Atomic Structure Transformations of C-Doped Ge2Sb2Te5 Using In-Situ X-Ray Scattering

Conference: 2022: 72nd ACA Annual Meeting
John Langhout Poster Author
University of Florida
Gainesville, FL 
Danielle Alverson Additional Author
University of Florida
Megan Butala Additional Author
University of Florida
Gainesville, FL 
07/31/2022: 5:30 PM - 7:30 PM
Poster Session 
Portland Marriott Downtown Waterfront 
Room: Exhibit Hall 


Phase change materials (PCMs) are characterized by their fast transformation speeds from their amorphous to crystalline states, with each state having distinct properties. These unique and distinct properties can be used for data storage and even computation, with their proposed application to enable neuromorphic computing. Ge2Sb2Te5 (GST) is a widely used PCM due to its fast-switching speeds and good data storage capabilities. However, it also has a low crystallization temperature, which makes long-term data storage (>10 years) difficult. One way to improve this is to alloy the material with carbon, which has been found to increase both the transformation temperature and the stability of the cubic phase.
To understand the effects of carbon, we are investigating how atomic structure transformations are modified by carbon doping (from 0% to 12%, molar) via in situ X-ray scattering, including X-ray diffraction (XRD) and pair distribution function (PDF) analysis. These methods provide access across local, mid-range, and average structure scales, and variations thereof through their amorphous-to-crystalline transformation. By identifying this atomic structure over the process, we can establish structure-property relationships and how these vary with composition. This new understanding is necessary to tailor GST, or other PCMs, for current and future applications, such as data storage and computing.

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.