On July 21st, 2017 at 02.00 pm, Dr. Raffaella Calarco will be giving a lecture on "Performance of Phase Change Memory Cells Grown by Molecular Beam Epitaxy" in DEIB Alpha Room, via Golgi 40 Milano.
Phase Change Materials (PCMs) are unique compounds employed in non-volatile random access memory thanks to the rapid and reversible transformation between the amorphous and crystalline state that display large differences in electrical and optical properties.
The semiconductor industry standard deposition of such memory cell active material is by sputtering, which guarantees the right throughput and good film control. Instead we use Molecular beam epitaxy (MBE), a well known growth technique that offers unique advantages such as superior thickness control, ultrahigh purity and the possibility of using a variety of in-situ characterization tools for process control.
By MBE after proper deposition optimization we improve the film and interface quality and are able to get an impressive crystalline quality demonstrating the feasibility of using MBE for fabricating memory device that are in-line with industrial standards . MBE also offers a high degree of control of the deposition rates of individual elements. This aspect makes the technique attractive for studying chalcogenide superlattices (GeTe-Sb 2 Te 3) which are under intense investigation for non-volatile memory applications. Although the programming current of PCM memory can be reduced by 1/3 using superlattices the switching mechanism is still debated in literature. I will offer new insights, obtained using ultrafast THz dynamic studies, which might pave the way to the clarification of such mechanism.
The seminary will also be the opportunity to introduce the Paul-Drude- Institut and its running activities.
 J.E. Boschker et al. Appl. Phys. Lett. 106, 023117 (2015)