Hot Electrons in Amorphous Silicon

At extremely high electric fields $(F\le 0.55\mathrm{MV}/\mathrm{cm})$ and high temperatures $(300<T<\mathrm{}450\mathrm{K})$, full deactivation of the electron drift mobility in amorphous hydrogenated silicon $(a-\mathrm{S}\mathrm{i}:\mathrm{H})$ is obtained and therefore the shallow trapping is substantially reduced. New data clearly demonstrate that the free electron (band) mobility in $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ decreases when the electric field increases, contrary to other disordered materials (e.g., amorphous selenium). In this sense the free carrier transport in $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ is similar to the hot carriers in crystals when phonon scattering prevails.