New functionalities of TEllurium based AMorphous materials – TEAM

Amorphous telluride thin films are now present as starting material in many electronic devices and setups, and found huge applications in the phase change memory (DVD) industry. Similarly, in the aerospace industry, amorphous Te-based alloys are used for infrared integrated optics. In order to design new material functionalities for (other) future applications such as improved infrared transmitting waveguides or stable phase change data storage, there is a demanding need to understand in more detail the underlying factors which control the glass-forming tendency of tellurides and the relationship between structure and functional properties. In contrast with light chalcogenides (selenium and sulphide) however, tellurides do not form easily bulk glasses due, in part, to a high crystallization tendency and a difference in chemical bonding.

This project has four partners (LPTMC Paris, CINAM Marseille, ICG Montpellier et IM2NP Marseille) with complementary expertise, and proposes to address such issues by combining molecular simulations, topological modeling, synthesis and characterization of three important families of telluride glasses, with a special emphasis on compositional trends of physical and chemical properties. Three systems having obvious applications will be considered: Ge-Te and Ge-Sb-Te used in phase-change applications, and Ge-Ga-Te used in infrared waveguide applications.

The theoretical and experimental effort will be achieved in parallel with a deep involvement and interaction between the partners having all their own expertise which is brought into the project and represents a clear added value. At a first stage, experimental measurements on structure on selected compositions will be performed to validate the numerical schemes in the liquid phase, prior to any detailed compositional study. During a second stage guided by the theoretical predictions from topological models, it is planned to investigate compositional joins using unique synthesis facilities to prevent from crystallization (co-evaporation, twin-roller quench), in order to obtain an optimized glass-forming region. The thermal and structural properties will be characterized in this region, and analyzed with respect to the flexible to rigid transitions.

Ultimately, it is expected to find (new) functionalities of amorphous tellurides, which could derive directly from the remarkable properties found in selected compositional regions, and which are well documented in selenide and sulphide glasses.

Finally, we mention that there is also an effort in academic training as two PhD students are planned to be involved in the project.