"Acceleration of Crystallization Kinetics in Ge-Sb-Te-Based Phase-Change Materials by Substitution of Ge by Sn"

Peter Zalden: Christine Koch, Melf Paulsen, Marco Esters, David C. Johnson, Matthias Wuttig, Aaron M. Lindenberg, Wolfgang Bensch; Advanced Functional Materials, 09/28/20.

Additional Authors: Christine Koch, Melf Paulsen, Marco Esters, David C. Johnson, Matthias Wuttig, Aaron M. Lindenberg, Wolfgang Bensch

Abstract:

Thin films of (Ge1–xSnx)8Sb2Te11 are prepared to study the impact of Sn-substitution on properties relevant for application in phase-change memory, a next-generation electronic data storage technology. It is expected that substitution decreases the crystallization temperature, but it is not known how the maximum crystallization rate is affected. Ge8Sb2Te11 is chosen from the (GeTe)y(Sb2Te3)1–y system of phase-change materials as a starting point due to its higher crystallization temperature as compared to the common material Ge2Sb2Te5. In situ X-ray diffraction at 5 K min−1 heating rate is performed to determine the crystallization temperature and the resulting structure. To measure the maximum crystallization rate, femtosecond optical pulses that heat the material repetitively and monitor the resulting increase of optical reflectance are used. Glasses over the entire composition range are prepared using a melt-quenching process. While at x = 0, 97, subsequent pulses are required for crystallization, one single pulse is enough to achieve the same effect at x = 0.5. The samples are further characterized by optical ellipsometry and calorimetry. The combined electrical and optical contrast and the ability to cycle between states with single femtosecond pulses renders Ge4Sn4Sb2Te11 promising for photonics applications.