The transport properties of polycrystalline silicon films are examined and interpreted in terms of a modified grain-boundary trapping model. The theory has been developed on the assumption of both a δ-shaped and a uniform energy distribution of interface states. A comparison with experiments indicates that the interface states are nearly monovalent and peaked at midgap. Their density is 3.8×1012 cm−2, in accordance with carrier-lifetime measurements performed on CVD films.

We present the data on temporal (t) drift of parameters in chalcogenide phase change memory that significantly complement the earlier published results. The threshold voltage Vth and the amorphous state resistance R are shown to drift as ΔVth∝v ln t and R∝tα in broad intervals spanning up to nine decades in time; the drift coefficient v depends on glass parameters and temperature, but does not depend on device thickness. We have demonstrated that drift saturates at long enough times that can be shorten with temperature increase. All available data on drift dynamics are fully consistent with the classical double-well-potential model, which gives simple analytical expressions for the observed temporal dependencies including numerical parameters.

Experimental data on switching in phase change memory testify in favor of its underlying nucleation mechanism with field dependent nucleation barrier. Similar to the standard nucleation, switching occurs after exponentially long delay time when the conditions are not favorable enough, e.g., the nucleation barrier not low or the temperature not high enough. The switching statistics is found to be consistent with the nucleation mechanism as well. A theoretical model of nucleation switching is outlined.