Increase in photoconductivity of polycrystalline silicon by plasma annealing

Absorption coefficient and photoconductivity of CVD prepared polycrystalline silicon were measured in the photon energy range between 0.6 and 2.4 eV. The photoconductivity is increased by plasma hydrogen annealing at 300 °C by a factor of more than 1000 to about 10−3 (Ω cm)−1/1015 photons cm−2 sec−1 at 2 eV. Beyond 1 eV the absorption coefficient is scarcely affected by the plasma annealing. The lifetime is estimated from the photoconductivity, resulting in about 10−5 sec for hydrogenated polycrystalline silicon.