Beyond graphene: monolayer arsenene observed for the first time at MAX IV

Beyond graphene: monolayer arsenene observed for the first time at MAX IV

An article recently published in 2D Materials shows the first experimental evidence of the successful formation of arsenene, an analogue of graphene with noteworthy semiconducting properties. This material shows a great potential for the development of new nanoelectronics. Crucial sample preparation and electron spectroscopy experiments were performed at the Bloch beamline at MAX IV.

The discovery of graphene, the single-layer carbon honeycomb material worth the Nobel Prize in Physics in 2010, surely has had a revolutionary impact on research. It triggered a whole new field of study within two-dimensional (2D) materials. However, its application in developing new 2D electronics has been hindered by its lack on an intrinsic band gap. Researchers therefore started to turn their attention to other elements in the periodic table and set their eyes on group V, to which arsenic belongs.

“The aim of the study was to show that arsenene can be formed. Our article is the first to report this”, says Roger Uhrberg, professor at Linköping University and spokesperson for the Bloch beamline at MAX IV. Arsenene, a single-layer buckled honeycomb structure of arsenic, had been previously predicted by various theoretical studies, but this is the first experimental observation that verifies its existence.

The development of 2D electronics gained momentum after the characterization of graphene. However, researchers’ hopes for potential applications of this revolutionary material in electronics were soon challenged by graphene’s lack of an intrinsic band gap. “The attention has now turned to other graphene-like 2D materials of which the group V atoms are of special interest since theory predicts substantial band gaps, in some cases exceeding 2 eV”, explains Weimin Wang, beamline scientist at the Bloch beamline and co-author of the study.

Band gap, also called energy gap, is a fundamental property of semiconductors that determines a material’s electronic properties. Single-layer structures predicted for elements from group V (phosphorus, arsenic, antimony, and bismuth) show a promising band gap value. “Semiconductors are essential materials for building electronic components. 2D honeycomb structures of group V atoms are predicted to be semiconducting with band gaps suitable for various electronic applications. Our paper verifies that arsenene can be formed and that it has a sizeable band gap in contrast to graphene”, clarifies Roger Uhrberg.

A view of the Bloch beamline at MAX IV. The Bloch beamline consists of two branchlines, and is dedicated to high resolution photoelectron spectroscopy, encompassing angle-resolved (ARPES), spin resolved (spin-ARPES) and core-level spectroscopy.

Professor Uhrberg goes on explaining the experiments that were performed at Bloch. The arsenene layer was grown in-situ on a silver Ag(111) surface using one of the preparation chambers at the Bloch end station. The researchers then performed experiments of low-energy electron diffraction (LEED) and angle resolved photoelectron spectroscopy (ARPES). “The deflection mode of the electron analyser at Bloch has been very useful to obtain the ARPES data set needed in order to verify the electron band structure of the 2D arsenene layer”. Uhrberg knows the beamline very well. In addition to being Bloch’s spokesperson, he was in fact deeply involved in the design and development of the beamline and end station.

The investigation and characterization of different single-layer materials sparked by graphene is an important step that will help us understand the future applications of these revolutionary materials. “Our report on arsenene formation opens up for extensive explorations of this promising material for next generation electronic and optoelectronic devices”, concludes Weiming Wang. “We believe that the present research topic is of significant interest to future nano-electronics.”

Read the article here:

Shah, W. Wang, H.M. Sohail, and R.I.G. Uhrberg,
Experimental evidence of monolayer arsenene: an exotic 2D semiconducting material
2D Mater. 7, 025013 (2020)

Related publication by the same authors with data from MAX-Lab:

Shah, H.M. Sohail, R.I.G. Uhrberg, and W. Wang,
Two-Dimensional Binary Honeycomb Layer Formed by Ag and Te on Ag(111)
J. Phys. Chem. Lett. 11, 1609 (2020)

Read more article on 2D materials research at MAX IV:

First Users at Balder Beamline Seek to Illuminate MXenes

Promising steps towards large scale production of graphene nanoribbons for electronics

Graphene takes a step towards renewable fuel

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