Glass transition of the phase change material AIST and its impact on crystallization. (1st November 2021)

• Record Type: Journal Article
• Authors: Pries, Julian; Sehringer, Julia Charlotte; Wei, Shuai; Lucas, Pierre; Wuttig, Matthias
• Is Part Of: Materials science in semiconductor processing. Volume 134(2021)
• Publication Date: 2021-11-01
• Subjects: Crystallization kinetics -- Glass transition temperature -- Structural relaxation -- Ultrafast differential scanning calorimetry (FDSC) -- Phase change materials -- Metavalent bonding; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2021.105990
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: Engineering phase change materials (PCM) to realize superior data storage devices requires a detailed understanding of crystallization kinetics and its temperature dependence. The temperature dependence of crystallization differs distinctly between crystallizing from the glassy phase and the undercooled liquid (UCL). Hence, knowing the phase from which crystallization occurs is necessary for predicting the switching ability. Here, we measure the glassy dynamics and crystallization kinetics using calorimetry for heating rates spanning over six orders of magnitude. Our results show that the prominent PCM (Ag, In)-doped Sb2 Te (AIST) exhibits a change from crystallizing from the glassy phase to crystallizing from the UCL at a critical heating rate of 5000 K/s. Above the glass transition, the activation energy of crystallization changes drastically enabling rapid crystallization at elevated temperatures. Graphical abstract: Calorimetric data on the excess heat capacity C p exc and the crystallization peak temperature T p is combined to identify the amorphous state the phase change material AIST crystallizes from, i.e. the glassy phase or the undercooled liquid. When glass transition and crystallization interfere, the Kissinger activation energy E k drops by more than threefold, enabling rapid crystallization. The glass transition temperature T g is estimated to be about 182.5 °C. Hence, at conventional heating rates, AIST unconventionally crystallizes ~ 27.5 °C below the actual glass transition. Image 1