A GaAs-Cs-O transmission photocathode

Abstract

Polycrystalline GaAs layers have been deposited on sapphire substrates by the AsCl3-Ga-H2 vapour transport method, and treated with caesium and oxygen. A layer 0·6 μm thick when operated as a photocathode has shown a luminous sensitivity of 70 μA lm−1, in transmission. Thicker layers have shown lower sensitivities. Spectral response curves are given for layers 0·6 and 0·8 μm thick and show yields out to 1·4 ev.