The impact of active base on the bulk current in silicon heavily irradiated detectors

The results of this study throw a new light on the impact of the active base with a low electric field on the bulk current in Si detectors exploited in the experiments at High-Luminosity Large Hadron Collider (HL-LHC) at CERN at fluences beyond 1 x 10(15) n(eq)/cm(2). The profiles of the electric field, E (x), and the bulk current densities in Si p(+) -n-n(+) detectorswere simulated for fluences up to 5 x 10(16) cm(2). The E (x) profiles showed a double-peak shape and active base in between which acts as electrically neutral conductive base or electrically neutral depleted region changing its type versus the bias voltage and irradiation fluence. A comparison between the simulated and experimental data at fluences up to similar to 10(17) n(eq)/cm(2) showed the dependence of current on fluence to be converted from linear to the square-root. The conversion explains the saturation of current in silicon detectors irradiated to very high fluences, which is advantageous in their application in HL-LHC.