Magnetic Field Dependence of the Photoconductivity in Amorphous Silicon

We report the first observation of magnetic field induced changes in the photoconductivity σ p of a‐Si produced by the glow discharge technique. The relative change of σ p in fields H 0 up to 10 kG is of the order of 1%. The dependence of σ p on the magnitude of H 0 is similar to that of the dark conductivity in evaporated a‐Si and a‐Ge, suggesting that the same type of mechanism is responsible for both phenomena. We explain the change of σ p in terms of a spin dependent pair recombination model in which the recombination rate of triplet pairs is correlated with the spin relaxation rate which depends on the applied magnetic field H 0 .