Abstract :
As an ideal resistive sea for the silicon diode array camera tube target, GaAs films about 1000 Å thick have been investigated. The films were fabricated on the targets by a single-source evaporation technique. The tubes were vacuum processed as an elevated bake temperature of 400°C, which assures much longer cathode life. The tube performance has been measured to be much superior to the diode array target using an Sb2S3film and compatible to tubes using conducting top hats. In general, good beam acceptance results in considerable improvements in signal-handling capability, lag, resolution, and aging characteristics. Fortunately, good beam landing, even at low target voltages, is characteristic of the GaAs film; this results partly from the poor secondary emission ratio of GaAs films. The excellent tube performance achieved, in addition to the good beam landing, originates in the inherent nature of GaAs, which allows high leakage through the film even though the film sheet resistivity is high. Preliminary tests have shown two orders of magnitude better aging results than those of Sb2S3films three times thicker.
