Atomic-level deposition to benefit PV cells, LED lighting
A team of scientists at Tyndall National Institute, Ireland, has claimed to have produced the first atom-by-atom simulation of nanoscale film growth by atomic layer deposition (ALD). According to them, the discovery could bring forth a different ALD processing of materials for solar cells and LED lighting.
The virtual insight into atomic-level ALD offers large-scale opportunity for monitoring ultra-thin films used in the semiconductor industry because ALD plays a key role in the manufacture of chips with ever thinner layers for the next generation of electronic devices. Growth simulations could help to improve the ALD process, but until now, were not accurate enough over experimental timescales.
While quantum mechanical simulations give an accurate atom-by-atom picture of individual ALD reactions at the tiniest scales, this is still far removed from what can be measured in the lab, until now.
The Tyndall group led by Simon Elliott has for the first time combined the accuracy from the quantum mechanical level with the statistics needed to follow how thousands of atoms react millions of times a second, building up layers of material, as in the lab.
Mahdi Shirazi, who will be awarded a PhD for this work, explained: "It was crucial to model the complete set of all ALD reactions, hundreds of them, at the quantum mechanical level and then carefully extract the information that was needed for the growth simulations."
For the first time it is possible to see the link between atom-by-atom chemical reactions and the growth of layers of materials.
Many technologies require the deposition of materials in thin, high-quality films. Examples in the electronics field include CMOS transistors, memories (DRAM, NVM/flash) and high value capacitors for RF decoupling and signal processing. Smaller, faster and more powerful capacitors and memories can be made if the materials can be fabricated in thinner and thinner layers. More efficient sensors, fuel cells and photocatalysts can also be manufactured if active materials can be deposited in thin layers. With scaling down to nanometre-thin layers, it becomes increasingly important to process these films in a controlled way and to understand the interfaces that dominate their properties.
Atomic-scale simulation is used to find out more about properties, processing and growth of these ultra-thin films.
The simulations were made possible through the computational power of the Irish Centre for High End Computing and the project was funded by Science Foundation Ireland through the FORME strategic research cluster.
- Paul Buckley
EE Times Europe