Dangling Bond Creation in Hydrogenated Amorphous Silicon by Light-Soaking

It has been observed in glow-discharged undoped amorphous hydrogenated silicon (a–Si:H) films that the Fermi level position moves downwards and is pinned near the midgap by a low dose irradiation with gamma-rays. Films irradiated lightly with gamma-rays offer an opportunity for investigating Staebler-Wronski effect without any ambiguity due to Fermi level shift. Under the condition of the pinned Fermi level, we have confirmed a decrease in the electron lifetime and in parallel an increase in the ESR spin density relating to neutral Si dangling bonds after light-soaking.