Effect of the charge state of defects on the light-induced kinetics of the photoconductivity of amorphous hydrated silicon

The photoconductivity and defect density in films of nondoped a-Si:H soaked with light (W=114 mW/cm², λ<0.9 μm) for 5 h were investigated. It is shown that σ_ph ~ t ^-γ and N _D ~ t ^β, where γ>β or γ⋍β, depending on the position of the Fermi level prior to light soaking, i.e., depending on the charge state of the defects: D ⁻ and D ⁰ or D ⁺ and D ⁰. It is also shown that the light-induced kinetics of σ _ph is affected by a transition of the defects into the D ⁰ state because of a corresponding shift of the Fermi level during light soaking. Fiz. Tekh. Poluprovodn. 32, 345–348 (March 1998)