Characterization of low temperature crystal growth parameters of the growth-dominated phase change materials GeSb6Te

Abstract

Phase change memory materials are semiconducting alloys used in optical- and resistivity-based memory devices that have large differences in optoelectronic properties between the amorphous and crystalline states. Alloys for memory applications must have a low crystallization rate at service temperatures so the written memory remains stable for long times. GeSb6Te may be attractive for use because of its rapid crystallization at high temperatures, but its low temperature crystallization behavior has not been fully assessed. Here, the crystallization parameters of amorphous films of GeSb6Te are characterized using in-situ hot stage optical microscopy under isothermal conditions for temperatures ranging from 185 °C to 195 °C. Individual grain sizes were tracked as well as the percent of material crystallized, from which the direct measurement of the crystal growth rate and Johnson-Mehl-Avrami-Kolmogorov parameters were calculated. GeSb6Te was found to have comparable growth and crystallization rates in the low temperature region as other growth-dominated phase change materials.