Thermal metastability in bulk and thin film chalcogenide glasses is st
udied by measuring conductivity after cooling them at different rates
from a temperature higher than their glass transition temperature, T(g
). No changes are observed for the two chalcogenides studied. In contr
ast, the phosphorus doped a-Si:H films show a large effect, with equil
ibration temperature T(E) close to T(g). This surprising absence of th
e thermal metastability in chalcogenide glasses is discussed in terms
of hydrogen glass model for a-Si:H and is attributed to the absence of
hydrogen in chalcogenides.