Photoconductivity during 30 ns laser pulses in "a-Si:H"

The photoconductivity, σ_p(t), of intrinsic and compensated hydrogenated amorphous silicon (a-Si:H) was measured at room temperature with nanosecond time resolution during 30 ns long laser pulses of 650 nm wavelength and pulse energies, P, between 35 mJ/cm₂ and 2 μJ/cm₂. For larger P the response time of σ_p is faster than 1 ns and σ_p = cP^1/2 with the same c value for all samples studied, independent of defect concentration, N_D. Deviations from this bimolecular recombination law begin when the total steady state photocarrier concentration becomes comparable to or less than N_D.