  We emphasize the role of temperature in explaining the IV ovonic threshold
switching curve of amorphous phase change materials. The Poole-Frankel
conduction model is supplemented by considering effects of temperature on the
conductivity in amorphous materials and we find agreement with a wide variety
of available data. This leads to a simple explanation of the snapback in
threshold switching. We also argue that low frequency current noise in the
amorphous state originates from trains of moving charge carriers derailing and
restarting due to the different local structures within the amorphous material.
