Study of lateral polysilicon PN diodes C-V characteristics: Modeling and experiments

In this work, we propose a monodimensional numerical modeling of lateral polysilicon PN diode C-V characteristics by taking into account the localization of the traps at the grain boundaries. The C-V characteristic simulation shows that for high doping concentration, the curve behavior is similar to the case of monocrystalline junction. However, for low doping concentration, these characteristics present a succession of down stairs shape. This is due to the intergranular trap states pinning of the Fermi level and consequently, to the electrostatic potential shielding at the grain boundaries. In the simulation, we consider the following parameters: doping concentration, intergranular traps states density and their energetic position, number of the grain boundaries and crystallite size. The obtained results show that the electrostatic potential shielding is stronger for large crystallites, for high intergranular trap densities and for deepest traps. The simulated C-V characteristics have been fitted to the experimental measurements. For a doping concentration equal to 6 x 10(16) and 7 x 10(17) cm(-3), the corresponding values of the trap density are 10(12) and 2 x 10(12) cm(-2), respectively. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.