학술논문
Direct Evidence for Abrupt Postcrystallization Germanium Precipitation in Thin Phase-Change Films of Sb-15 at. % Ge
Document Type
Journal Article
Author
Source
Applied Physics Letters; 93
Subject
Language
English
ISSN
0003-6951
Abstract
We present evidence for the instability in the crystalline (metallic) state of binary Te-free phase-change Ge-Sb thin films considered for integration into nonvolatile nanosized memory cells. We find that while the amorphous (semiconducting) phase of eutectic Sb-15 at. % Ge is very robust until Sb crystallization at 240 C, at about 350 C, germanium rapidly precipitates out. Ge precipitation, visualized directly with transmission electron microscopy, is exothermic and is found to affect the films' reflectivity, resistance, and stress. It converts melting into a two-step process, which may seriously impact the switching reliability of a device.