Crystallization and thermal stability of Sn-doped Ge₂Sb₂Te₅phase change material

Abstract

The influence of Sn doping on the crystallization and thermal stability of Ge2Sb2Te5 phase change material was studied. Thermal analysis shows that the phase change of Sn7.0Ge20.6Sb20.7Te51.7 occurs slightly higher than that of Ge2Sb2Te5 at 154 °C and has a lower melting point at 536 °C. The activation energy for crystallization for this material is also higher. It has a face-centred-cubic crystal structure. A fast crystallization speed of 60 ns is realized upon irradiation by a blue laser beam of 405 nm. The use of the Sn7.0Ge20.6Sb20.7Te51.7 phase change material as a mask layer in aperture-type super-resolution near-field phase change disk is realized to increase the carrier-to-noise ratio and thermal stability.

A zero density change phase change memory material: GeTe-O structural characteristics upon crystallisation

“…Secondly, as a general feature of phase change materials, there is a severe volume shrinkage (6.5%–9.6%910) and corresponding increase in mass density upon crystallisation, which applies considerable mechanical stresses in the PCM cells11, and consequently, causes resistance drift and void formation in the device that finally limits the cyclability of the memory cells. In order to address these issues, other elements including nitrogen12, oxygen13, silicon14, tin15, carbon6, and tungsten16 as well as oxides such as SiO 2 17and Ta 2 O 5 18have been incorporated into the Ge 2 Sb 2 Te 5 material, leading to a higher crystallisation temperature with longer retention times and a reduced residual stress with smaller density change during the phase transition1018.…”

Ge 2 Sb 2 Te 5 /SnSe 2 nanocomposite multilayer thin films for phase change memory application

“…Fig. 3 shows the curves of sheet resistance versus time at various isothermal annealing temperature for [Ge 2 Sb 2 Te 5 (4 nm)/SnSe 2 (10 nm)] 7 and Arrhenius plot of data retention based on different Ge 2 Sb 2 Te 5 /SnSe 2 films showing extrapolated temperature for 10 years data retention. It can be seen that the higher isothermal annealing temperature leads to shorter failure time, which means that the crystalline grain growth in phase change process is faster.…”

“…And the pump power of all the curves is 15 mW. Each curve is measured based on different spots on the surface of the same sample of amorphous [Ge 2 Sb 2 Te 5 (4 nm)/SnSe2 (10 nm)] 7 film to ensure that all the measurements were taken under the same condition. The increasing laser-irradiation power is from 20 to 44 mW.…”

“…The distinguishing feature of these two phases mainly utilizes the difference of resistance between two states which can be easily measured by electrical methods. Nowadays, scientists mostly pay their attention on Ge-Sb-Te system in phase change materials since Ge 2 Sb 2 Te 5 is the most mature product [5][6][7] which can be applied to practical devices, not to mention Ge 2 Sb 2 Te 5 itself. Researchers adopted many methods to improve its performance.…”

Phase change behaviors of Zn-doped Ge2Sb2Te5 films

“…It has been reported that a relatively weak bonding strength can cause a significant increase of the crystallization speed in phase change materials. [11][12][13] For example, Ge-Te has a bond energy of 397 kJ/mol that is larger than Sn-Te bond (359 kJ/mol). Therefore replacement of Ge-Te by Sn-Te with weak bonding energy will increase the crystallization speed.…”