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Molecular Beam Epitaxy combined with in-situ ARPES

A schematic of the MBE set-up connected to a laser ARPES system

The drive towards studying thin films has been spurred by the discovery of materials such as topological insulators, thin film superconductors, and oxide heterostructures, which possess novel electronic properties not seen in the bulk. To this end, we have installed a molecular beam epitaxy (MBE) chamber to our basement laser ARPES system. The system is capable of storing up to 8 elements, using 4 effusion cells and a 4-pocket electron-beam evaporator. Both the MBE and ARPES chamber are maintained at a pressure in the low 10-11 torr scales, allowing us to effectively study films in-situ. Recently, we have demonstrated the viability of using a cracker effusion cell to grow high quality films of the topological insulators bismuth telluride and bismuth selenide [1].

Using a vacuum suitcase designed by Dr. Felix Schmitt, we can also transfer samples in ultra-high-vacuum to the ARPES endstation at Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC. This gives us the ability to study a larger momentum space in our materials due to the availability of high-energy photons. This also enables us to explore photon energy dependence of band dispersions since we can vary photon energies in a synchrotron ARPES light source.

In summary, our experimental setup provides a clean and comprehensive system upon which we can study the effects of dimensional constraints and interface effects with the aim of both furthering our understanding of condensed matter physics and discovering new materials.

Selected Publications

[1] J. J. Lee et al. Intrinsic ultrathin topological insulators grown via molecular beam epitaxy characterized by in-situ angle resolved photoemission spectroscopy. Appl. Phys. Lett. 101, 013118 (2012)