  Time-dependent drift of resistance and threshold voltage in phase change
memory (PCM) devices is of concern as it leads to data loss. Electrical drift
in amorphous chalcogenides has been argued to be either due to electronic or
stress relaxation mechanisms. Here we show that drift in amorphized Ge2Sb2Te5
nanowires with exposed surfaces is extremely low in comparison to thin-film
devices. However, drift in stressed nanowires embedded under dielectric films
is comparable to thin-films. Our results shows that drift in PCM is due to
stress relaxation and will help in understanding and controlling drift in PCM
devices.
