Exodiffusion of hydrogen in amorphous silicon

The exodiffusion of hydrogen in a-Si prepared by silane decomposition has been previously studied using H(B11,α)αα nuclear reaction and conductivity measurements which show that it takes place in two stages, one centered at 723 K, the other at 853 K. The first stage is due to the diffusion of 'weakly' bond H. The second stage which we study quantitatively here by EPR, has an activation energy of 3.6 eV corresponding to the liberation of a bond hydrogen. The fact that the EPR signal is related to the second stage governed by a process whose activation energy is equal to the Si-H bond energy is a direct evidence that the EPR signal is associated with dangling bonds which were saturated by hydrogen. (orig.)