Heat enhancement of radiation resistivity of evaporated CsI, KI and KBr photocathodes

The photoemissive stability of as-deposited and heat-treated CsI, KI and KB r evaporated thin films under UV radiation is examined in this paper. After the deposition, some photocathodes were annealed for several hours at 90 d egrees C in vacuum and their performance was then compared to the performan ce of non-heated samples. We observed that the post-evaporation thermal tre atment not only increases the photoyield of CsI and KI photocathodes in the spectral range of 115-190 nm, but also reduces CsI, KI and KBr photocurren t degradation that occurs after UV irradiation. KBr evaporated layers appea red to be more radiation-resistant than CsI and KI layers. Post-deposition heat treatment did not result in any significant Variation of KBr UV sensit ivity. (C) 2000 Elsevier Science B.V. All rights reserved.