An experimental crystalline-selenium vidicon

The use of polycrystalline Se as the photosensitive target of a vidicon image tube has been demonstrated for the first time. The mode of operation of this target layer is fundamentally different from that of the amorphous-Se vidicon target, which is commonly described as a photosensitive insulator layer. In contrast, the explanation for the crystalline-Se vidicon operation, as proposed here, is based on the utilization of a reverse-biased heterojunction contact between n-type SNO2and p-type crystalline Se. A fabrication process has been developed which yields target layers with an attractive combination of operating characteristics. This new type of vidicon has the following nominal operating parameters: dark current ≃ 5-10 nA, peak sensitivity ≃ 0.270 A/W, peak quantum efficiency ≃ 60 percent, and 50-ms lag ≃ 10 percent. Compared to the standard Sb2S3vidicon, this experimental crystalline-Se vidicon has more than twice the sensitivity and less than half as much lag and dark current.