Ultra-fast learning
Autobot has discovered that high quality films can be synthesized at relative humidity levels of 5-25% by carefully tuning the other three synthesis parameters.
“This humidity range does not require strict environmental management,” said Ansuman Halder, a postdoctoral researcher at Berkeley Lab and co-first author of the research paper. “This discovery lays an important foundation for the development of commercial manufacturing facilities.”
Another insight was that humidity levels above 25% destabilizing the material during the deposition process, resulting in poor film quality. The team explained and validated this finding by performing manual photoluminescence spectroscopy during film integration.
Autobot's performance was impressive. By identifying the most useful experiments, the algorithm quickly learned how the synthetic parameters affect film quality.
“This powerful performance was demonstrated by a dramatic decline in the learning rate of the algorithm after Autobot sampled less than 1% of the combinations of over 5,000 parameters,” says Maher Alghalayini, a postdoctoral scholar and co-author at Berkeley Lab. “In the new experiment, we decided to stop running the experiment because we have not changed the material quality predictions of the algorithm at this point.”
An innovative aspect of this research was the “multimodal data fusion.” This was done using a variety of data science and mathematical tools to integrate different data sets and images from three characterization techniques into a single metric for material quality. The idea was to quantify the results and make them usable by machine learning algorithms. For example, a collaborator at the University of Washington designed an approach to convert photoluminescent images into a single number based on how light intensity changes across images.
This study was supported by the Department of Energy's Science Bureau and was part of the Department of Science's Early Career Research Program.
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The Lawrence Berkeley National Laboratory (Berkeley Lab) is committed to groundbreaking research focusing on discovery science and solutions for a rich and reliable energy supply. Lab's expertise spans materials, chemistry, physics, biology, earth and environmental science, mathematics, and computing. Researchers around the world rely on the lab's world-class scientific facilities for their own pioneering research. It was founded in 1931 with the belief that the biggest issues are best dealt with by teams. The Berkeley Lab and its scientists are recognized by 16 Nobel Prizes. Berkeley Lab is a multiprogram national laboratory managed by the Department of Energy Science and Sciences, University of California.
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