Resolving glass transition in Te-based phase-change materials by modulated differential scanning calorimetry

Abstract

Glass transitions of Te-based phase-change materials (PCMs) were studied by modulated differential scanning calorimetry. It was found that both Ge 2 Sb 2 Te 5 and GeTe are marginal glass formers with ΔT (= T x % T g ) less than 2.1°C when the heating rate is below 3°C min %1. The fragilities of Ge 2 Sb 2 Te 5 and GeTe can be estimated as 46.0 and 39.7, respectively, around the glass transition temperature, implying that a fragile-to-strong transition would be presented in such Te-based PCMs. The above results provide direct experimental evidence to support the investigation of crystallization kinetics in supercooled liquid PCMs.

Electrical tuning of phase-change antennas and metasurfaces

“…Set pulses of a 1 μs duration and with a 20 μs trailing time are used to heat the GST above the crystallization temperature (Tx) and then maintain the high temperature long enough to facilitate complete crystallization. 33,55 Reset pulses feature a higher current for a shorter duration of 500 ns to rapidly raise the local temperature above the melting temperature of GST (Tmelt ~600 °C). The pulse is then switched off quickly with a 20 ns trailing time to achieve an effective melt-quench that freezes in the amorphous phase.…”

Phase change thin films for non-volatile memory applications

“…The transition temperature is strongly dependent on the heating rate, interfaces and composition of the particular alloy. 26,63,64…”

“…23 However, since phase change alloys are poor glass formers, rapid cooling rates are required to suppress the recrystallization of the alloy when it is to be amorphized. 17,[24][25][26][27] This can be achieved by appropriate device design. Moreover, the long-term stability of phase change materials is an issue and has to be improved by materials design.…”

Approaching the Glass Transition Temperature of GeTe by Crystallizing Ge15Te85

“…Unfortunately, values of T g for GeTe reported in literature vary from as low as 150 C up to 230 C. [16][17][18][19][20][21] This large variation results in a large and unfavorable uncertainty when it comes to predicting crystallization kinetics for PCM-based data storage devices. For this reason, an accurate value based on experimental data for the glass transition temperature T g of GeTe is highly desirable.…”