Graphene has been considered a hot candidate for a new generation of silicon-free electronics since the discovery of this two-dimensional form of carbon.
However, graphene is not a semiconductor. In the journal Angewandte Chemie, an international team of researchers has now introduced a carbon nitride, a structural analogue of graphene made of carbon and nitrogen that appears to exhibit semiconducting properties.
With a planar, hexagonal, honeycomb structure and freely moving electrons, graphene is, in principle, nothing more than a single-atom layer of graphite. From an electronic point of view, it is a very interesting substance – but it is missing the typical electronic band gap that would make it a semiconductor.
This band gap is the difference in energy between the valence band and the conduction band of the electrons. To be effective, this gap must not be too large, so that it allows electrons to easily move from the valence band to the conduction band when excited.
Various methods have previously been used to provide graphene with such a band gap. An alternative idea is to make a “graphitic carbon nitride”, a material made of carbon and nitrogen, which ought to have properties very similar to graphene.
A team of researchers from the University of Liverpool (UK), the University of Ulm (Germany), the Humboldt University in Berlin (Germany), the Aalto University (Finland), University College London (UK), and the Max Planck Institute of Colloids and Interfaces in Potsdam (Germany) has now been able to make such a material for the first time.
Transmission electron microscopy and scanning force microscopy, as well as X-ray crystallographic examinations proved that the thin crystalline films are a triazine-based, graphitic carbon nitride (TGCN). Triazines are six-membered rings containing three carbon and three nitrogen atoms.
The new material consists of such triazine rings, with additional nitrogen atoms connecting the rings into groups of three to make a two-dimensional layer. The team led by Andrew I. Cooper and Michael J. Bojdys believes that these layers are not fully planar, but are instead slightly wavy.
TGCN thus has a structure similar to that of graphite, however—as hoped—it is a semiconductor. The films produced consisted of between three and several hundred layers of atoms with a direct band gap between 1.6 and 2.0 eV. During the production process, the layers of TGCN are preferentially deposited onto substrates. The crystallization of TGCN on the surface of insulating quartz offers potential for practically relevant applications. This may be a step on the way to the post-silicon era of electronics.
Dr. Michael J. Bojdys initiated this work as a postdoctoral researcher funded by an EPSRC Programme Grant in Liverpool. He is now a junior group leader at the TU Bergakademie Freiberg, working on organic functional materials for energy and storage applications.
Author: Andrew I. Cooper, University of Liverpool (UK), http://www.liv.ac.uk/cooper-group/people/
Title: Triazine-Based, Graphitic Carbon Nitride: a Two-Dimensional Semiconductor
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201402191
Andrew I. Cooper | Angewandte Chemie
New method to identify microscopic failure
18.08.2016 | Beckman Institute for Advanced Science and Technology
Enhanced electron doping on iron superconductors discovered
16.08.2016 | Institute for Basic Science
Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
25.08.2016 | Event News
24.08.2016 | Event News
12.08.2016 | Event News
26.08.2016 | Health and Medicine
26.08.2016 | Earth Sciences
26.08.2016 | Life Sciences