Graphene Bubble Formation and Appearance (IMAGE) Institute for Basic Science Caption Bubbles form when molecules are trapped between the graphene sheet and the silica (SiO2/Si) substrate. The image shows also the hottest spot in red, which corresponds to the highest part of the bubble. Credit IBS Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.