Three Color Detection in the Charge Integration Regime by ATCD for Large Area Applications

Abstract

AbstractLarge area color image scanners are currently being widely investigated. The a-Si:H/a-SiC:H Adjustable Threshold Color Detector (ATCD) recently presented by the authors is suitable for greatly simplifying the structure of the arrays since ATCDs have just two external electrical connections. This makes possible to use the row-column addressing of pixels.In this work, the transient operation of ATCDs in the charge integration regime is discussed. Charge integration is operated by photocurrent discharging the three series connected capacitances which compose the device structure. The penetration depth of the incident radiation depends on the wavelength and determines which of the three capacitances is discharged. The applied bias voltage determines the polarization of the three junctions and the three capacitance actually sensed. Correct blue, green and red light detection is shown in the read-out transients and the read-out and saturation times are presented. Finally design rules of the device and read-out system are given in order to achieve a correct detection of the three colors.