Influence of Exposure to CO, CO₂ and H₂O on the Stability of GaAs Photocathodes

Abstract

The influence of CO, CO 2 and H 2 O gases on the stability of negative-electron-affinity (NEA) GaAs photocathodes during operation is investigated in the present work. We have found that exposure both to H 2 O and CO 2 decreases the photocurrent of the photocathode. However, exposure to CO, which is known as a harmful gas to various photocathodes, has little effect on the photocathode stability. Furthermore, the effects of these gases on the restoration of the photocurrent by additional cesium deposition are investigated. These results are discussed with regard to the Cs/O activation layer which plays an important role in NEA GaAs photocathodes.