A high-sensitivity solid-state image sensor using a thin-film ZnSe-Zn1-xCdxTe heterojunction photosensor

A high-sensitivity solid-state image sensor in which a charge-transfer device is overlaid by a thin-film photoconductor for the photosensor has been developed. The scanning registers are composed of interline transfer-type bucket-brigade registers (BBD) in the imaging area and charge-coupled registers (CCD) in the horizontal scanning circuit. The special feature of this device is that the thin-film photoconductor of ZnSe-Zn1-xCdxTe heterojunction is directly formed not only on the Si-diode area but also on the scanning circuit area of BBD to obtain a high-aperture ratio. This solid-state image sensor has 506^V× 413^Hpicture elements and the imaging area is about 10.4^V× 13.5^Hmm which corresponds to that of a 1-in vidicon. High sensitivity of 0.46 µA/lx (2856 K) and large blooming control capability have been obtained by this structure. The characteristics such as sensitivity, dark current, resolution, and blooming peculiar to the structure of a solid-state imager overlaid by a photoconductor are also discussed.