(a) Cross-sectional STEM image, (b) simulated electron diffraction and (c) corresponding FFT pattern of the (d) Bi2GeTe4 crystal viewed in [210] direction. (e) HR-STEM image acquired at higher magnification.

Bi2GeTe4 Crystal structure

The next generation of computing will be driven by the quantum phenomena and associated technologies, where interactions of light with matter and understanding of electronic spin-charge in solids will become primary control parameters. Quantum materials will offer a robust platform for exploring and harnessing these control parameters in advanced hardware technologies. 

Chalcogenides are a class of fundamental materials which shows several interesting quantum phenomena including superconductivity, charge density wave and quantum topological nature for spintronics and quantum qubit applications. However, to observe and probe the quantum phenomena, we require extremely high quality crystalline materials for substrate as well as components of electronic device fabrications. In general, the crystalline defects such as vacancies, dislocations, interfaces and grain boundaries can influence the overall performance of the materials. Thus, to get a better understanding of the atomic arrangements in the material system, advanced electron microscopy provides direct observation of the structure at the atomic scale, providing insights into their formation mechanisms and effects on electronic transport.  

The layered Bi2GeTe4 is one of the topological quantum materials with an intriguing crystal structure made up of periodic repetition of seven layered atomic slabs separated by van der Waals gaps. Bi2GeTe4 exhibits a hierarchical layered crystalline structure with distinct chemical bonding arrangements.