The photoconductivity $σ_p$ and its dependence on incident light intensity and temperature have been investigated in a series of amorphous silicon specimens at a photon energy of 2eV. Specimens were prepared by the DC glow discharge decomposition of silane. Doping was achieved by the pre-mixing of controlled amounts of phosphine before deposition.
The undoped specimens produced at the substrate temperature $T_s$~300℃ are much more photoconductive than those at $T_s$＜200℃.
For the specimen prepared at $T_s$~300℃, the photocurrent is carried by the electrons in the extended states and the phonon assisted hopping at $E_A$ is not observed. The recombination mechanism which is monomolecular above 290K at lower illumination levels is changed to the bimolecular below 220K.
Inspite of P-doping the recombination mechanism is not changed. But the photoconductivity is increased. So it seems that the donor band states act not as recombination centers but as shallow trap centers.
