Comparing Spreading Resistance Profiling and C-V characterisation to identify defects in silicon sensors

Abstract

The quality and functionality of a silicon sensor strongly depends on the effective doping concentration of the active silicon bulk. The creation of additional defects, by certain steps in the production or through irradiation in a particle beam, can heavily influence its performance.Several methods exist to characterise the bulk material for a siliconsensor. C-V characterisation is a widely implemented, non-destructivemethod to extract the depth profile of Neff. A technique which israrely used at laboratories developing silicon sensors is SpreadingResistance Profiling (SRP) which directly measures the resistivity ofthe silicon. We will show, that a comparison of measurements fromthese two methods can yield important information on the defectconcentration in the bulk of the silicon. To demonstrate thetechnique, we investigated a sensor material where the active regionwas reduced using a deep diffusion process which is assumed to createadditional defects in the bulk.