Electronic transport in polycrystalline Pbl2 films

Electronic transport and optical measurements in polycrystalline ${\mathrm{Pbl}}_{\mathrm{2}}$ 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 μm and have grain sizes of up to 10 μm. The room temperature hole drift mobility measured by time-of-flight is ${\text{2×10}}^{\text{−2}}{\text{–1.5×10}}^{\text{−1}} {\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s},$ depending on the specific sample, with an activation energy of 0.25 eV. Hole charge collection measurement gives about ${10}^{\text{−6}} {\mathrm{cm}}^{\mathrm{2}}\mathrm{/V}$ 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.