Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material
Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material.
The new technique could lead to the simple creation and manufacture of superconductors or high-efficiency solar cells and light sensors, said leader of the research, Professor Andrei Rode, from The Australian National University (ANU).
"We've created two entirely new crystal arrangements, or phases, in silicon and seen indications of potentially four more," said Professor Rode, a laser physicist at the ANU Research School of Physics and Engineering (RSPE).
"Theory predicts these materials could have very interesting electronic properties, such as an altered band gap, and possibly superconductivity if properly doped"
By focusing lasers onto silicon buried under a clear layer of silicon dioxide, the group have perfected a way to reliably blast tiny cavities in the solid silicon. This creates extremely high pressure around the explosion site and forms the new phases.
The phases have complex structures, which took the team of physicists from ANU and University College London a year to understand.
Using a combination of electron diffraction patterns and structure predictions, the team discovered the new materials have crystal structures that repeat every 12, 16 or 32 atoms respectively, said Professor Jim Williams, from the Electronic Material Engineering group at RSPE.
"The micro-explosions change silicon's simplicity to much more complex structures, which opens up possibility for unusual and unexpected properties," he said.
These complex phases are often unstable, but the small size of the structures means the materials cool very quickly and solidify before they can decay, said Professor Eugene Gamaly, also from the ANU Research School of Physics and Engineering. The new crystal structures have survived for more than a year now.
"These new discoveries are not an accident, they are guided by a deep understanding of how lasers interact with matter," he said.
Conventional methods for creating materials with high pressure use tiny diamond anvils to poke or squeeze materials. However, the ultra-short laser micro-explosion creates pressures many times higher than the strength of diamond crystal can produce.
The team's new method promises a much cheaper and industrially-friendly method for large scale manufacturing of these exotic materials, says Dr Jodie Bradby, also from ANU Research School of Physics and Engineering.
"We reliably create thousands of micron-size modified zones in normal silicon within a second," she said.
"The semiconductor industry is a multi-billion dollar operation - even a small change in the position of a few silicon atoms has the potential to have a major impact."
Andrei Rode | EurekAlert!
New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State
Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
26.09.2017 | Life Sciences
26.09.2017 | Physics and Astronomy
26.09.2017 | Information Technology