J. Phys. Colloques
Volume 42, Numéro C4, Octobre 1981Proceedings of the Ninth International Conference on Amorphous and Liquid Semiconductors
|Page(s)||C4-527 - C4-530|
J. Phys. Colloques 42 (1981) C4-527-C4-530
PHOTOVOLTAIC EFFECT IN INTERSTITIALLY DOPED a-Si:HS. Kumar and S.C. Agarwal
Department of Physics, Indian Institute of Technology, Kanpur 208016, India
a-Si:H films prepared by d.c. glow discharge of silane are doped with lithium by thermal diffusion at 450K. The dark conductivity at room temperature is found to increase by 4 orders of magnitude upon doping, whereas the conductivity activation energy (ƊE) decreases from 0.62eV to 0.17eV. The thermopower(S) for the doped films is found to be negative and a plot of S vs 1/T has a slope (ES) of about 0.17eV. The photoconductivity (σph) for the doped films is found to increase by a factor of 5. In some samples, having a coplanar geometry of electrodes, an electric field ≈ 103V/cm is applied between the electrodes immediately after Li evaporation at 450K and the samples are allowed to cool down to room temperature in the presence of the electric field. This results in a gradient of Li ions along the length of the sample, as evidenced by a photovoltage which appears upon shining white light onto these samples. In contrast, no photovoltage is observed in samples, which are not subjected to the electric field.