Far infrared spectroscopy of thin film chalcogenides for emerging memory technologies

Groep: DiSC

Promotor: Prof. Henk Vrielinck

Begeleiding: Dr. Samira Khelifi

Inlichtingen: tel. 09/264.43.56 of email henk.vrielinck@ugent.be


Chalcogenides are materials that contain one of the elements S, Se and/or Te. These materials find applications in several areas like thin film solar cells, optical components and (emerging) memory technologies. For the latter, Ge-Sb-Te is a well-known material that has been used in the past in rewritable optical disks. Nowadays, Ge-Sb-Te (and several modifications) is used in phase change resistive memories (PCM) [1]. Some chalcogenides show “volatile” threshold switching [2] (i.e. conducting for a voltage above a certain threshold and non-conductive at lower voltage) rather than “non-volatile” memory switching. These materials are of high interest for a selector element, which is placed in series with the memory element to enable integration in dense memory arrays. The characterization of the structure of these materials is of key importance to understand their properties, and to optimize the performance of these materials as memory or selector element.


In this thesis, the aim is to explore Fourier Transform Infrared Spectroscopy in the Far Infrared (FIR-FTIR) to study the occurrence of specific bonds in thin film chalcogenides. In a first step, different stacks containing these materials will be characterized and compared, and the modelling for data extraction will be optimized. From this study, the optimal stack and measurement conditions will be selected. In a next step, different chalcogenide films will be analysed in order to link the occurrence/absence of bonds to composition and post deposition treatments. In order to gain further insight in the material, there is the possibility to submit the samples for complementary analysis like Raman spectroscopy at imec.  

The thesis is in collaboration with imec. The purpose is to interact with the materials researchers to define and setup the different stacks to be studied, and to get access to complementary analysis techniques, if needed.

Educatieve master: Dit onderwerp wordt niet aangeboden in de educatieve master.

Mobiliteit: Dit onderwerp biedt geen directe mogelijkheden voor mobiliteit.

[1] D. Lencer, M. Salinga, and M. Wuttig, “Design Rules for Phase-Change Materials in Data Storage Applications,” Adv. Mater., vol. 23, no. 18, pp. 2030–2058, 2011.

[2] A. Velea et al., “Te-based chalcogenide materials for selector applications,” Scientific Reports, vol. 7, no. 1, p. 8103–, 2017.