A major advance in creating a tuneable high-quality thin film chalcogenide perovskites

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"MIT engineers report creating the first high-quality thin films of a new family of semiconductor materials. ...
Chalcogenide perovskites were made as early as the 1950s by French chemists. Similar work was repeated in the 80s and early 90s, but “the idea that these materials would be useful semiconductors didn’t come along until the early 2010s ...

Jaramillo and colleagues used a technique called molecular beam epitaxy (MBE) to grow their high-quality films. The technique allows atomic-level control over crystal growth ... 

As its name implies, MBE essentially points beams of molecules at a specific arrangement of atoms on a surface (“taxy,” as in epitaxy, means arrangement, or orientation). That arrangement of atoms provides a template for the beamed molecules to grow on. “That’s why epitaxial growth gives you the highest-quality films. The materials know how to grow,” ..."

From the abstract:

"The making of BaZrS3 thin films by molecular beam epitaxy (MBE) is demonstrated. BaZrS3 forms in the orthorhombic distorted-perovskite structure with corner-sharing ZrS6 octahedra. The single-step MBE process results in films smooth on the atomic scale, with near-perfect BaZrS3 stoichiometry and an atomically sharp interface with the LaAlO3 substrate. The films grow epitaxially via two competing growth modes: buffered epitaxy, with a self-assembled interface layer that relieves the epitaxial strain, and direct epitaxy, with rotated-cube-on-cube growth that accommodates the large lattice constant mismatch between the oxide and the sulfide perovskites. This work sets the stage for developing chalcogenide perovskites as a family of semiconductor alloys with properties that can be tuned with strain and composition in high-quality epitaxial thin films, as has been long-established for other systems including Si-Ge, III-Vs, and II-VIs. ..."

Engineers report a major advance in creating a new family of semiconductor materials | MIT News | Massachusetts Institute of Technology Ultrastable and made of inexpensive, nontoxic elements, chalcogenide perovskites could find applications in solar cells, lighting, and more.

Making BaZrS3 Chalcogenide Perovskite Thin Films by Molecular Beam Epitaxy (no public access)