A CCD imager overlaid with a thin-film photodetector of a heterojunction ZnSe-Zn 1-x Cd x Te

A CCD imager which is composed of an interline transfer type scanner in the imaging area and a thin-film photodetector of a heterojunctjon ZnSe-Zn 1-x Cd x Te has been developed. The array consists of 506^{V} \times 404^{H} picture elements. The imaging area is about 6.7^{V} \times 9.0^{H} mm 2 in size which corresponds to that of a 2/3-in vidicon. For the device to achieve high performance, necessary conditions between the parameters of the overlaid thin-film photoconductor and the scanner have been analyzed. Blooming phenomenon is deeply related to the sensitivity. The blooming has been suppressed without sacrificing the sensitivity by applying the pulse operation of the heterojunction. As a result, excellent performances such as high sensitivity and large blooming suppression have been realized. The scene illumination if F 1.4 100 1x (S/N ratio is 46 dB for luminance signal) in a single-chip color camera. The blooming control capability is 250 times of the saturation exposure.