SATICON: A new photoconductive camera tube with Se-As-Te target

In order to decrease lag and after-images in blocking-contact photoconductive camera tubes, sufficient electron mobility is required as well as hole mobility, even if a p-type photoconductor is used. In this connection, a new photoconductive target of selenium doped with arsenic and tellurium has been developed. Arsenic doping is used to prevent selenium crystallization. Tellurium doping is used near the signal electrode to increase red sensitivity. Along with the hole blocking contact at the signal electrode, a blocking structure is formed on the beam-scanned surface of the target to prevent injection of the beam electrons. The SATICON tube, employing this target, demonstrates the following characteristics. The sensitivity is 300-450 µA/1m, the gamma is nearly unity, and the spectral response covers the entire visible region. A 2/3-in tube shows a modulation transfer curve as high as 30 percent at 400 TV lines, Its lag is 3 percent at a signal current of 200 nA. Applications to TV broadcasting are expected.