Cristian Alexandru Tivarus

Low-Crosstalk and Low-Dark-Current CMOS Image-Sensor Technology Using a Hole-Based Detector

As the pixel size of CMOS image sensors (CIS) shrink, problems associated with crosstalk become more severe for devices built using mainstream CMOS processing. This high crosstalk increases the amount of noise added to the final image (via an increase of the off-diagonal terms in the color correction matrix (CCM)) and degrades the modulation transfer function (MTF). Reducing dark current has also been challenging for such CIS imagers. At present, the solution to these problems has been to switch to n-type substrates since they have been used for interline charge-coupled devices (CCDs) for decades.

Bright-Pixel Defects in Irradiated CCD Image Sensors

We have examined environmental radiation sources for digital cameras to find the origins of bright-pixel defects known to accumulate with time. We show that beta and gamma emissions from camera parts and lenses cause image transients, but permanent damage can occur with alpha particles from the CCD cover glass. Our experiments with 14-MeV- and thermal-neutron beams confirm that cosmic rays are the primary cause of new imager bright points.