R.F. power dependence of the Staebler-Wronski effect

Abstract

The Staebler-Wronski effect has been investigated in glow-discharge-deposited hydrogenated amorphous silicon films (about 1 μm thick) grown at different r.f. powers. The samples, exposed to visible light of intensity 350 mW cm −2, showed a change, in both the activation energies for conduction and the pre-exponential factors. The activation energies changed from 0.83–1.05 eV in as-deposited annealed films to 1.03–1.15 eV for exposed films whereas the changes in the pre-exponential factors were from 5.0 × 10 4−4.3 × 10 7 Ω −1 cm −1 to 9.3 × 10 5−2.3 × 10 7 Ω −1 cm −1. Both of the constants for Meyer-Neldel rule also showed a change from 3.46 × 10 −7 Ω −1 cm −1 and 30.91 eV −1 to 1.23 × 10 −10 Ω −1 c −1 and 36.62 eV −1. The pre-exponential factors and the activation energies showed a peak for films deposited at 50 W and the rate of change of the density of dangling bonds with illumination time showed a minimum for the same film. The changes in dark conductivity and photoconductivities from the annealed to the exposed state were found to be at a maximum for samples deposited at 5 W.