Measurement of spatial distributions of mobility and conductivity in electron-beam-irradiated PMMA

Spatial distributions of electric field intensity, mobility, and electric conductivity in PMMA can be obtained by combining the volume charge distribution measured using the pulsed electroacoustic method, the current continuity equation, and Poisson´s equation. The exact measurement of charge distribution and its decay with respect to time allows the measurement of spatial distribution of mobility and conductivity due to the remaining charge after e-beam irradiation. For electron beam energies of 0.5, 0.75, 1.00 and 1.25 MeV on the PMMA sample, distributions of charge density, electric field intensity, mobility and conductivity depended on the electron beam energy. For sample temperatures of 27, 40, 60 and 80°C, these distributions were also obtained. Charge mobility in the sample became uniform as the sample temperature increased. At high temperature, volume charges were thermally excited and moved easily. Therefore, the mobility and conductivity increased with increasing sample temperature