Lateral polysilicon p(+)-p-n(+) and p(+)-n-n-(+) diodes are fabricated and their electrical characteristics, such as ON-resistance, ideality factor and reverse current, are studied as a function of the polysilicon microstructure, the type and amount of doping in the lightly doped region and the length of the lightly doped region. Increasing the polysilicon grain size reduces the ON-resistance. The ON-resistance decreases while the reverse current increases with an increase in the amount of doping in their lightly doped region. The ON-resistance is higher and the reverse current is lower in diodes having p-type lightly doped regions. With an increase in the length of the lightly doped regions, the ON-resistance increases, while the reverse current does not change. The ideality factor does not depend upon the length of the lightly doped region, type of doping in this region and the grain size of polysilicon. The experimental observations are explained using a combination of field enhanced emission and a formulation that considers the effect of the grain-boundary segregation of dopants. (C) 2002 Elsevier Science Ltd. All rights reserved.