(IMAGE) Forschungszentrum Juelich Caption By varying the thickness of the layers of semiconductor sandwiches made from silicon (grey area), bismuth-telluride, an n-type semiconductor (red area) and antimony telluride, a p-type semiconductor (green), topological insulators can be customized according to needs, as shown by the experiments conducted by researchers from Jülich and Aachen. The quality of the layers they produced using molecular beam epitaxy were verified by ultra high-resolution scanning electron microscopy. The atomic layers are clearly visible on the left side of the cube's edge. Credit Forschungszentrum Jülich Usage Restrictions Image may only be used with approprate credit. Image may only be used in conjunction with media reports about Forschungszentrum Jülich. 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.