Preliminary evaluation of Gaussian-doped monolithic active pixel sensors for minimum ionizing particles detection

The monolithic active pixel sensors (MAPS) using a standard dual-well CMOS process on lightly doped epitaxial wafers have demonstrated competitive tracking and imaging performance for minimum ionizing particles (MIP) detection. In this paper, a Gaussian-doped substrate is proposed to improve the performance of charge collection. Preliminary theoretical analysis and physical level simulations are presented. The results illustrate that the internal distributions of electric potential and electric field are improved and about 70% more charged-particle generated electrons can be collected in 50 ns (about one half with respect to the case of standard epitaxial layer) because the diffusion towards neighbor pixels is significantly reduced. Furthermore the manufacturability of such wafer is discussed.