Electronic transport in polycrystalline Pbl2 films

Electronic transport and optical measurements in polycrystalline Pbl(2) are reported as part of a study to evaluate the material for large area x-ray imaging applications. The films are deposited by vacuum evaporation with thickness 20-100 mu m and have grain sizes of up to 10 mu m. The room temperature hole drift mobility measured by time-of-flight is 2x10(-2)-1.5x10(-1) cm(2)/V s, depending on the specific sample, with an activation energy of 0.25 eV. Hole charge collection measurement gives about 10(-6) cm(2)/V for the mobility-lifetime product. Details of the electron transport were not determined in this study because the mobility is too small. The hole transport is discussed in terms of a trapping model with either a discrete level above the valence band or a disorder-induced band tail. Optical absorption, photoconductivity, and Hall effect measurements are also reported. (C) 1999 American Institute of Physics. [S0021-8979(99)07816-0].