Proceedings of SPIE
Charge coupled devices, Image processing -- Digital techniques, Imaging systems -- Image quality
The depletion edge in Charge-Coupled Devices (CCD) pixels is dependent upon the amount of signal charge located within the depletion region. A model is presented that describes the movement of the depletion edge with increasing signal charge. This dynamic depletion edge is shown to have an effect on the amount of dark current produced by some pixels. Modeling the dark current behavior of pixels both with and without impurities over an entire imager demonstrates that this moving depletion edge has a significant effect on a subset of the pixels. Dark current collected by these pixels is shown to behave nonlinearly with respect to exposure time and additionally the dark current is affected by the presence of illumination. The model successfully predicts unexplained aspects of dark current behavior previously observed in some CCD sensors.
"Dynamic CCD pixel depletion edge model and the effects on dark current production," Justin C. Dunlap, M. M. Blouke, Erik Bodegom, Ralf Widenhorn, Proc. SPIE. 8298, 82980F (2012).