Hydrogen evolution from annealed samples of amorphous Si-H alloys was examined. From the results of isothermal annealing experiments, it was demonstrated that, at fairly low temperatures (≈225C), the rate-limiting step for H evolution was a singly-activated desorption process with a free energy of activation of 1.7eV. It was shown that this low-temperature evolution was not limited by diffusion of H through the Si network. For this low-temperature desorption process, an activation enthalpy of 0.4eV and an activation free energy of 1.7eV were measured in isochronal annealing experiments. Also observed was evolution of H which was associated with crystallization that occurred near to 600C and, in some samples, an intermediate temperature desorption process near to 500C that involved a free energy and enthalpy of activation of 2.4eV and 1.6eV, respectively.

Kinetic Analysis of Hydrogen Evolution from Reactively Sputtered Amorphous Silicon-Hydrogen Alloys. S.Oguz, M.A.Paesler: Physical Review B, 1980, 22, 6213