Simulation of the high frequency C–V characteristics of lateral PN junctions on polysilicon films

In this paper, a monodimensional simulation program of the high frequency capacitance characteristics of reverse biased lateral polysilicon PN junctions is presented. It is based on the resolution of Poissonʹs equation in order to determine the charge variation in the structure induced by the application of an external potential. The geometrical model assumes that the polysilicon layer is composed by a succession of defined mean grain size crystallites, separated by lateral grain boundaries which are parallel to the metallurgic junction. To validate the program, many P+N junction structures with different layer thicknesses have been simulated. Experimental and simulated C–V curves are fitted to obtain the grain boundaries traps density. Results show clearly that the electronic properties of the polycrystalline deposited films improve during the layer growth.