Linnaeus Physics Colloquium: Molecular Beam Epitaxy – a way to fabricate and control crystalline materials at the nano-scale

Föreläsare: Dr Janusz Sadowski, gästprofessor vid institutionen för fysik och elektroteknik, Linnéuniversitetet; MAX IV-laboratoriet, Lunds universitet
Titel: Molecular Beam Epitaxy – a way to fabricate and control crystalline materials at the nano-scale

Plats: Kalmar – sal N1002, Norrgård. Växjö – via länk, rum D0073, hus D. Live – via Adobe Connect, https://connect.sunet.se/cmp-kalmar.

Kaffe och bullar kl 13.45 på Norrgård, rum N1002.

Illustration: Vänster – schematic view of the MBE growth chamber and the idea of the epitaxial growth process. Höger – photograph of the actual MBE growth chamber acquired by Linnaeus University.

Abstract

The term epitaxy is a combination of two Greek words: epi (upon, over) and taxis (arrangement, ordered manner). In the field of science and technology it means the formation of a thin crystalline material (layer) of particular orientation on top of another crystal (substrate).

Molecular beam epitaxy (MBE) was invented in the late sixties of the last century by a group of physicists working at Bell Labs, US (J.R. Arthur, A. Cho). It relies on generating beams of atoms or molecules in ultra-high vacuum chamber, their reaction at the heated substrate plate, and the built-up of an ordered crystalline layer on the substrate. After its introduction MBE became quickly a technique used to fabricate structures with unique physical properties, contributing to three Nobel Prizes in physics (L. Esaki in 1973; Laughlin, Störmer and Tsui in 1998; H. Kroemer in 2000).

Among different epitaxy techniques Molecular Beam Epitaxy is the one yielding materials of the highest purity. It enables combinations of different materials and extremely precise in-situ control of the deposition process, up to the level of single layers of atoms or molecules. Due to its unique features, MBE is perfectly suited for the investigation of new materials. Indeed the so-called topological materials which are presently the hottest topic in condensed matter physics are nowadays, to large extent, fabricated by MBE.

Over the last decade the use of patterned substrates has also enabled the use of MBE (and other epitaxial techniques) for the fabrication of 3-dimensional nanostructures, paving the way to the formation of fully 3-dimensional nanoscale electronic circuits.

In my talk I will briefly explain the basic features of MBE, in comparison to other epitaxy techniques, and show some examples of nanostructures which can be fabricated with the use of the MBE system relocated in 2016 from MAX-Lab Lund to Linnaeus University.