-19-induced lockdown and the absolute necessity for human beings to maintain a physical distance from one another in order to contain the pandemic has changed our lives in unimaginable ways. The print medium all over the world is no exception.

As the distribution of printed copies is unlikely to resume any time soon, Frontline will come to you only through the digital platform until the return of normality. The resources needed to keep up the good work that Frontline has been doing for the past 35 years and more are immense. It is a long journey indeed. Readers who have been part of this journey are our source of strength.

Subscribing to the online edition, I am confident, will make it mutually beneficial.

Sincerely,

R. Vijaya Sankar

Editor, Frontline

Support Quality Journalism
This article is closed for comments.
Please Email the Editor