Studying materials at nanoscale using Transmission Electron Microscopy

Transmission electron microscopy (TEM) plays an important role to study materials in depth at or below the nanometer length scale. Two different interesting examples of this kind will be presented in this seminar.

I) Topological insulator Bi2Se3 recently came into the limelight by showing superconductivity when doped with Cu and was postulated that Cu intercalation into Bi2Se3 structure is the main reason behind this superconducting behavior. It was also reported that any long or short range ordering in Cu intercalation was absent in the bulk material so, in other words Cu intercalated regions of nanometer size range are distributed within bulk Bi2Se3 matrix. Using TEM the presence of intercalated structure at nanoscale within the bulk Bi2Se3 matrix was revealed. Stoichiometry of the intercalated unit cell was also calculated from the projected potential. 

II) Structure and chemistry across the interfaces of a Ge quantum well embedded within rare earth oxide layers grown on p-Si (111) substrate using encapsulated solid phase epitaxy method have been studied at nano scale using different TEM methods. Results demonstrate the structural and chemical abruptness of both the interfaces which is most essential to maintain the desired quantum barrier structure.