Final stage of the charge-transfer process in charge-coupled devices

The final stages of transfer of charge from under a storage gate is formulated analytically including both fringing-field induced drift and diffusion. Analytic solutions to these equations are presented for constant fringing fields, and a system of equations for spatially varying fields is developed. Approximate solutions for spatially varying fringing fields, when combined with a lumped-parameter model of the self-induced field effects, are shown to give a reasonably accurate representation of the free-charge transfer process.