Electrical wind force-driven and dislocation-templated amorphization in phase-change nanowires.
Phase-change materials undergo rapid and reversible crystalline-to-amorphous structural transformation and are being used for nonvolatile memory devices. However, the transformation mechanism remains poorly understood. We have studied the effect of electrical pulses on the crystalline-to-amorphous phase change in a single-crystalline Ge(2)Sb(2)Te(5) (GST) nanowire memory device by in situ transmission electron microscopy. We show that electrical pulses produce dislocations in crystalline GST, which become mobile and glide in the direction of hole-carrier motion. The continuous increase in the density of dislocations moving unidirectionally in the material leads to dislocation jamming, which eventually induces the crystalline-to-amorphous phase change with a sharp interface spanning the entire nanowire cross section. The dislocation-templated amorphization explains the large on/off resistance ratio of the device.
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
Sung-Wook
SW
Nam
Hee-Suk
HS
Chung
Yu Chieh
YC
Lo
Liang
L
Qi
Ju
J
Li
Ye
Y
Lu
A T Charlie
AT
Johnson
Yeonwoong
Y
Jung
Pavan
P
Nukala
Ritesh
R
Agarwal