Electrical resistance and structural changes on crystallization process of amorphous Ge-Te thin films

摘要

The electrical resistance and structural changes on the crystallization process of sputter-deposited amorphous Ge_(100-x)Te_x (x: 46-94) were investigated by two-point probe method. It was found that stoichiometric GeTe amorphous film crystallizes into rhombohedral GeTe single phase, which leads to a large electrical resistance drop, while off-stoichiometric Ge-Te amorphous films show two-stage crystallization or phase separation via single crystalline phase. Especially, Ge_(33)Te_(67) amorphous film crystallizes first into metastable GeTe2 single phase and then decomposes into α-GeTe and Te two-phase with a large electrical resistance change. The first crystallization temperature strongly depends on the composition. The Ge_(33)Te_(67) film shows the highest crystallization temperature and activation energy for the first crystallization in the film with Te-rich composition.