C4 Effects of nanoscale confinement on the properties of phase change materials

In project C4 (2019-2023) we will investigate how nanoscale confinement changes the behavior of phase change materials, especially their electrical and structural properties. Newly developed devices will allow analyzing one-dimensional confinement as narrow as a few nanometers, were even a monatomic material like antimony can be stabilized against immediate crystallization by strong spatial confinement. Such devices provide ideal means for the quantification of the temperature dependent crystallization kinetics, electrical resistivity and its temporal evolution as a function of confinement. The ultimate experimental investigations will be based on three-dimensionally highly confined volumes of phase change material are nanoparticles as they will be synthesized in project C1.

Design, fabrication and microscopic analysis of nanoscale devices

Critical physical phenomena in phase-change based resistive switching devices, like threshold switching or crystallization kinetics, must ultimately be analyzed in their technologically relevant manifestation, i.e. in nanoscale devices. To this aim, electrically switchable lateral devices are manufactured employing lithographic means. Furthermore, advanced test structures are designed around established devices in order to enable unprecedented investigations of the dynamic processes using in operando electron microscopy techniques and rapid annealing schemes. Necessary fabrication procedures are developed, sample series are produced and devices are microscopically analyzed before and after electrical characterization.


Design, fabrication and compositional analysis of phase change

E-beam lithography and focused ion beam is being used together with sputter deposition and thermal evaporation for rapidly prototyping lateral, optically accessible cell structures, which are useful for the investigation of material dependent switching characteristics. In addition, the FIB/SEM tool is being used for the analysis of samples both immediately after their fabrication to check their integrity and after experiments have been performed on them to investigate what happens to the cell upon switching. Furthermore, a 3D-atomprobe is being employed to gain insight into the elemental distribution in a cell, quantitatively addressing issues such as interface integrity, diffusion, formation of filaments, electro-migration, etc.

Principal investigator:

Dr. rer. nat. M. Salinga
I.Physikalisches Institut IA
RWTH Aachen University
Phone: +49 (0)241 80 27178
E-mail: martin.salinga@physik.rwth-aachen.de