The Transverse Field Detector: a CMOS active pixel sensor capable of on-line tuning of the spectral response

The Transverse Field Detector (TFD) is a CMOS photosensitive device for imaging applications that performs color detection without color filters. Suitably biased surface contacts generate in the Silicon active layer an electric field configuration that drives the carriers generated at different depths to different surface contacts. The TFD avoids the light losses caused by conventional Color Filter Arrays (CFA) on top of a sensor and does not need demosaicing to reconstruct the color at each position. With respect to color pixels based on the use of CFA, the TFD offers the possibility of spectral responses tuning, through a suitable change of the surface electrodes biasing. With respect to color pixels based on the use of stacked junctions the TFD offers the possibility of four-color response. In this work experimental results obtained with first prototypes are discussed showing the color tuning capability. The design, and realization of a first mini matrix of Active Pixel TFD in a 90 nm standard process is presented.