Effect of surface recombination and injection level on the diffusion length obtained by simulation of the SPV method

Abstract

The procedure of measuring diffusion length by the surface photovoltage (SPV) method is modeled with a specially designed numerical simulation program. The effect of surface recombination and injection level on the obtained diffusion length is investigated using the simulation. The results show that at low injection levels the surface recombination does not influence the diffusion length, but at high injection levels the diffusion length is dependent on surface recombination velocity. It is shown that at high injection levels the effect of different surface recombination velocities on the diffusion length is different. For low surface recombination velocities raising the injection level tends to reduce the diffusion length, whereas for high surface recombination velocities it tends to raise the diffusion length. These simulation results are interpreted and discussed in detail.