Modeling dark signal of CMOS image sensors irradiated by reactor neutron using Monte Carlo method

Abstract

The dark signal degradation of the CMOS image sensor (CIS) was induced by neutron radiation, and it was modeled by Geant4, which is a three-dimensional Monte Carlo code. The simplified model of the CIS array was established according to the actual pixel geometry, material, and doping concentration. Nuclear elastic interaction and capture interaction were included in the physical processes, and the displacement damage dose in the space charge region of the pixel was calculated. The mean dark signal and dark signal distribution were modeled using Geant4, and the physical mechanisms were analyzed. The modeling results were in good agreement with the experimental and theoretical results.

Comparison of the dark signal degradation induced by Gamma ray, proton, and neutron radiation in pinned photodiode CMOS image sensors

“…Therefore, the dark signal spike tails are larger than those induced by neutrons at the same radiation fluence. The experimental results shown in Figure 1(b) are consistent with the simulation results in the literatures [6,9].…”

“…Although many studies investigated the radiation effects in CISs [1][2][3][4][5][6][7][8][9], few studies focused on the comparison of the dark signal degradations in PPD (pinned photodiode) CISs induced by cobalt-60 Gamma ray, proton, and neutron radiation.…”

Analysis of displacement damage effects on the charge-coupled device induced by neutrons at Back-n in the China Spallation Neutron Source

“…As has been described in our previous research work on the effects of neutron irradiation on the ∆DSNU of CMOS image sensors, ∆DSNU 2 is linear with neutron irradiation fluence. [10] The mechanism of the irradiation-induced increase in DSNU of the CCD is similar to that of a CMOS image sensor. Therefore, DSNU 2 is linear with neutron irradiation fluence, and the goodness-of-linear fit R 2 is better than 0.989.…”

“…Reactor neutrons are often used to analyze displacement damage effects. [10] However, there are also some inconveniences when irradiation experiments are carried out at a neutron reactor. For example, it is difficult to change the beam spot, it takes several days for the neutron activation ef-fects to die down before the irradiated devices can be measured and online radiation effects measurement is complex.…”