R&D: Tuning Crystallization Pathways in Ge-Rich GST Alloys, The Influence of Nitrogen and Hydrogen

Physica Status Solidi (RRL) – Rapid Research Letters has published an article written by Jacopo Remondina, Aix Marseille Univ, Université de Toulon, CNRS, IM2NP, Campus Scientifique de St. Jérôme, 13013 Marseille, France, Eloïse Rahier,  Minh-Anh Luong, Nicolas Ratel-Ramond, CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse, France, Sijia Ran, CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse, France, David Grosso, Aix Marseille Univ, CNRS, CINaM, Marseille, France, Cristian Mocuta, Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin – BP 48, 91192 Gif-sur-Yvette Cedex, France, Alain Portavoce, Aix Marseille Univ, Université de Toulon, CNRS, IM2NP, Campus Scientifique de St. Jérôme, 13013 Marseille, France, Yannick Le Friec, Daniel Benoit, STMicroelectronics, 850 rue Jean Monnet, 38920 Crolles, France, Elisa Petroni, Smart Power Technology R&D, STMicroelectronics, Agrate Brianza, Italy, Alain Claverie, CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse, France, and Magali Putero, Aix Marseille Univ, Université de Toulon, CNRS, IM2NP, Campus Scientifique de St. Jérôme, 13013 Marseille, France.

Abstract: “This study investigates the effects of nitrogen and hydrogen doping on the crystallization mechanisms of Ge-rich GST (GGST) alloys, widely used in phase-change memory applications. Using in situ synchrotron X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and thermal desorption spectroscopy, this article examines undoped, nitrogen-doped, and co-doped (N + H) GGST samples to understand their structural and kinetics transformations during thermal treatments. Nitrogen doping significantly increases the crystallization temperature and enhances thermal stability, while reducing grain sizes and modifying kinetics. Hydrogen shows a contrasting effect. Alone, it minimally impacts crystallization temperatures but decreases activation energy and promotes heterogeneous nucleation, mediated by transient GeTe Pnma phase. However, combined with nitrogen, hydrogen disrupts the formation of GeN bonds, favoring NH interactions instead. This suppresses nitrogen effects while introducing interface-driven crystallization mechanism. The findings provide new insight into dopant interactions within GGST alloys, demonstrating the potential of co-doping strategies to fine-tune phase change behavior. The study underscores the need for further exploration of dopant combinations to achieve enhanced stability and performance, particularly for memory devices operating in harsh environments.“