Researchers in China, [J. Appl. Cryst. (2014). 47, 527-531] have found a convenient way to selectively prepare germanium sulfide nanostructures, including nanosheets and nanowires, that are more active than their bulk counterparts and could open the way to lower cost and safer optoelectronics, solar energy conversion and faster computer circuitry.
Germanium monosulfide, GeS, is emerging as one of the most important "IV–VI" semiconductor materials with potential in opto-electronics applications for telecommunications and computing, and as an absorber of light for use in solar energy conversion.
One important property is its much lower toxicity and environmental impact when compared to other semiconductors made with cadmium, lead and mercury.
It is less costly than other materials made with rare and noble metal elements. Indeed, glassy GeS has been used in lasers, fibre optic devices and infrared lenses as well as rewritable optical discs and non-volatile memory devices for several years. It is also used extensively as a solid electrolyte in conductive bridging random access memory (RAM) devices.
The repertoire of this material might be extended much further with the extra control that its use as nanostructured systems might allow. Liang Shi and Yumei Dai of the University of Science and Technology of China, in Hefei, point out that research in this area has lagged behind that with other IV-VI semiconductors.
They hope to change that and have focused on how nanosheets and nanowires of GeS might be readily formed. They have used X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy to investigate the structure, morphology, composition and optical absorption properties of their samples.
The team used simple "wet" chemistry to synthesis their products using germanium dichloride-dioxane complex, thiourea and oleylamine (OLA) as starting materials. The ingredients were mixed in a sealed reaction flask, blasted with ultrasound to exclude air and then stirred and heated.
The team was able to make nanosheets of GeS this way if the process was carried out for several hours at 593 Kelvin. At higher temperature, 613 Kelvin, they found that the sheets wind up into nanowires. Indeed, the precise heating time and temperature allowed them to control the structure of the final product. The team suggests that the rolling up of the nanosheets into nanowires is driven by the surface tension between the sheet and the OLA molecules during the heating.
Having proven the structural integrity of their GeS nanowires and nanosheets, the team built several test devices - a photoresponsive unit - which they used to evaluate the optical and electronic properties of the products. The team says that they have demonstrated "outstanding photoresponsive behaviour". This "indicates the potential use of as-synthesized GeS nanosheets and nanowires in solar energy conversion systems, such as the fabrication of photovoltaic devices".
For more information please contact
Dr Jonathan Agbenyega
Business Development Manager, IUCr
00 +44 (0) 1244 342878
About the IUCr
The IUCr is a scientific union adhering to the International Council for Science (ICSU). Its objectives are to promote international cooperation in crystallography and to contribute to all aspects of crystallography, to promote international publication of crystallographic research, to facilitate standardization of methods, units, nomenclatures and symbols, and to form a focus for the relations of crystallography to other sciences.
The IUCr fulfils these objectives by publishing in print and electronically primary scientific journals through Crystallography Journals Online, the series of reference volumes International Tables for Crystallography, distributing the quarterly IUCr Newsletter, maintaining the online World Directory/Database of Crystallographers, awarding the Ewald Prize and organising the triennial Congress and General Assembly.
Dr. Jonathan Agbenyega | EurekAlert!
First direct observation and measurement of ultra-fast moving vortices in superconductors
20.07.2017 | The Hebrew University of Jerusalem
Manipulating Electron Spins Without Loss of Information
19.07.2017 | Universität Basel
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
19.07.2017 | Event News
12.07.2017 | Event News
12.07.2017 | Event News
20.07.2017 | Information Technology
20.07.2017 | Materials Sciences
20.07.2017 | Physics and Astronomy