The energy profile of the density of states over the mobility gap was determined jointly by the defect pool model calculation and the Fourier transform of the transient photoconductivity, for intrinsic and P-doped a-Si:H. From the Fourier transform of the transient photoconductivity, an increase of the density of states around the donor energy level, at about 0.16eV below the conduction mobility edge, and a decrease of the tail width below this level from 0.021 to 0.015eV were measured as a doping effect. This disorder effect on the conduction band tail caused by the P dopant was consistent with the induced doping changes in the dangling bond defect distribution calculated by the defect pool model. Transient photoconductivity decays were then generated by numerical simulation using this density of states distribution and compared to experimental transient photoconductivity data. All observed features in the transient photo-response were reproduced by the simulation, namely the short time rapid decrease followed by the long power law decay in the intrinsic a-Si:H, and the long non-dispersive flat region in the P-doped a-Si:H.

Defect Pool Model Based Transient Photoconductivity and the Conduction Band Tail Profile in a-Si:H. A.Merazga, A.F.Meftah, A.M.Meftah, C.Main, S.Reynolds: Journal of Physics - Condensed Matter, 2001, 13[48], 10969-77